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Reciprocating Compressors for industrial refrigerationGrasso 12

Product Informationpador9020gbr_3

COPYRIGHT

All Rights reserved. No part of this publication maybe copied or published by means of printing, photo-copying, microfilm or otherwise without prior writtenconsent of Grasso.This restriction also applies to the correspondingdrawings and diagrams.

LEGAL NOTICEThis publication has been written in good faith. How-ever, Grasso cannot be held responsible, neither forany errors occurring in this publication nor for theirconsequences.

Product Information | Grasso 12Reciprocating Compressors for industrial refrigeration

2 GEA Refrigeration Netherlands N.V. | pador9020gbr_3 | Generated 27.09.2013

PREFACE

General

1. All documentation can be downloaded via ourweb site.

2. Grasso’s technical manuals includes “genericparagraphs”; this means that it can occur thatnot all data as described is relevant for the cur-rent compressor series as mentioned in thismanual. (For instance, not all compressor seriesare suitable for all mentioned refrigerants or notall compressor series includes two-stage com-pressors)

Directives

Equipment is based on Pressure Equipment Direc-tive (PED 97/23/EG) regulations and according toMachine Directive (MD 2006/42/EG) regulations.

The applied standards are:NEN-EN-IEC 60204, NEN-EN-ISO 12100, NEN-EN-ISO 13857, NEN-EN 378


GEA Refrigeration Netherlands N.V. | pador9020gbr_3 | Generated 27.09.2013 3

TABLE OF CONTENTS1 DESCRIPTION AND SELECTION OF COMPRESSOR 7

1.1 INTRODUCTION AND SCOPE 71.1.1 OUTLINE 71.1.2 TYPE DESIGNATION 71.1.3 APPLICATION 71.1.4 DRIVE SYSTEM 71.1.5 SELECTION COMPRESSOR AND ACCESSORIES 71.1.6 PRESSURE TESTS 71.1.7 ACCEPTANCE TEST 71.1.8 STANDARD SCOPE OF SUPPLY 71.1.9 OPTIONS 71.1.10 HEAVY DUTY THRUST BEARING 8

1.2 GENERAL DATA 81.2.1 TECHNICAL DATA 81.2.2 MAIN DIMENSIONS AND SPACE REQUIREMENTS 121.2.3 SHAFT END COMPRESSOR 161.2.4 SOUND RATING GENERAL 16

1.2.4.1 SOUND DATA 12 171.2.5 STARTING TORQUE 17

1.2.5.1 COMPRESSOR AND TORQUE COMPONENTS 191.2.6 FREE FORCES AND MOMENTS 21

1.2.6.1 SURVEY 211.3 LIMITS OF OPERATION AND FIELDS OF APPLICATION 23

1.3.1 GENERAL LIMITS AND FIELDS OF OPERATION GRASSO 12 231.3.2 PRECISE FIELD OF APPLICATION 271.3.3 FIELDS OF APPLICATION SINGLE-STAGE AND BOOSTER 27

1.3.3.1 FIELDS OF APPLICATION 281.3.4 FIELDS OF APPLICATION TWO STAGE 29

1.3.4.1 FIELDS OF APPLICATION DIAGRAMS 301.3.5 LIMITATIONS OF PART-LOAD OPERATION 311.3.6 STARTING UP OF TWO-STAGE COMPRESSORS 31

1.4 LUBRICATING OILS (choice and recommendations) 331.4.1 OIL SELECTION TABLE 33

1.4.1.1 REMARKS 331.4.2 STRONGLY RECOMMENDED OIL TYPES 341.4.3 ACCEPTED NH3 AND HCFC OIL TYPES 351.4.4 ACCEPTED HFC OIL TYPES 36

1.5 DESIGN DETAILS OF COMPRESSOR 371.5.1 COMPRESSOR HOUSING 37

1.5.1.1 DIAGRAMS 381.5.2 CYLINDERS AND MOVING PARTS 391.5.3 ROTARY SHAFT SEAL 39

1.5.3.1 ROTARY SHAFT SEAL 401.5.4 SUCTION AND DISCHARGE VALVES 40

1.5.4.1 DIAGRAM SUCTION AND DISCHARGE VALVES 411.5.5 VALVE-LIFTING MECHANISM 411.5.6 PRINCIPAL CONNECTIONS, GAS SUCTION FILTER AND PRESSURE EQUALISING

421.5.7 RELIEF VALVES 421.5.8 HEAVY DUTY THRUST BEARING CONSTRUCTION 42

1.5.8.1 EXPLODED VIEW HEAVY DUTY THRUST BEARING 431.5.9 OIL PUMP AND FILTERS 43

1.5.9.1 OIL PUMP AND THRUST BEARING 441.5.10 CONTROL AND LUBRICATION OIL SYSTEM (Figure 18, page 44 and Figure 20,

page 45) 452 DESCRIPTION AND SELECTION OF ACCESSORIES 46

2.1 CAPACITY CONTROL SYSTEMS 462.1.1 CAPACITY CONTROL SELECTION 462.1.2 PART-LOAD POWER CONSUMPTION AND ALLOWED PART LOAD STEPS COMSEL

46



2.1.3 SURVEY CAPACITY CONTROL SYSTEMS AND UNLOADED START 462.1.3.1 START AND STOPPING PROCEDURE SINGLE FIXED SPEED COMPRES-

SORS 462.1.3.2 GUIDE LINE FREQUENCY CONTROL 46

2.1.4 WIRING LOGIC NORMALLY OPEN UNLOADED START SOLENOID 472.1.5 ELECTRIC CAPACITY CONTROL AND FAST PULL DOWN (FPD) 48

2.1.5.1 GENERAL DIAGRAM OF ELECTRICALLY OPERATED CAPACITY CON-TROL 48

2.1.5.2 DIAGRAMS 492.1.6 MANUAL CAPACITY CONTROL 55

2.2 CONTROLS, SAFETIES, GAUGES AND SWITCHES 592.2.1 CONTROLS SINGLE STAGE 592.2.2 CONTROLS TWO STAGE 602.2.3 “GSC OP” AND “GSC TP” CONTROL DEVICE 612.2.4 MECHANICAL SAFETY SWITCHES IN ADDITION TO MICRO-PROCESSOR-BASED

CONTROL SYSTEMS 622.2.5 PRESSURE SAFETY SWITCH PANEL 63

2.2.5.1 ELECTRICAL WIRING SCHEMATIC RT260A 642.2.6 PRESSURE GAUGES 662.2.7 THERMO-MASTER 672.2.8 CYLINDER HEAD WATER COOLING SYSTEM 68

2.3 DIRECT AND V-BELT DRIVE 702.3.1 SELECTION OF DIRECT DRIVE 70

2.3.1.1 DIRECT DRIVE OPTIONS 702.3.1.2 COUPLING DIMENSIONS 70

2.3.2 SELECTION OF V-BELT DRIVE 702.3.2.1 DETAILS V-BELT DRIVE 70

2.4 PACKAGED BASE FRAME AND FOUNDATION BLOCK 732.4.1 PACKAGED BASE FRAME 73

2.4.1.1 PACKAGED BASE FRAME 732.5 OIL SEPARATOR; OIL RETURN PROTECTION; OIL LEVEL FLOAT SWITCH; OIL EQUALISING

AND OIL RETURN 742.5.1 (COMMON) OIL RETURN SYSTEMS 74

2.5.1.1 EXPLANATION OIL RETURN SCHEMATICS (Section 2.5.1.2, page 74and Section 2.5.1.3, page 75) 74

2.5.1.2 SCHEMATIC OIL RETURN SYSTEM I 742.5.1.3 SCHEMATIC OIL RETURN SYSTEM II 75

2.5.2 OIL SEPARATORS SERIES OS (25 BAR) 772.5.3 OIL RETURN PROTECTION 802.5.4 CRANKCASE OIL LEVEL SWITCH 81

2.5.4.1 CRANKCASE OIL LEVEL FLOAT SWITCH 822.5.5 OIL RESERVOIR FOR MARINE USE 82

2.5.5.1 OIL RESERVOIR FOR MARINE USE 822.5.5.2 Heating element for oil reservoir 83

2.6 OIL COOLER 832.6.1 OIL COOLER SELECTION GRASSO 12E 85

2.7 CRANKCASE HEATER 852.7.1 HEATER FITTING DETAIL 86

2.8 STOP VALVES, FLANGES AND FILTERS 882.8.1 STOP VALVES, CHECK VALVES AND FLANGES SUCTION AND DISCHARGE CON-

NECTIONS 882.8.2 STOP VALVE FITTING DETAILS 882.8.3 INTERMEDIATE SUCTION GAS FILTER 90

2.9 SPECIAL TOOLS 902.10 HAND-OPERATED OIL PUMP 902.11 INTERSTAGE COOLING SYSTEMS 91

2.11.1 SURVEY OF INTERSTAGE COOLING SYSTEMS FOR TWO-STAGE COMPRESSION91

2.11.1.1 Graphics interstage cooling system A and B 952.11.2 INTERSTAGE COOLER (A and B) 99

2.11.2.1 MAIN DIMENSIONS AND SPACE REQUIREMENTS INTERSTAGE SYS-TEMS A AND B, GRASSO 12 101

2.11.3 OPEN (SYSTEM C ) AND CLOSED (SYSTEM D) FLASH INTERSTAGE COOLING 102



1 DESCRIPTION AND SELECTION OF COMPRESSOR

1.1 INTRODUCTION AND SCOPE

1.1.1 OUTLINE

Grasso 12(E) is the designation of a series of open,single- acting, reciprocating refrigeration compres-sors with trunk-type pistons and with 2 up to 12 cylin-ders in V- and W-arrangement.The series consist of 15 types, 6 single-stage and 9integral two-stage (compound) compressors. Thesingle-stage types can also be used as booster com-pressors.

1.1.2 TYPE DESIGNATION

The following examples will explain the type designa-tion:

6 cylinder single-stage compressor typeGrasso 612:

6, Number of cylinders

12 , Series indication

9 cylinder two-stage compressor typeGrasso 6312

6, Number of LP cylinders

3, Number of HP cylinders

12, Series indication

1.1.3 APPLICATION

• Industrial operation.

• Evaporating temp. between -68 and +22 °C.

• Refrigerants: amongst others NH3, R134a, R22,R404A, R507.

• For special applications (cascade systems,chemical processes, etc.) consult Grasso.

1.1.4 DRIVE SYSTEM

• Electric motor: direct or V-belt.

• Max. speed 1000 min-1

• Rotation normally counter-clockwise when facingshaft end of compressor.

1.1.5 SELECTION COMPRESSORAND ACCESSORIES

Consult Grasso"s software program COMSEL(COMpressor SELection) which can be downloadedfrom Grasso’s internet site.

1.1.6 PRESSURE TESTS

• Test pressure 34.5 bar(e).

• Design pressure 24.0 bar(a).

• Test run with air.

1.1.7 ACCEPTANCE TEST

• Acceptance test under design conditions, acc. toISO 917, witnessed by the customer possible onrequest.

1.1.8 STANDARD SCOPE OF SUP-PLY

• Standard bare compressor:

® painting pigeon blue

® oil and suction filters

® Filled with nitrogen

® Mating flanges suction and discharge con-nections

® Purge valve(s) on discharge line(s)

Supplied loose:

• Suction filter element, including seals (running-infilter is factory mounted)

• Oil discharge filter for first oil change, includingseals (running-in filter is factory mounted)

• Swivel coupling for oil return connection

• Installation and Maintenance Manual.(IMM)

Not included:

• oil charge.

1.1.9 OPTIONS

• Lloyds approval (other approvals on request),

• Accessories as mentioned in next chapter.

• Heavy duty oil discharge filter.

• Back pressure independent relief valves, 23.0bar acc. to DIN 8975. One or two relief valvesare required depending on type of compressor.



• Oil differential pressure indicator on oil dischargefilter.

fig.1: Option; Oil differential pressure indicator on oil dis-charge filter

On request:

• Non standard paint colour

• Extra purge and evacuating stop valve(s) on suc-tion line(s)

• Thermometers in suction and discharge lines

• Explosion proof acc. to EEX-dIIC-T5

• Check valves in discharge lines

• Clockwise direction of rotation

1.1.10 HEAVY DUTY THRUST BEAR-ING

The compressor can be fitted with 2 types of thrustbearings:

A. Rotational steel disc in combination with a sta-tionary white metal/steel backed ring (Standard)

B. "Heavy duty" roller thrust bearing(HD)

The design "A" is the standard execution for generaluse. The "HD" roller thrust bearing design, however,becomes compulsory for compressors running in

NH3 installations with high (design) suction pres-sures or where frequent high suction pressurestarts, irrespective of design suction pressures, areexpected. Besides the above mentioned criteriacompressors used for bottling lines and tube iceinstallations must be fitted with the HD roller bearingdesign.

Selection

I. To (suction) :

> -5.0 oC

II. Applications :

II.1 Bottling lines

II.2 Tube ice installations

III. Control :Frequent high (suction) pressure start-ups

Warning!

If the running conditions are stated tothe manufacturer the right type ofthrust bearing will automatically beselected. Lack of this information canresult in fitting the wrong thrust bear-ing and could result in damage to thecompressor

1.2 GENERAL DATA

1.2.1 TECHNICAL DATA



Tech

nica

l Dat

a of

Gra

sso

12 s

erie

s

CO

MPR

ESSO

R T

YPE

Sing

le-s

tage

Two-

stag

e

212

312

412

612

912

1212

2112

3112

4212

5112

6312

7212

8412

9312

1021

2

Num

ber o

f cyl

inde

rsz L

23

46

912

23

45

67

89

10

z H1

12

13

24

32

Cyl

inde

r arr

ange

men

t

1xV

1xW

2xV

2xW

3xW

4xW

1xW

2xV

2xW

2xW

3xW

3xW

4xW

4xW

4xW

Cyl

inde

r bor

eD

m m16

0

Pis

ton

stro

keS

m m11

0

LP S

wep

t vol

-um

e at

full-

load

and:

n=10

00/

min

-1V

sm

3 /h26

539

853

179

611

9415

9226

539

853

166

479

692

910

6211

9413

27

Rat

io L

P/H

P s

wep

t vol

-um

e (Z

L/Z H

) at f

ull l

oad

ϕ

23

25

23.

52

35

Sta

ndar

d di

rect

ion

ofro

tatio

n

coun

ter-

cloc

kwis

e w

hen

faci

ng s

haft

end

Sta

ndar

dco

mpr

es- s

orsp

eeds

(with

V-

belt

driv

e) a

tm

otor

spe

ed:

1450

min

-1

(50

Hz)

nm

in-1

535-

600

- 675

- 720

- 765

- 860

- 965

1750

min

-1

(60

Hz)

520-

550

- 580

- 650

- 725

- 820

-8 7

0- 9

20

Sta

ndar

d st

eps

of c

apac

ityco

ntro

l(e

xpre

ssed

in

S

1%

100-

5010

0-67

- 33

100-

75- 5

0

100-

83- 6

7-50

- 33

100

-89

67-

44- 3

3

100-

83- 6

7-50

- 25

1 Single stage



Tech

nica

l Dat

a of

Gra

sso

12 s

erie

s

CO

MPR

ESSO

R T

YPE

Sing

le-s

tage

Two-

stag

e

212

312

412

612

912

1212

2112

3112

4212

5112

6312

7212

8412

9312

1021

2

% o

f ful

l-loa

dsw

ept v

olum

e):

B2

100-

5010

0-67

- 33

100-

75- 5

0

100-

83- 6

7-50

100-

67- 4

4

100-

75- 5

8-42

Sp

age

9

100-

5010

0-67

- 33

100-

75- 5

0

100-

83- 6

7-50

- 33

100-

89- 7

8-67

- 56-

44- 3

3

100-

92- 8

3-75

- 67-

58- 5

0-42

- 33-

25

Bp

age

10

100-

5010

0-67

-33

100-

75- 5

0

100-

83- 6

7-50

100-

67- 4

4

100-

75- 5

8-42

T310

010

0-67

100-

75- 5

0

100-

80- 6

0-40

100-

67- 3

3

100-

86- 7

2-57

- 43-

29

100-

75- 5

0-25

100-

78- 6

7-56

- 45-

33

100-

80- 7

0-60

- 50-

30

Mas

s of

bar

e co

mpr

es-

sor (

with

out f

lyw

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and

othe

r acc

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ries)

kg55

366

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9016

3066

088

511

0011

0014

4014

4017

0017

0017

00

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ppin

g m

ass

(app

rox.

)kg

623

730

880

1150

1505

1760

730

955

1200

1200

1555

1555

1830

1830

1830

Shi

ppin

g vo

lum

em

31.

751.

752.

22.

53.

54.

01.

752.

22.

52.

53.

53.

54.

04.

04.

0

Oil

char

ge in

cra

nkca

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d oi

l circ

uit (

cent

relin

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sig

ht g

lass

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37.

77.

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.67.

713

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.714

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.6

Mas

s m

omen

t of i

nerti

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cra

nk m

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nism

(with

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lyw

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kg .m 20.

2704

0.31

190.

3421

0.47

410.

6598

0.84

100.

3119

0.34

210.

4741

0.47

410.

6598

0.65

980.

8410

0.84

100.

8410

2 Booster3 Two stage



1.2.2 MAIN DIMENSIONS ANDSPACE REQUIREMENTS

fig.2



CO

MPR

ESSO

R T

YPE

212

312

412

612

912

1212

2112

3112

4212

5112

6312

7212

8412

9312

1021

2

Leng

thA

977

987

1307

1377

1792

2182

987

1307

1377

1377

1792

1792

2182

2182

2182

Wid

thB

1077

1171

1077

1171

1171

1171

1171

1110

1171

1171

1171

1171

1171

1171

1171

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C88

193

188

493

193

193

193

187

693

193

193

193

193

193

193

1

D

876

848

876

848

848

848

848

876

848

848

848

848

848

848

848

E

881

688

884

871

871

871

871

864

871

871

871

871

871

871

871

F

316

522

316

548

560

950

786

790

795

795

795

795

795

795

795

G

040

60

189

189

189

648

745

688

688

688

688

688

688

688

H

53

054

154

854

856

056

095

095

095

0

J

50

990

391

391

313

1513

1517

0517

0517

05

K

14

922

416

316

316

316

316

316

316

3

L

19

510

8.5

195

195

195

195

195

195

195

M

40

633

140

640

640

640

640

640

640

6

N

205

205

205

205

217

217

205

205

205

205

217

217

217

217

217

O

295

295

625

685

1075

2x73

2.5

295

625

685

685

1075

1075

2x73

2.5

2x73

2.5

2x73

2.5

P

345

345

345

345

369

369

345

345

345

345

369

369

369

369

369

MIN

IMU

M R

EQU

IRED

FR

EE S

PAC

E fo

r rem

oval

of:

flyw

heel

U70

070

070

070

070

070

070

070

070

070

070

070

070

070

070

0

cran

ksha

ftV

875

875

1205

1265

1655

2045

875

1205

1265

1265

1655

1655

2045

2045

2045

pist

on a

nd c

ylin

-de

r lin

erW

410

1011

6010

1011

6011

6011

6011

6010

1011

6011

6011

6011

6011

6011

6011

60

4 Minimum required free space for interstage cooling system A or B.



CO

MPR

ESSO

R T

YPE

212

312

412

612

912

1212

2112

3112

4212

5112

6312

7212

8412

9312

1021

2

X46

059

546

059

559

559

559

546

059

559

559

559

559

559

559

5

LOC

ATI

ON

OF

CEN

TRE

OF

GR

AVI

TY

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197

197

280

405

600

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197

280

405

405

600

600

795

795

795

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405

423

423

435

440

445

423

423

435

435

440

440

445

445

445

MA

IN C

ON

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NS

DN

(mm

)

(LP

) suc

tion

180

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012

512

512

565

6510

012

510

010

010

010

010

0

LP d

icha

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HP

suc

tion

2/3

50

5080

8080

8080

8080

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) dis

char

ge4

6565

8010

010

010

040

4065

6565

6565

6565

AU

XILI

AR

Y C

ON

NEC

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NS

suct

ion5

pres

-su

re5

1/4”

BS

P (p

lugg

ed o

ff)

LP d

isch

arge

pres

sure

page

14

6

HP

suc

tion

pres

-su

re7

dich

arge

pre

s-su

repa

ge 1

48

Cra

nkca

se p

res-

sure

9

lubr

icat

ing

oil

pres

sure

10

Oil

tem

pera

ture

11



CO

MPR

ESSO

R T

YPE

212

312

412

612

912

1212

2112

3112

4212

5112

6312

7212

8412

9312

1021

2

Oil

char

ge a

nddr

ain

valv

e12

1/2”

BS

P (p

lugg

ed o

ff; s

epar

ate

stop

val

ve, t

ype

TAH

8, s

uppl

ied

loos

e w

ith th

e co

mpr

esso

r)

Ret

urn

from

oil

sepa

rato

r or r

ec-

tifie

r13

1/2”

BS

P (p

lugg

ed o

ff; s

epar

ate

swiv

el c

oupl

ing,

sup

plie

d lo

ose

with

the

com

pres

sor)

Cra

nkca

sehe

ater

141/

2” B

SP

(plu

gged

off)

to s

uit t

hrea

d of

hea

ting

elem

ent

Oil

leak

age

drai

nof

rota

ry s

haft

seal

15cl

amp

coup

ling

prov

ided

with

ø12

x1.5

mm

ste

el p

reci

sion

tube

Con

trol o

il pr

es-

sure

16T-

coup

ling

5 When a microprocessor is applied (see also the relevant Data Sheet), these auxiliary connections are provided with a swivel couplingwith two connections. The straight-through and side connection of this swivel coupling are provided with a clamp coupling for ø6x1 mmsteel precision tube, in order to accomodate the temperature sensor element and the steel precision tube for the pressure transducerrespectivily.



1.2.3 SHAFT END COMPRESSOR

fig.3: Shaft end compressor

1.2.4 SOUND RATING GENERAL

General

The sound characteristics of the compressor seriesare stated in Lw.Lw is the average measured "sound power level" ofthe bare shaft compressor block without electricalmotor. These values are applicable for the followingconditions of operation:

• All cylinders in operation (full-load)

• All refrigerants

• All suction pressures

Sound power-frequency characteristics (Lw)

The sound level table shows the sound power level(Lw, expressed in dB, re 10-12 W) as a function ofthe octave band centre frequency for all compressortypes at different speeds. The data represent thesound power emitted by the compressor (body) onlyso excluding the influence of the electric motor andV-belt drive. Each dB-value is the direct or derivedresult of laboratory measurements according to ISO9614-1 (Measurement accuracy +/- 3 dB) and car-ried out by means of latest sound intensity analyzingsystem Model: Difa, type DSA 220C, software ver-sion D-TAC200 3.30 with a Microtech intensity probeSIS90 and Microtech microphones MK290.

Sound pressure level (Lp)

The sound pressure level, at a certain required dis-tance (> 3 mtr.) from the center of the package, canin theory be calculated with the formula:

Lp= Lw - 8 -20log R.

Refer to following paragraph.(R = distance from the centre of the package to therequired distance in m. (minimum value > 3 m.)

Measured sound pressure level (Lp)

The real measured sound pressure level liesbetween Lw and calculated Lp level due to the fol-lowing influence factors:

1. Additional components like oil separators, pipelines, type of drive motor etc. can increase thecalculated sound pressure level Lp.

2. The acoustic data of the engine room. (Thesemust be known before any calculation can beperformed).

3. The stated Lw levels are average levels. It couldbe that at a certain position (motor, oil separatoretc.) higher values can be can be measured



1.2.4.1 SOUND DATA 12

Hint!

For different discharge pressures theindicated sound power level andsound pressure level values have tobe corrected;

Discharge pressure correction factor

C * (Pc-13.5) has to be added to the value in thetable below, where Pc is the discharge pressure inbar(a) and C is a constant which can be taken fromthe correction factor table

Correction factor

Speed (min-1) 740 1000

C(-) 0.68 0.59

Example correction value for different dischargepressure

Compressor type Grasso 612, at speed of 740 min-1

and discharge pressure is 10 bar:

Correction value =0.68 * (10 dB- 13.5 dB) = -2.38 dB;Lw = 95 dB(A) - 2.38 is approx. 93 dB(A)

fig.4: Fictional frame

Sound levels at discharge pressure 13.5 bar(a)

speed Qty cyl.

Sound power level Lw at discharge pressure 13.5 bar

Octave bands OverallPower63 125 250 500 1000 2000 4000 8000

min-1 - dB dB(A)

740

4 82 82 84 89 83 78 79 79 89

6 78 78 93 95 90 82 82 82 95

9 88 87 93 100 92 83 83 82 99

12 90 90 98 106 97 85 85 83 104

1000

4 83 84 89 93 90 83 83 83 94

6 83 84 93 98 95 88 85 84 99

9 83 84 90 102 99 101 87 84 102

12 84 86 100 108 97 97 88 86 107

1.2.5 STARTING TORQUE



The electric motor driving the compressor sometimeshas to be checked for proper starting, especially inthe case of two-stage compressors.For that purpose the "torque - speed characteristic"of the compressor at fully unloaded starting (suctionvalves of all cylinders lifted) is needed. This torqueMa, the trend of which is shown in the figure overleaf,is built up of the following components:

Ml = pull-out torque (or break-away torque), requiredto initiate the movement of the crankshaft after aperiod of compressor standstill. This torque, onlyoccurring at compressor speed zero, is a constantfor each compresor type.

Mw = friction torque, resulting from the purely mecha-nial losses in the crank mechanism. This torque, act-ing during the entire starting period at a constantvalue, only depends on the compressor type and theoil temperature.

Mp = pumping torque, due to the flow resistance inthe lifted suction valves. This torque is zero at zerospeed and increases continuously with speed duringthe starting period, its magnitude being dependenton the refrigerant, the number of cylinders and thesuction pressure according to the formulas:

for single-stage compressors:

Mps = 0.29 x 10-6 (A po + B)z n2 (N.m)

for two-stage compressors:

Mpt = 0.29 x 10-6 [A(zL po + zH pm) + B z]n2 (N.m)

Md = pressure torque, only valid for two-stage com-pressors to counterbalance the pressure differenceacross the HP-pistons. This torque, only occurring atzero compressor speed and depending on the num-ber of HP-cylinders and their disposition relative toeach other, can be written as follows:Md = C(pm - po) (N.m)

Meaning of symbols used:

z = total number of cylinderszL = number of LP-cylinders

zH = number of HP-cylinders

A and B = pumping torque factors, only dependenton the refrigerantC (N.m/bar) = pressure torque factor, only depend-ent on (two-stage) compressor typepo (bar(a)) = suction pressure during compressorstartingpm (bar(a)) = intermediate pressure during compres-sor starting

n (min-1) = compressor speed, increasing from zeroto the chosen nominal operating speed.

The total Ma-curve as a function of the speed n isderived from the components in table below.

The Ma-curve, thus obtained, has to be comparedwith the corresponding torque - speed characteristicof the selected electric drive motor, as supplied bythe motor manufacturer and after being converted tothe compressor shaft by multiplying with the trans-mission ratio D/d, where D and d are the nominaldiameters of the flywheel and the motor pulleyrespectively.In the normal case of a squirrel cage motor with star-delta starter, two torque - speed characteristics Mm(Y) and Mm (Δ) have to be considered as shown inthe Figure 5, page 19.

The difference between Mm and Ma at any speed(shaded area) represents the torque available foraccelerating the combination motor - compressor.The intersection points I and II indicate respectivelythe theoretical switch-over speed from star to deltaand the final unloaded compressor speed.



fig.5: Compressor torque and electric motor torque - speedcharacteristics

Speed inter-val n = 0 0 <= n <= 200/min n >=

200/min

Single-stagecompressors

Ma = MlMa is linear from Ml

to Mw + Mps

Ma = Mw +Mps

Two-stagecompressors

Ma = Ml +Md

Ma is linear from Ml+ Md to Mw + Mpt

Ma = Mw +Mpt

1.2.5.1 COMPRESSOR AND TOR-QUE COMPONENTS



Com

pr.

type

Tota

lnu

mbe

rof

cyl

-in

ders

Num

ber o

f LP

and

HP

cylin

ders

Pull-

out

torq

ue

Fric

tion

torq

ueat

55

°Coi

lte

mp.

Pum

ping

torq

ue fa

ctor

sPr

es-

sure

torq

uefa

ctor

AB

ZZ L

Z HM

I(N

.m)

Mw

(N.m

)N

H3

R13

4aR

22R

404A

R50

7N

H3

R13

4aR

22R

404A

R50

7C

(N.m

/ba

r)

212

2-

-44

31

0.76

24.

875

4.19

35.

100

5.20

90.

155

0.50

00.

511

0.30

00.

178

-

312

3-

-56

36-

412

4-

-65

42-

612

6-

-10

753

-

912

9-

-17

769

-

1212

12-

-23

085

-

2112

32

156

36

0.76

2

4.19

3

0.

155

0.

511

113

3112

43

165

4211

3

4212

64

210

753

24

5112

65

110

753

113

6312

96

317

769

5

7212

97

217

769

113

8412

128

423

085

0

9312

129

323

085

113

1021

212

102

230

8515

6



1.2.6 FREE FORCES ANDMOMENTS

Free forces and moments are inertia forces and theirresulting moments, generated by not fully balancedmasses of the compressor main moving parts(crankshaft, connecting rods, pistons).As indicated in the adjacent figure there can be dis-tinguished horizontal and vertical free forces, calledH and V respectively, both acting in a vertical plane I,which is perpendicular to the crankshaft centre lineat a distance L from the vertical centre plane of thecompressor foot on drive end.Likewise, there are horizontal and vertical freemoments, called Mh and Mv and respectively actingin a horizontal plane II and a vertical plane III, whichboth pass through the crankshaft centre line.Each free force and moment consists of a "primary"component (see table below for the different com-pressor types) with a frequency equal to the com-pressor speed and a "secondary" component with afrequency of double the compressor speed.

fig.6: Planes

Legend

VPI vertical plane I

VPIII vertical plane III

HPII horizontal plane II

F flywheel end of compressor

CF centre line of compressor foot

CL centre line crankshaft

L distance VPI and centre line compressor foot

1.2.6.1 SURVEY

Compr.type

Free forces and moments at com-pressor speed 1000 rpm6

Distanceplain I andcentre linecompres-sor foot L

(mm)

Forces H (horizontal) and V (verti-cal) in (N); Moments Mh (horizon-

tal) and Mv (vertical) in (N.m)7

Primary Secun-dary

212 ForcesH 0 867

147.5V 0 0

6 For different speed n (min-1), all forces and moments haveto be multiplied by (n/1000)2



Compr.type

Free forces and moments at com-pressor speed 1000 rpm6


(mm)


tal) and Mv (vertical) in (N.m)7

Primary Secun-dary

Moments

Mh

91 26

Mv

91 26

3122112

ForcesH 0 919

V 0 306

Moments

Mh

157 32

Mv

157 32

4123112

ForcesH 0 1733

312.5

V 0 0

Moments

Mh

0 0

Mv

0 52

61242125112

ForcesH 0 1838

342.5

V 0 613

Moments

Mh

0 64

Mv

0 64

91263127212

ForcesH 0 0

537.5V 0 0

6 For different speed n (min-1), all forces and moments haveto be multiplied by (n/1000)2

7 1 N = 0.102 kgf = 0.225 lbf; 1 N.m = 0.102 kgf.m = 0.738lbf.ft.

7 1 N = 0.102 kgf = 0.225 lbf; 1 N.m = 0.102 kgf.m = 0.738lbf.ft.

Compr.type

Free forces and moments at com-pressor speed 1000 rpm


(mm)


tal) and Mv (vertical) in (N.m)

Primary Secun-dary

Moments

Mh

0 621

Mv

0 207

12128412931210212

ForcesH 0 0

732.5

V 0 0

Moments

Mh

0 0

Mv

0 0



1.3 LIMITS OF OPERATION ANDFIELDS OF APPLICATION

1.3.1 GENERAL LIMITS AND FIELDSOF OPERATION GRASSO 12

When operating the compressor, none of the limits ofoperation as stated in the table below must beexceeded.8

The diagrams overleaf represent the overall fields ofapplication in which the individual operation limits aretaken into account.

8 In practice, it is not so much the individual operation limitsas combinations of them that are decisive for the condi-tions under which a compressor may operate. To checkthe various possibilities in this respect, use should bemade of the "fields of application" ).



Gen

eral

lim

its a

nd fi

elds

of o

pera

tion

REF

RIG

ERA

NT

NH

3R

22R

134a

R40

4A9

R50

7

Com

pres

sor s

peed

n

min

-1m

in.

500

max

.10

00

Suc

tion

pres

sure

= e

vapo

ratin

g pr

essu

re =

cran

kcas

e pr

es-

sure

1011

p oba

r(a)

min

.0.

3

max

.>=

900

7.0

6.2

6.0

5.8

<900

7.0

Eva

pora

ting

tem

pera

ture

= s

atur

atio

n te

mpe

ratu

re a

t suc

tion

pres

sure

page

24

t o

°C

min

.-5

5.1

-63.

8-5

0-6

8.1

-68.

5

max

.>=

900

+13.

8+1

0.9

+22.

6-0

.1-2

.0

<900

+4.7

+3.9

Suc

tion

supe

rhea

t/int

erm

edia

te s

uper

heat

Δt

°Cm

in.

015

Inte

rmed

iate

pre

ssur

epm

bar(

a)

min

.0.

3

max

.

>=90

0

7.0

6.2

6.0

5.8

>800

<90

07.

07.

0

<=80

08.

28.

4

Inte

rmed

iate

tem

pera

ture

tm°C

min

.-6

8.1

-68.

5

max

.

>=90

0

+13.

8+1

0.9

+22.

6

-0.1

-2.0

>800

<90

0+4

.7+3

.9

<=80

010

.110

.0

Act

ual s

uctio

n te

mpe

ratu

re

t a°C

min

.-5

0

9 Minimum superheat 15 K. Grasso advises a condensing temperature > +35 oC, to avoid condensation of refrigerant in the compressor



Gen

eral

lim

its a

nd fi

elds

of o

pera

tion

REF

RIG

ERA

NT

NH

3R

22R

134a

R40

4A9

R50

7

Dis

char

ge p

ress

ure

= co

nden

sing

pre

ssur

e

pa ge 24 12

p cba

r(a)

max

.24

.0

Des

ign

pres

sure

13ba

r(a)

-26

.5

Con

dens

ing

tem

pera

ture

= s

atur

atio

n te

mpe

ratu

re a

t dis

-ch

arge

pre

ssur

e

t c°C

max

.+5

6.5

+59.

5+7

5.8

+52.

0+5

2.8

Dis

char

ge te

mpe

ratu

re14

t e°C

max

.+1

70

Pre

ssur

e ra

tio p

er s

tage

(pc/p

o or

pc/p

m o

r pm

/po)

15j

-m

in.

1.5

max

.10

15

Pre

ssur

e di

ffere

nce

pa ge 24 16

Δp

bar

max

.17

.5

Oil

tem

pera

ture

in c

rank

case

17t o

il°C

min

.>1

0o C a

nd >

Pcr

ankc

ase

+ 15

K

max

.de

pend

ing

on ty

pe o

f oil

10 For halocarbon refrigerants the maximum values of p0 and t0 are based on a density of the suction gas of 30 kg/m3. In single stageoperation during start-up and immediately thereafter, t0, max may be exceeded slightly and only temporarily. In any case p0 shoulddrop to at least 7 bar(a) within 5 minutes after starting.



9 Minimum superheat 15 K. Grasso advises a condensing temperature > +35 oC, to avoid condensation of refrigerant in the compressor11 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi.12 This pressure is also the maximum allowable pre-set value of the HP safety switch. CAUTION!: When adjusting the HP and/or LP

safety switch, care should be taken that the pressure difference Δp=(pC-po) never exceeds 19.0 bar.13 This pressure deviates from the so called max. discharge pressure=condensing pressure (allowed during operation) as stated in the

table.14 This is the actual discharge temperature, measured directly in the gas flow just before the discharge connection. The given value also

applies to the LP stage of two-stage compressors.15 Pressure ratio limits are not absolute but arbitrary values based on practical considerations.16 The standard built-in overflow safety valve(s) between suction and discharge side has been factory-set to 22.0 ≤ 1.5 bar to prevent

opening during normal operation at Δp = (pc - po) ≤17.5 bar.17 Indicated minimum value is the lowest oil temperature at which the compressor is allowed to be started. The maximum oil temperature

depends on the operating conditions of the compressor, the oil type used and (for halocarbon refrigerants only) the solubility of therefrigerant in the oil. A minimum actual oil viscosity of 10 cSt is always required.



1.3.2 PRECISE FIELD OF APPLICA-TION

Hint!

The field of application diagrams asshown in this manual can vary slightlyfrom the actual field of application foreach particular selection.The actual field of application isdependent on refrigerant, type of com-pressor, speed, suction superheat,partload steps (different pressureratios) and interstage cooling system.Always consult Grasso"s softwareprogram, COMSEL, to determine theprecise field of application for anactual compressor selection.

1.3.3 FIELDS OF APPLICATION SIN-GLE-STAGE AND BOOSTER

General

Application of part-load operation for a long period oftime and/or superheat > 0 K results in higher dis-charge temperatures. Consequently the fields ofapplication for single-stage and booster compressorswill be reduced. So line te-max will shift downwards forNH3.

Symbols used in diagrams

to = evaporating temperature

po = evaporating pressure

tc = condensing temperature

pc = condensing pressure

Δto = suction superheat

j = pressure ratio = (pc / po)

Δp = pressure difference = (pc - po)

te,max = maximum discharge temperature

↓ = Line shift downwards for Δto > 0 K and/orpart-load operation

Procedure and data

• Diagrams in are based on continuous full-loadoperation, suction superheat = 0 K for NH3

• For continuous minimum part-load (i.e. morethan 30 minutes) consult Grasso.



1.3.3.1 FIELDS OF APPLICATION

fig.7: Fields of application halocarbons



1.3.4 FIELDS OF APPLICATION TWOSTAGE

General

The fields of application for two stage compressorsare (besides superheat and part-load operation) verydependant on ϕ(ratio LP/HP swept volume; full-loadand part-load can have different values). Becauseeach capacity control step can have a different ϕ, it isvery important to check for every control step (espe-cially during starting up!) that the compressor will runwith-in its limits of operation.

Hint!

Refer to Starting Up Procedure andLimitations of Partload Operation (Sec-tion 1.3.5, page 31/Section 1.3.6,page 31)

Symbols used in diagrams

to = evaporating temperature

po = evaporating pressure

tc = condensing temperature

pc = condensing pressure

tm = saturation intermediate temperature

j = pressure ratio = (pc / po, pc / pm or pm / po)

Δp = pressure difference = (pc - po)

te,max = maximum discharge temperature

teH,max = maximum discharge temperature HP

ϕ = ratio LP/HP swept volume (full-load and part-load can have different values)

↓ = Line shift downwards for Δto > 0 K and/orpart-load operation

Procedure and Data

• Two stage fields of application are variabledepending on types of compressors and/or part-load steps.All compressor types are included within the totalfield of application.

• Diagrams overleaf are based on LP and HP suc-tion superheat 0 K.

• Warning!

For continous part-load (i.e. more than30 minutes) consult Grasso.

• The Dummy diagram shows field of applicationfor different ϕ"s.

• Shaded areas are fields of single-stage opera-tion (used and allowed only during starting upcompressor).

• Each ϕ has its own field of application (Example;see dummy diagram ϕ= X area)

• ϕ = 0 capacity control step to be used duringstarting up compressor only. Refer to starting upprocedure (Section 1.3.6, page 31)

• ϕ = 1 is "Fast Pull Down" capacity control step(option), to be used during starting up compres-sor only. Refer to starting up procedure (Sec-tion 1.3.6, page 31)



fig.8: Dummy diagram

Dummy Diagram; Explanation two stage field of application

Legend

Jmax / te,max

Area on the right side of this line indicates thesingle stage field of operation (starting up).This line shifts down in case of continuouspart-load operation and/or (intermediate)

superheat. Superheat also results in limitedpart-load operation.

teH,max / te,max

Maximum HP-discharge temperature . Thisline shifts down in case of continuous part-load operation and/or (intermediate) super-heat. Superheat also results in limited part-

load operation.

ϕ

Each ϕ (phi) has its own field of appication.The higher this value, the lower possible

evaporating temperature. For each capacitycontrol step field of application must be veri-

fied in relation with ϕ.

Po,min Minimum suction pressure (evaporating)

tm,max Maximum intermediate pressure.

LP/HP cylinder ratio (ϕ ) field of appication

Each ϕ value has it's own field of application.When ϕ value increases (by changing a capacitycontrol step) the intermediate pressure will increase.Then the discharge pressure LP will increase andthe discharge pressure HP will decrease.When ϕ value decreases (by changing a capacitycontrol step) the intermediate pressure will decrease.Then the discharge pressure LP will decrease andthe discharge pressure HP will increase.For each ϕ value all limits of operation have to betaken into account

1. Maximum discharge temperatures LP cylinders

2. Maximum discharge temperatures HP cylinders

3. Maximum intermediate pressure

4. Maximum suction pressure

5. Maximum pressure difference LP cylinders

6. Maximum pressure difference HP cylinders

7. Maximum pressure ratio LP cylinders

8. Maximum pressure ratio HP cylinders

Hint!

All these values are taken into accountby the GSC controller

1.3.4.1 FIELDS OF APPLICATIONDIAGRAMS

fig.9: Field of application two-stage NH3

fig.10: Field of application two-stage R404A and R507



fig.11: Field of application two-stage R22

1.3.5 LIMITATIONS OF PART-LOADOPERATION

Limitations of part-load operation for single-stage compressors

In the case of continuous single-stage part-loadoperation of Grasso compressors with the refrigerantNH3, not all standard capacity control steps can beused under all operating conditions. There is a limita-tion with respect to minimum capacity, which,depending on the amount of suction superheat, isdetermined by the maximum discharge temperatureof 170 °C. This means that the full-load field of appli-cation as shown in the NH3- diagram, is reduced attop-left for part-load operation in a way as indicatedby the arrows in the the relevant diagram.This part-load restriction cannot be eliminated byapplying a cooling system on the cylinder head.

Warning!

In general the rule is that, irrespectiveof refrigerant and conditions of opera-tion, it is never allowed to run a com-pressor during a prolonged period oftime fully unloaded, i.e. with all cylin-ders switched off.

When using a Grasso compressor equipped with astandard capacity control such a situation is impossi-ble because then, apart from the starting period,always one or more cylinders are permanently con-nected to the control oil pressure.

Limitations of part-load operation for two-stagecompressors

From the diagrams, it appears that for two-stagecompressors the field of application depends notonly on the kind of refrigerant but also on the ratio ϕof L.P. and H.P. swept volume.

This means (since the standard capacity controlsteps of the individual two-stage types have notalways the same ϕ-value) that for the successivecapacity control steps of a certain compressor typedifferent fields of application may be valid. If this isthe case, the situation may occur that, when cylin-ders are switched on or off under constant (design)conditions of operation, the corresponding workingpoint (= combination of condensing temperature tcand evaporating temperature to) lies outside one ormore of the relevant fields of application.This implies that it is not allowed to use the part loadsteps concerned, either on account of too high aH.P. discharge temperature in case of NH3 only(working point lies to the left of the field of applica-tion), or on account of too high a saturation inter-mediate temperature / intermediate pressure (work-ing point to the right of the field of application). In thecase of electrical capacity control, such disallowedpart-load steps can easily be avoided in actual prac-tice by adapting accordingly the wiring diagram forenergising the three-way solenoid valves.

Warning!

Electrical capacity control is manda-tory for two-stage compressors.Apart from the above-mentioned inad-missibility of certain standard part-load control steps, care should alwaysbe taken to ensure that the capacity oftwo-stage compressors is neverreduced to such an extent that onlyH.P. cylinders remain operative.

For then the compressor would operate as a single-stage machine, but under two-stage conditions,which would result, in particular for NH3, in an unac-ceptably high discharge temperature. This restrictionmeans that the three-way solenoid valves should bewired so that, when the compressor is running underdesign conditions, at least one solenoid valveremains energised.

1.3.6 STARTING UP OF TWO-STAGECOMPRESSORS

Procedure for starting from compressor stand-still

In the case of two-stage compressors it is veryimportant that immediately after the period of auto-matic fully unloaded start (ensured by the corre-sponding three-way solenoid valve in the controlpressure supply line from the oil pump; only one or



more H.P. cylinders become operative, viz. onlythose cylinders of which the suction valve liftingmechanism is directly and permanently connected tothe control pressure supply of the oil pump via thestarting solenoid valve mentioned. This means thatduring starting none of the three-way solenoid valvesfor the capacity control are allowed to be energized.

Procedure to move on to two-stage operationand to increase capacity.

Once properly started, as indicated in the previousparagraph, the compressor has to be switched overto two-stage operation with minimum capacity, fol-lowed, if and when required, by gradual stepping upto maximum capacity.The procedure thereby to be applied depends on theinstallation operating conditions during starting whichgive rise to two distinct possibilities, viz.:

1. The compressor is started at low evaporatingtemperatures, this being approx. the (design)value during normal (full-load) operation.This situation occurs after the compressor hasbeen stopped for a certain period of timebecause of low capacity requirements of theinstallation. Under these circumstances it is per-mitted to switch over to the two-stage part-loadstep of minimum capacity immediately afterproper starting with H.P. cylinders in operation.In the case of NH3, this is even a necessity, forotherwise the compressor would be running insingle-stage under two-stage conditions, result-ing in too high a discharge temperature.

2. The compressor is started at a relatively highevaporating temperature, that is to say muchhigher than under design conditions and in anycase not suitable for two-stage operation.Such a situation may occur after a prolongedperiod of compressor standstill or when the com-pressor operates on a batch type freezing tunnel,just loaded with warm products. Under these cir-cumstances it is not permitted to switch over totwo-stage operation with minimum capacity untilthe H.P. cylinders already in operation have low-ered (in single-stage) the evaporating tempera-ture so that the corresponding working point atthe condensing temperature tc, lies inside thefield of application of the two-stage minimumpart-load step concerned. Only then, after thisstep has been energized, the saturation inter-mediate temperature tm will be below its maxi-mum value. Consequently, the maximum value

of to at which it is allowed to switch over to two-stage operation, is determined by the intersec-tion of the near-vertical line which represents theright hand limitation of the relevant field of appli-cation and the horizontal line which representsthe condensing temperature tc.

Likewise, during further stepping up to maximumcapacity, the evaporating temperature has to bepulled down by each intermediate part-load stepso far that the corresponding working point atgiven condensing temperature lies each time justinside the field of application of the next part-loadstep of higher capacity, before that step is ener-gized.

Fast pull-down part-load control steps

When using the standard capacity control steps ofthe two-stage compressor types, the pull-down pro-cedure to achieve full-load operation at design condi-tions, as described in the previous paragraph, israther often very time consuming. This is due to thefact that all compressor types are always started withonly one HP cylinder in operation and that the mini-mum LP/HP swept volume ratio for any part-loadstep is ϕ = 2.Therefore, for all Grasso two-stage types a fast pull-down electric capacity control system has beendeveloped, which allows the compressors to be star-ted with two or more HP cylinders in operation andwhich includes one or more part-load steps with vol-ume ratio ϕ = 1.



1.4 LUBRICATING OILS (choice andrecommendations)

Warning!

The choice of oil for a refrigerationcompressor should be made by takinginto account the entire refrigerationsystem design and operation as wellas the operating conditions of thecompressor.

For lubrication of refrigeration compressors, severalbrands and types of specially developed lubricatingoils are on the market. The choice of oil depends notonly on its good lubrication properties (viscosity) andchemical stability at the operating conditions of thecompressor, but also on the operating conditions ofthe refrigerating plant (solidifying and floc point, solu-bility).

Grasso has tested and approved for use in its recip-rocating-compressors the brands and types of oil aslisted tables below.The choice of the lubricating oil depends on type ofrefrigerant and the operating conditions of the com-pressor.The oil viscosity should always be more than 10 cSt.Assumed is that the oil temperature at the bearingsurfaces = 15 K above crankcase oil temperature.A higher ISO-VG number should be chosen whenrefrigerant solubility in crankcase is expected to behigh especially in case of HCFC’s and HFC’s.

OIL SELECTION PROCEDURE:Use the oil viscosity selection table to select oil vis-cosity required. The following page lists all oilsapproved by Grasso for reciprocating compressors.

1.4.1 OIL SELECTION TABLE

18 to,max is the saturated temperature, corresponding to maxi-mum crankcase pressure where at the usual oil tempera-tures the oil/refrigerant mixture has a viscosity of > 10 cSt.

Oil selection table

Refrigerantused

Max. allowableevaporatingtemperatureto,max (°C)18

ISO VG-number, accordingto ISO 3448

46 68 100

NH3 - v v v

HCFC’s(R22)

-50 v

-30 v v

-20 v

-10 v v

0 v

+10 v

HFC’s(R134a,R507,

R404A)

-50 v v

-30 v v

-20 v v

-10 v v

0 v

+10 v

For all other refrigerants contact Grasso

Legend v Approved by Grasso

1.4.1.1 REMARKS

1. Using ISO VG100 oils to increase viscosity athigh expected cranckcase-temperatures makesno sense as the friction-heat will increase thatmuch, that the oil-temperature limit related to theminimum viscosity of 10 cSt will also be excee-ded. Only in case of expected high refrigerant-concentrations in the cranckcase this viscosity-gradeoil is an alternative!



2. Using ISO VG46 oils to meet low pour pointrequirements is only acceptable if coupled to ahigh viscosity-index of at least 100, otherwise theworking limits are so limited (again concerningthe minimum required oil-viscosity of 10 cSt) thatit can be used in medium evaporation-pressures,making no sense to use them als a low pourpointalternative!

Hint!

Some of the oil types listed in thetables may be marketed under othernames and/or designations; these oilscan also be used, provided their iden-tity can be proved beyond any doubt.Application of other/alternavive oils isnot permitted without the written con-sent of Grasso.

1.4.2 STRONGLY RECOMMENDEDOIL TYPES

Strongly recommended oil types for Grasso reciprocatingcompressors

Refriger-ant used Brand Type designation Food

Grade

NH3

CPI CP-1009-68 H2

PETRO CAN-ADA

Reflo 68AReflo XL

H2H2

Klüber Summit RHT-68 H2

TEXACO Capella Premium68 -

SHELLClavus S-68 /

Refrigeration OilS2 FR-A19

-

19 Old name resp. new name; old name will be phased-outduring 2010.



1.4.3 ACCEPTED NH3 AND HCFCOIL TYPES

Accepted NH and HCFC (e.g. R22) oil types for Grassoreciprocating compressors

Brand Type designation ISO VGnumber20

FoodGrade

AVIAFC 46 44 -

FC 68 65 -

BPEnergol LPT-F 46 54 -

Energol LPT 6821 68 -

CASTROL Icematic 299 56 -

CPI CP-1009-68 69 H2

EXXON MOBIL

Zerice S46 48 -

Zerice S68 68 -

Arctic 300 68 -

FUCHSReniso KS 46 47 -

Renisso KC 68 68 -

KROON OIL Carsinus FC 46/68 46 -

PETRO CAN-ADA

Reflo 68A22

Reflo XL58

H2H2

Kuwait Petro-leum Q8 Stravinsky C 55 -

SHELL

\ -

-

46 -

68 -

Refrigeration OilS2 FR-A 68 -

20 Viscosity grade number designation according to ISOStandard 3448.

21 Not miscible with R22 at low temperatures22 NH3 only

Accepted NH and HCFC (e.g. R22) oil types for Grassoreciprocating compressors

Brand Type designation ISO VGnumber

FoodGrade

95 -

SUN-OIL

Suniso 3.5 GS 43 -

Suniso 4 GS 55 -

Suniso 5 G 94 -

Suniso 4 SA 57 -

TEXACO

Capella WF 68 65 H2

Capella Premium68 67 -

TOTAL Luneria FR 68 68 -

Klüber Summit RHT-68 68 H2



1.4.4 ACCEPTED HFC OIL TYPES

Accepted HFC (e.g. R134a, R404A, R407c, R507) oil typesfor Grasso reciprocating compressors

Brand Type designation ISO VGnumber23

CASTROLIcematic SW 68 67

Icematic SW 100 100

CPISolest 68 64

Solest 120 131

TOTALACD 68 M 70

ACD 100 FY 98

FUCHSReniso E 68 68

Reniso E 100 100

ICIEmkarate RL 68H 68

Emkarate RL 100H 100

EXXON MOBIL EAL Arctic 68 63

SHELL

Clavus R68 /Refrigeration Oil S4 FR-F 68

66

Refrigeration Oil S4 FR-F100 94

TEXACO

Capella HFC 55 52.5

Capella HFC 80 80

Capella HFC 120 118

23 Viscosity grade number designation according to ISOStandard 3448.



1.5 DESIGN DETAILS OF COMPRES-SOR

1.5.1 COMPRESSOR HOUSING

The compressor housing is of welded steel construc-tion and comprises the crankcase, the cylinder jack-ets, the suction manifold and the discharge line. Inthe lower part of each cylinder jacket, an inter-changeable cylinder liner is provided.The annular space between cylinder liner and jacketserves as suction chamber. The discharge chamberis formed by the upper part of the cylinder jacket shutoff by the cylinder head cover.

The crankshaft runs in bearing covers at either endof the crankcase which also carries the rotary shaftseal housing and the oil pump housing. In the caseof compressors whose crankshaft is provided withintermediate bearings, one or more supports for thebearing blocks are welded in the crankcase.

A certain level of oil is always contained in the crank-case for lubrication purposes.To determine the oil level, a sight glass is located onthe oil pump end of the compressor.All compressors are fitted with a crankcase heaterconnection.

The oil which is separated in the suction chamberfrom the refrigerant vapour can flow back to thecrankcase via a small orifice inside a plug. This plugis fitted between suction chamber and crankcase inthe lower supporting ring of the cylinder liner. Theplugs fitted in the HP-cylinders of two-stage com-pressors are not provided with an orifice.

The crankcase interior is accessible via service cov-ers provided on both sides of the crankcase.



1.5.1.1 DIAGRAMS

fig.12: Design of bare compressor (Grasso 612)

Legend

1 Shaft seal housing 17 Suction gas filter housing

2 Rotary shaft seal 18 Plug with oil return orifice

3 Bearing cover (driveend) 19 Bearing cover (oil pump

end)

4 Connecting rod 20 Thrust bearing

5 Crankcase 21 Oil pump

6 Piston 22 Oil pump housing

7 Valve lifting control cyl-inder 23 Oil discharge filter

8 Cylinder liner 24 Plugged off connectionfor crankcase heater

9 Suction and dischargevalve assembly 25 Oil charge and drain

valve

10 Buffer spring cup 26 Sleeve for heating ele-ment

11 Cylinder jacket 27 Oil supply line

12 Buffer spring 28 Crankshaft

13 Cylinder head cover 29 Intermediate bearing

14 Suction manifold 30 Oil intake line

15 Valve lifting mecanism 31 Counterweight

16 Suction connection



aaaaaaaaaaaaaaaaaaaaaaaa

fig.13: Design of bare compressor (Grasso 612)

Legend

5 Crankcase 32 Discharge line

7 Valve lifting control cyl-inder 33 Discharge connection

11 Cylinder jacket 34 Suction gas filter

13 Cylinder head cover 35 Service cover

16 Suction connection 36 Oil sight glass

17 Suction gas filter hous-ing 37 Oil suction filter

22 Oil pump housing 38 Relief valve

23 Oil discharge filter 39 Lubricating oil pressureregulator

24 Plugged off connectionfor crankcase heater 40 Control oil pressure regu-

lator

25 Oil charge and drainvalve

1.5.2 CYLINDERS AND MOVINGPARTS

The cylinders are formed by interchangeable, centri-fugally cast iron cylinder liners pressed into the cylin-der jackets. The collar on top of the cylinder liner isprovided with openings and acts as a seat for thesuction valve ring.In the cylinder liners aluminium alloy pistons arelocated, on which compression rings and 1 oil scra-per ring are fitted.

The connecting rods have a split-type big end, inwhich precision bearing shells are positioned.The gudgeon pin is mounted in the small end of theconnecting rod on a bronze bush or, in the case ofHP cylinders of two-stage compressors, two needlebearings are pressed into the small end bore.

The nodular cast iron crankshaft is mounted insleeve bearings consisting of interchangeable, one-piece bushes pressed into the bearing covers.Intermediate bearings are built up of split-type bear-ing shells located in bearing blocks.

The axial force of the crankshaft is taken up by athrust bearing on the oil pump end, consisting of arotational steel disc, fitted onto the crankshaft, and astationary steel ring. The sliding surface of this ring iscoated with a wear-resistant layer and has sepa-rately fed oil chambers.

The crankshaft is dynamically balanced. The shaftend has a key, for securing flywheel or coupling andis carried by the main bearing.

1.5.3 ROTARY SHAFT SEAL

In order to maintain gastightness, the compressor isprovided with a special rotary shaft seal, the parts ofwhich are retained in a housing mounted against thebearing cover on the driving end.

The seal between rotating and stationary parts iseffected by the sliding surface between a stationaryring fitted in the shaft seal housing and a rotating slipring fitted on the crankshaft.For this purpose the sliding surface of both slip ringsare ground to extreme finish and lapped.

The slip ring is carried by the slip ring holder andforms an integral part of the rotary seal assembly.This assembly consists of the slip ring holder withinsert, a metal bellows and a drive collar.

O-rings are provided to ensure the sealing betweenthe rotary seal assembly and shaft seal housing andbetween the counter-slip ring and crankshaft.

To remove frictional heat developed by the slip rings,the shaft seal is incorporated in the relatively coolmain stream of the lubricating oil circuit.



1.5.3.1 ROTARY SHAFT SEAL

fig.14

Leg-end

1 Crankshaft

2 Bearing bush

3 Bearing cover

4 Shaft seal housing

5 Stationary counterslip ring

6 Rotary seal assembly

6a Slip ring holder with insert

6b Metal bellows

6c Drive collar

7 Grub screw

8 O-rings

9 Oil leakage drain of rotary shaft seal

A Internal lubricating system

B Cool and clean lubricating oil, direct from oil pump

1.5.4 SUCTION AND DISCHARGEVALVES

The suction and discharge valves of the compressorcontain valve rings, kept in closed position underspring tension. The lift of the valve rings is limited bythe stroke limitor.

The suction valve consists of one valve ring and oneor more sinusoidal springs, mounted between thecollar of the cylinder liner and the outer dischargevalve seat. The collar integrates the suction seatsand the valve guide. The discharge valve seat isused as stroke limiter of the suction valve.

The discharge valve consists of one or more valverings and sinusoidal springs and a stroke limiter. Thevalve plate is bolted to the stroke limiter with the cen-tral bolt.The whole discharge valve (the so called “dischargevalve assembly“) is pressed down by bufferspring(s), which prevents serious damage in thecase of the presence of liquid in the suction gas.



1.5.4.1 DIAGRAM SUCTION ANDDISCHARGE VALVES

fig.15: Suction and discharge valve assembly

Leg-end

1 Spring retainer

2 Buffer spring

3 Discharge valve rings and springs

4 Spring cup/Discharge valve stroke limitor

5 Discharge valve seat/Suction valve stroke limitor

6 Suction valve ring and springs

7 Cylinder liner/suction valve seat

8 Orifice to return oil to crankcase

1.5.5 VALVE-LIFTING MECHANISM

fig.16: Valve-lifting mechanism

Legend

1 Pressure ring

2 Tie bolt

3 Spring

4 Supporting ring

5 Semi-circular lever

6 Suction valve ring

7 Push pin

8 Piston housing

9 Stem

10 Piston

11 Bore for pressure equalizing

12 Control oil pressure

Hint!

Picture shows cylinder in operation(suction valve ring not lifted)



In order to enable the compressor to start fully unloa-ded, all cylinders are put out of action mechanicallyby suction valve ring lifting during compressor stand-still. For this purpose a pressure ring is provided ineach cylinder, which can move up and down aroundthe cylinder liner. The pressure ring is provided atthe top with push pins capable of lifting the suctionvalve ring from its seat via openings in the collar ofthe cylinder liner.On the lower part of the liner a supporting ring is fit-ted, to which a semi-circular lever is hinged. Thislever is controlled via a stem provided in a housingon the outside of the cylinder jacket. The piston canbe moved inwards by control oil pressure from the oilpump. On the other side, the lever is connected tothe pressure ring by two tie bolts passing through thesupporting ring. Both tie bolts are surrounded by aspring provided between supporting ring and pres-sure ring.At compressor standstill there is no control oil pres-sure and the pressure ring is forced upwards by thesprings, causing the push pins to keep the suctionvalve ring lifted and the control piston is forced out-wards by the lever.

After the compressor has been started, control oilpressure is not admitted to the control pistons until asignal is received from the delta switch of the star/delta starter. This signal enables the control oil pres-sure solenoid valve to energize and permit oil pres-sure through to one or more control pistons. The pis-ton moves inwards, so that the lever tilts and pullsthe pressure ring with push pins downwards againstspring tension via the tie bolts. The suction valve ringthen descends on to its seat and the cylinder is inoperation.

Hint!

Because there is only oil pressureafter the compressor has been started,fully unloaded starting of the compres-sor is ensured, i.e. ALL suction valvesrings are lifted.

A small bore for pressure equalization is madebetween the crankcase and the control piston cylin-der bore, which enables the piston to move inwards.

The valve-lifting mechanisms are also used forcapacity control by succesively cutting in or out cylin-ders or cylinder groups, which are controlled eithermanually or electrically.

1.5.6 PRINCIPAL CONNECTIONS,GAS SUCTION FILTER ANDPRESSURE EQUALISING

The suction and discharge chambers of the separatecylinders are connected, via one or more lines, into asingle suction and discharge connection with flange,with which the compressor is coupled to the refriger-ating plant via stop valves.The (LP) suction connection is fitted on the horizon-tal suction filter housing at the oil pump end of thecompressor, in which one or two removable suctionfilters are provided for filtering the intake refrigerantgas. In the case of two-stage compressors, an extraLP discharge and HP suction connection is provided,which can be interconnected via an interstagecooler.The HP suction connection requires an externallymounted suction gas filter (available as an accessoryfrom Grasso).Between suction filter housing and crankcase anequalizing line is provided in order to prevent thecrankcase pressure from rising due to piston leak-age. Consequently, the crankcase pressure is equalto suction pressure for single-stage as well as fortwo-stage compressors. All principal connectionshave nipples for connecting the lines of pressuregauges and pressure safety switches or in case ofan electronic control device for connecting the linesof pressure and temperature sensor elements.

1.5.7 RELIEF VALVES

In order to prevent excessive pressure difference inthe compressor, one or more relief valves (depend-ent on compressor type) are provided.

In case of single-stage compressors these counterpressure dependent type of relief valves act on thedifference between discharge and suction pressure.

In case of two-stage compressors counter pressureindependent type of relief valves will always beapplied on LP-stage and HP-stage.

To comply with certain regulations a counter pres-sure independent type of relief valve is available(optional).

The valves are fitted externally against the crank-case housing. The relief valves are spring-loadedvalves adjusted at the works.

1.5.8 HEAVY DUTY THRUST BEAR-ING CONSTRUCTION



In addition to the standard design there is an alterna-tive "heavy duty" roller thrust bearing available forcertain applications and consists of a twin type rollerassembly. One main bearing for the outward pull ofthe crankshaft and a second one for inward push ofthe crankshaft during vacuum operation. The totalassembly is pre-loaded by means of springs toensure proper running conditions are achieved.

Hint!

Compressors fitted with roller thrustbearings can be easily recognised byan external oil overflow line runningfrom the oil pump to one of the crank-case covers and a marking on the topof the oil pump. (Compressors fittedwith the standard thrust bearingarrangement have an internal overflowback to the crankcase and no marking)

1.5.8.1 EXPLODED VIEW HEAVYDUTY THRUST BEARING

fig.17

Legend

1 Housing washer 7 Thrust washer

2 Needle thrust bearing 8 Spring retainer

3 Bolt 9 Spring

4 Hold down disk 10 Carrier disk

5 Shaft washer 11 Bearing cover

6 Cylindrical roller thrustbearing

1.5.9 OIL PUMP AND FILTERS

The direct-driven oil pump is fitted on the bearingcover opposite the compressor driving end. The oilpump housing accommodates the pump elementand two adjustable oil pressure regulators.The oil pump supplies, besides the lubricating oilpressure, a separate control oil pressure for actuat-ing the valve-lifting mechanisms, mounted on eachcylinder to obtain unloaded starting and for capacitycontrol.

The oil suction and discharge filters are fitted exter-nally to the oil pump housing. The filter elements arespring-mounted inside their housings. In case thepressure difference over the filter element exceedsthe maximum value, the filter element will be liftedfrom its seat against spring pressure and the oil by-passes the filter element.



fig.18: Oil pump, oil filters and oil pressure regulators

Leg-end

1 Oil suction filter

2 Oil discharge filter

3 Pump element

4 Oil pump housing and bearing cover

5 Lubricating oil pressure regulator

6 Control oil pressure regulator

A Oil suction from crankcase

B Control oil pressure to valve lifting mechanisms forunloaded starting and capacity control

C Return of excess oil to crankcase

D Oil discharge to shaft seal and lubrication system viainternal line

1.5.9.1 OIL PUMP AND THRUSTBEARING

fig.19: Oil pump and thrust bearing

Leg-end

1 Bearing cover

2 Stationary thrust bearing ring coated with a wearresistant layer

3 Steel disk rotating with crankshaft

4 Oil pump element

5 Oil pump housing

6 Oil discharge filter housing

A Measure point of oil pressure at the end of lubricationsystem

B From lubricating system

C Return of excess oil to crankcase via internal bore

D Internal line for oil supply to shaft seal and lubricationsystem



1.5.10 CONTROL AND LUBRICATIONOIL SYSTEM (Figure 18,page 44 and Figure 20,page 45)

fig.20: Control and lubricating oil system

1 Oil suction filter

2 Oil pump

3 Control oil pressure regulator

4 External oil pressure line(s) to valve lifting mechanism(s)

5 Piston housing of valve lifting mechanism

6 Lubricating oil pressure regulator

7 Oil discharge filter

8 Internal oil pressure line for oil supply to shaft seal andlubrication system

9 Shaft seal housing

10 Measure point of oil pressure at the end of lubrication sys-tem

11 Thrust bearing

12 Oil sump

A Control oil pressure

B Oil lubricating pressure

C Crankase pressure

The oil is drawn from the crankcase via the oil suc-tion filter. The pressures delivered by the pump arecontrolled by a control oil pressure regulator togetherwith a lubricating oil pressure regulator at the begin-

ning of the lubrication system just before the oil dis-charge filter.The pump discharge pressure, which is the controlpressure is determined by the built-in control oil pres-sure regulator; excess oil flows to the lubricating oilpressure regulator. This regulator acts as relief valvefrom which excess oil is returned to the crankcase.The oil available between the control oil pressureregulator and lubricating oil pressure regulator flowsto the lubrication system via the oil discharge filter.The lubrication of the compressor is effected underpressure. The pump delivers the oil via a dischargefilter and an internal oil supply line to the shaft sealhousing.From this housing the oil flows into the crankshaft, inwhich a continuous oil channel has been drilled, pro-vided with radially drilled oilways to the bearings.

The connecting rods also have an internal oil chan-nel through which the oil is supplied to the small endbearings. Sufficient lubrication of the cylinder walls isensured by splash lubrication.

The thrust bearing at the oil pump end of the crank-shaft is also lubricated.

As well as its lubricating function, the oil also has acooling function, especially for the rotary shaft seal,consequently the amount of circulating oil is consid-erably more than that required for lubrication. Thisexcess oil is fed back into the crankcase via four oilways in the stationary thrust bearing ring and a sepa-rate bore inside the bearing cover.A connection for measuring the lubricating oil pres-sure at the end of lubrication oil system is located atthe outside of the bearing cover just above the oilpump housing.



2 DESCRIPTION AND SELECTION OF ACCESSORIES

2.1 CAPACITY CONTROL SYSTEMS

2.1.1 CAPACITY CONTROL SELEC-TION

One of the options must be applied;

• Electric (compulsory for two-stage compressors);

• Standard (recommended for single-stageand booster compressors)

• "Fast pull down" (FPD); obligatory for R404Aand R507 applications; recommended for alltwo-stage compressors

• Manual (Not allowed for two-stage compressors)

Hint!

In case manual or electric capacitycontrol is applied, fully unloaded start-ing of the compressor is ensured.

2.1.2 PART-LOAD POWER CON-SUMPTION AND ALLOWEDPART LOAD STEPS COMSEL

To determine the allowed partload steps for thedesign conditons and the corresponding partloadpower consumption refer to software program Com-sel.

2.1.3 SURVEY CAPACITY CONTROLSYSTEMS AND UNLOADEDSTART

General

Capacity control of the compressor will be enabledby raising and lowering the suction valves, by meansof the control oil pressure from the oil pump. One ofthe options mentioned below is compulsory.

2.1.3.1 START AND STOPPINGPROCEDURE SINGLE FIXEDSPEED COMPRESSORS

In order to guarantee all cylinders are fully unloadedduring starting the following procedure must be fol-lowed:

Starting

Fully unloaded compressor starting is enabled byenergising the solenoid valve for unloaded starting.This is a Normally Open (NO) valve in contrast with

the solenoid valves for capacity control which areNormally Closed (NC).This NO-solenoid valve has to be energised 20 sec-onds before starting the compressor motor. The NO-solenoid has to be de-energised between 10 and 20seconds after starting the compressor motor to ena-ble the motor the required speed and the compres-sor to develop the required oil pressure.In the case of single-stage compressors, the NO-sol-enoid valve controls the minimum required cylinders,these cylinders should always be activated duringoperation unless the limits of application and systembalance demand otherwise.In the case of two-stage compressors, HP cylindersonly are activated during starting which, however, donot at the same time represent the minimumcapacity. The other cylinders can be energised orde-energised in one or more steps in a standardsequence for each type of compressor within the lim-its of operation and system balance.

Stopping

For a smooth stopping procedure, de-energise theNC solenoid valves step by step to the minimumcapacity (remark, For two stage compressors do notrun on only HP cylinders) then the NO-solenoid valvemust be activated 5 seconds before stopping thecompressor. Keep the solenoid valve open until thecompressor has fully stopped.

2.1.3.2 GUIDE LINE FREQUENCYCONTROL

Hint!

For frequency controlled machinesrefer to separate instruction "Guideline frequency control 00.87.041"

Start-up procedure

In order to guarantee all cylinders are fully unloadedduring starting the following procedure must be fol-lowed:Fully unloaded compressor starting is enabled byenergising the solenoid valve for unloaded starting.This is a Normally Open (NO) valve in contrast withthe solenoid valves for capacity control which areNormally Closed (NC).This NO-solenoid valve has to be energised 20 sec-onds before starting the compressor motor. The NO-solenoid has to be de-energised between 10 and 20



seconds after starting the compressor motor to ena-ble the motor the required speed and the compres-sor to develop the required oil pressure.In the case of single-stage compressors, the NO-sol-enoid valve controls the minimum required cylinders,these cylinders should always be activated duringoperation unless the limits of application and systembalance demand otherwise.In the case of two-stage compressors, HP cylindersonly are activated during starting which, however, donot at the same time represent the minimumcapacity. The other cylinders can be energised orde-energised in one or more steps in a standardsequence for each type of compressor within the lim-its of operation and system balance.

Acceleration time from zero to the so-called "mini-mum starting speed" (as mentioned in the compres-sor specification) should be 4 - 6 seconds to build upoil pressure. (The minimum starting speed may varyaccording to compressor type) Reduce the speed to"minimum allowable running speed" according toproduct information. At this minimum speed the cylin-der capacity control system can become operational.Minimum speed will remain as cylinders are activa-ted. When all cylinders are loaded the speed controlcan become operative.

Running:During running the compressor speed is allowed tovary between the boundaries as given by the manu-facturer. Depending on compressor model, runningconditions and chosen motor drive line "black spots"(critical speeds) may occur. It is not allowed to run inthe critical speed area. The passing time should nottake longer than 6 seconds and, ideally, less than 4seconds To maintain stable running conditions theacceleration and deceleration times between mini-mum and maximum speed should be, preferably, asslow as possible.

Remarks:

1. Between the minimum and maximum speeds allcylinders must be fully loaded unless otherwisestated by the manufacturer.

2. Only at the lowest allowable speed can cylindercapacity steps be regulated, unless otherwisespecified. Keep compressor with the limits ofapplication.

3. Maximum Frequency should be set in the soft-ware to prevent exceeding the maximum allowa-ble speed!

Stop procedure

1. Reduce the compressor to the minimum allowa-ble speed with all cylinders in operation.

2. De-energise the NC solenoid valves step by stepto the minimum capacity (remark, For two stagecompressors do not run on only HP cylinders)then the NO-solenoid valve must be activated 5seconds before stopping the compressor. Keepthe NO-solenoid valve open until the compressorhas fully stopped.

2.1.4 WIRING LOGIC NORMALLYOPEN UNLOADED START SOL-ENOID

1. If compessor is NOT running then NO-solenoidis not energised.

2. Energise the NO-solenoid 10 - 20 secondsbefore starting.

3. If compressor starts then NO-solenoid is ener-gised and de-energised by means of an auxiliarytime relay.

4. Ensure that the NO-solenoid valve is not de-energised until full speed has been achieved andthe specified lubrication oil pressure has beenestablished.

5. Energise the NO-solenoid 5 seconds beforestopping until the compressor is stopped com-pletely.



2.1.5 ELECTRIC CAPACITY CON-TROL AND FAST PULL DOWN(FPD)

General

Electric capacity control is compulsory in the stand-ard scope of supply for two stage compressors.

Procedure and data

• Refer to diagrams and figures below.

• The possible control steps and the number ofsolenoid valves depends on type of compressor

Standard scope of supply

• One NO-solenoid valve (with LED indicator) forunloaded starting (mounted).

• A number of NC- solenoid valves (each with LEDindicator; mounted).

• Oil pressure lines (mounted).

Options (for two-stage compressors only)

• Fast Pull Down control system

Hint!

FPD is compulsory for R404A andR507.

The standard starting procedure which is con-tained in the standard electrical capacity control,is only suitable if the compressor is being startedat design evaporating temperature.In case the compressor has to start frequentlywith high evaporating temperatures (batch freez-ing, etc), fast pull down capacity control is neces-sary to avoid that the compressor runs continu-ously in part-load.

2.1.5.1 GENERAL DIAGRAM OFELECTRICALLY OPERATEDCAPACITY CONTROL

fig.21

Legend

A Top view of compressor

B Valve lifting mechanism

C Oil return from valve lifting mechanisms to crankcase

D Oil pump

E Electrical wiring, refer Section 2.1.4, page 47

H Supply of oil (control pressure)

NO Normally Open; 3-way solenoid valve for unloadedstarting

NC Normally Closed; 3-way solenoid valve for capacitycontrol



2.1.5.2 DIAGRAMS

Solenoid valve/cylinder numbering for electric capacitycontrol

Com

pres

sor

type 24

HP

cilin

ders

No.

Solenoid

FPD25

NC26

UNL27

NO28

No. 1NC

No. 2NC

No. 3NC

No. 4NC

Cylinder number / solenoid valves

4 - - 1 + 2 3 4 - -

6Singlestage

- - 1 + 3 6 4 5 2

6 Booster - - 2 + 3+ 5 6 4 1 -

9Singlestage

- - 1 + 2+ 3 8 5 + 6 4 + 7

+ 9 -

9Booster

- -1 + 3+ 5 +

82 + 6 4 + 7

+ 9 - -

12Singlestage

- - 1 + 2+ 3 11 5 + 8

4 +10 +12

6 + 7+ 9

12Booster

- -1 + 2+ 3 +4 + 9

5 + 8 6 +11

7 +10 +12

-

31 2 - 2 1 + 3 4 - -

31 + FPD 2 1 2 3 4 - -

42 3 +6 - 3 1 + 2 5 4 + 6 -

42 + FPD 3 +6 6 3 1 + 2 5 4 -

24 Explanation; 2=Grasso 12(E), 21=Grasso 2112(E)25 FPD= Fast Pull-Down26 NC= Normally closed27 UNL= Unloaded starting28 NO= Normally open

Solenoid valve/cylinder numbering for electric capacitycontrol

Com

pres

sor

type 24

HP

cilin

ders

No.

Solenoid

FPD

NC

UNL

NO

No. 1NC

No. 2NC

No. 3NC

No. 4NC

Cylinder number / solenoid valves

51 3 - 3 1 + 2 6 5 4

51 + FPD 3 1 3 2 6 5 4

633 +6 +9

- 3 1 + 2 5 + 8+ 9

4 + 7+ 6 -

63 + FPD3 +6 +9

6 3 1 + 2 5 + 8+ 9 4 + 7 -

72 3 +6 - 3 1 + 2 7 5 + 6

+ 8 4 + 9

72 + FPD 3 +6 6 3 1 + 2 7 5 + 8 4 + 9

84

3 +6 +9 +12

- 3 1 + 2 5 + 7+ 12

8 + 9+ 11

4 + 6+ 10

84 + FPD

3 +6 +9 +12

12 3 1 + 2 5 + 7 8 + 9+ 11

4 + 6+ 10

933 +6 +9

- 3 1 + 5+ 7 8

2 + 4+ 9 +

10

6 +11 +12

93 + FPD3 +6 +9

6 3 1 + 5+ 7 8

2 + 4+ 9 +

10

11 +12

102 3 +6 - 3 + 6 1 + 2

+ 9 4 + 5 10 +12

7 + 8+ 11

102 + FPD 3 +6 9 3 + 6 1 + 2 4 + 5 10 +

127 + 8+ 11



Capacity control steps

Compres-sor type

Capacity %

29 Remarks Cylinders

Solenoids

ϕ30

4single stage& Booster

50 - 1 + 2 - -

75 - 1 + 2 + 3 1 -

100 - 1 + 2 + 3 +4 1 + 2 -

6single stage

33 - 1 + 3 - -

50 - 1 + 3 + 6 1 -

67 - 1 + 3 + 4 +6 1 + 2 -

83 - 1 + 3 + 4 +5 + 6

1 + 2+ 3 -

100 - 1 + 2 + 3 +4 + 5 + 6

1 + 2+ 3 +

4-

6Booster

50 - 2 + 3 + 5 - -

67 - 2 + 3 + 5 +6 1 -

83 - 2 + 3 + 4 +5 + 6 1 + 2 -

100 - 1 + 2 + 3 +4 + 5 + 6

1 + 2+ 3 -

9single stage

33 - 1 + 2 + 3 - -

44 - 1 + 2 + 3 +8 1 -

56 - 1 + 2 + 3 +5 + 6 2 -

67 - 1 + 2 + 3 +5 + 6 + 8 1 + 2 -

78 -1 + 2 + 3 +4 + 7 + 8 +

91 + 3 -

29 Refer to the swept volume expressed as a percentage of thefull-load swept volume for single stage compressors, resp.LP full-load swept volume for two-stage compressors.

30 Number of LP/ Number of HP cylinders


Compres-sor type

Capacity %


Solenoids

ϕ

89 -1 + 2 + 3 +4 + 5 + 6 +

7 + 92 + 3 -

100 -1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9

1 + 2+ 3 -

9Booster

44 - 1 + 3 + 5 +8 - -

67 - 1 + 2 + 3 +5 + 6 + 8 1 -

100 -1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9

1 + 2 -

12single stage

25 - 1 + 2 + 3 - -

33 - 1 + 2 + 3 +11 1 -

42 - 1 + 2 + 3 +5 + 8 2 -

50 - 1 + 2 + 3 +5 + 8 + 11 1 + 2 -

58 -1 + 2 + 3 +

4 + 10 +11 + 12

1 + 3 -

67 -1 + 2 + 3 +4 + 5 + 8 +

10 + 122 + 3 -

75 -1 + 2 + 3 +5 + 6 + 7 +8 + 9 + 11

1 + 2+ 4 -

83 -

1 + 2 + 3 +4 + 6 + 7 +

9 + 10 +11 + 12

1 + 3+ 4 -

92 -

1 + 2 + 3 +4 + 6 + 7 +8 + 9 + 10

+ 12

2 + 3+ 4 -




Compres-sor type

Capacity %


Solenoids

ϕ30

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +

4-

12booster

42 - 1 + 2 + 3 +4 + 9 - -

58 -1 + 2 + 3 +4 + 5 + 8 +

91 -

75 -1 + 2 + 3 +4 + 5 + 6 +8 + 9 + 11

1 + 2 -

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 -

31

0 Starting only 2 - 0.0

67 - 1 + 2 + 3 1 2.0

100 - 1 + 2 + 3 +4 1 + 2 3.0

31 + FPD


33 Starting only 1 + 2 FPD 1.0

67 - 1 + 2 + 3 1 +FPD 2.0

100 - 1 + 2 + 3 +4

1 + 2+

FPD3.0

42


50 - 1 + 2+ 3 1 2.0

75 - 1 + 2 + 3 +5 1 + 2 3.0




Compres-sor type

Capacity %


Solenoids

ϕ

100 - 1 + 2 + 3 +4 + 5 + 6

1 + 2+ 3 2.0

42 + FPD



50 - 1 + 2 + 3 1 2.0

50 Starting only 1 + 2 + 3 +6

1 +FPD 1.0

75 - 1 + 2 + 3 +5 1 + 2 3.0

75 - 1 + 2 + 3 +5 + 6

1 + 2+

FPD1.5

100 - 1 + 2 + 3 +4 + 5 + 6

1 + 2+ 3 +FPD

2.0

51


40 - 1 + 2 + 3 1 2.0

60 - 1 + 2 +3 +6 1 + 2 3.0

80 - 1 + 2 + 3 +5 + 6

1 + 2+ 3 4.0

100 - 1 + 2 + 3 +4 + 5 + 6

1 + 2+ 3 +

45.0

51 + FPD



40 - 1 + 2 + 3 1 +FPD 2.0

60 - 1 + 2 + 3 +6

1 + 2+

FPD3.0

80 - 1 + 2 + 3 +5 + 6

1 + 2+ 3 +FPD

4.0




Compres-sor type

Capacity %


Solenoids

ϕ30

100 - 1 + 2 + 3 +4 + 5 + 6

1 + 2+ 3 +4 +

FPD

5.0

63


33 - 1 + 2 + 3 1 2.0

67 - 1 + 2 + 3 +5 + 8 + 9 1 + 2 2.0

100 -1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9

1 + 2+ 3 2.0

63 + FPD



33 - 1 + 2 + 3 1 2.0


1 +FPD 1.0

67 - 1 + 2 + 3 +5 + 8 + 9 1 + 2 2.0

67 -1 + 2 + 3 +5 + 6 + 8 +

9

1 + 2+

FPD1.3

100 -1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9

1 + 2+ 3 +FPD

2.0

72


29 - 1 + 2 + 3 1 2.0

43 - 1 + 2 + 3 +7 1 + 2 3.0

57 - 1 + 2 + 3 +5 + 6 + 8 1 + 3 2.0




Compres-sor type

Capacity %


Solenoids

ϕ

72 -1 + 2 + 3 +5 + 6 + 7 +

8

1 + 2+ 3 2.5

86 -1 + 2 + 3 +4 + 5 + 6 +

8 + 9

1 + 3+ 4 3.0

100 -1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9

1 + 2+ 3 +

43.5

72 + FPD



29 - 1 + 2 + 3 1 2.0


1 +FPD 1.0

43 - 1 + 2 + 3 +7 1 + 2 3.0

43 - 1 + 2 + 3 +6 + 7

1 + 2+

FPD1.5

57 - 1 + 2 + 3 +5 + 6 + 8

1 + 3+

FPD2.0

72 -1 + 2 + 3 +5 + 6 + 7 +

8

1 + 2+ 3 +FPD

2.5

86 -1 + 2 + 3 +4 + 5 + 6 +

8 + 9

1 + 3+ 4 +FPD

3.0

100 -1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9

1 + 2+ 3 +4 +

FPD

3.5

84


25 - 1 + 2 + 3 1 2.0

50 - 1 + 2 + 3 +5 + 7 + 12 1 + 2 2.0




Compres-sor type

Capacity %


Solenoids

ϕ30

75 -

1 + 2 + 3 +5 + 7 + 8 +

9 + 11 +12

1 + 2+ 3 2.0

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +

42.0

84 + FPD



25 - 1 + 2 + 3 1 2.0


1 +FPD 1.0

50 - 1 + 2 + 3 +5 + 7+ 12

1 + 2+

FPD2.0

75 -

1 + 2 + 3 +5 + 7 + 8 +

9 + 11 +12

1 + 2+ 3 +FPD

2.0

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +4 +

FPD

2.0

93


33 - 1 + 3 + 5 +7 1 3.0

45 - 2 + 3 + 4 +8 + 9 + 10 2 + 3 2.0

56 -1 + 3 + 5 +6 + 7 + 11

+ 121 + 4 2.5




Compres-sor type

Capacity %


Solenoids

ϕ

67 -1 + 2 + 3 +4 + 5 + 7 +

9 + 101 + 3 3.0

78 -1 + 2 + 3 +4 + 5 + 7 +8 + 9 + 10

1 + 2+ 3 3.5

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +

43.0

93 + FPD



33 - 1 + 3 + 5 +7 1 3.0

33 - 1 + 3 + 5 +6 + 7

1 +FPD 1.5

44 - 2 + 3 + 4 +8 + 9 + 10 2 + 3 2.0

56 -1 + 3 + 5 +6 + 7 + 11

+ 12

1 + 4+

FPD2.5

67 -1 + 2 + 3 +4 + 5 + 7 +

9 + 101 + 3 3.0

78 -1 + 2 + 3 +4 + 5 + 7 +8 + 9 + 10

1 + 2+ 3 3.5

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +4 +

FPD

3.0

102

0 Starting only 3 + 6 - 0.0

30 - 1 + 2 + 3 +6 + 9 1 1.5




Compres-sor type

Capacity %


Solenoids

ϕ30

50 -1 + 2 + 3 +6 + 9 + 10

+ 121 + 2 2.5

60 -1 + 2 + 3 +6 + 7 + 8 +

9 + 111 + 4 3.0

70 -

1 + 2 + 3 +4 + 5 + 6 +

9 + 10 +12

1 + 2+ 3 3.5

80 -

1 + 2 + 3 +6 + 7 + 8 +

9 + 10 +11 + 12

1 + 2+ 4 4.0

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +

45.0

102 + FPD

0 Starting only 3 + 6 - 0.0

20 Starting only 1 + 2 + 3 +6 1 1.0

30 - 1 + 2 + 3 +6 + 9

1 +FPD 1.5

40 -1 + 2 + 3 +

6 + 10 +12

1 + 2 2.0

50 -1 + 2 + 3 +6 + 9 + 10

+ 12

1 + 2+

FPD2.5

60 -1 + 2 + 3 +6 + 7 + 8 +

9 + 11

1 + 4+

FPD3.0

70 -

1 + 2 + 3 +4 + 5 + 6 +

9 + 10 +12

1 + 2+ 3 +FPD

3.5




Compres-sor type

Capacity %


Solenoids

ϕ

80 -

1 + 2 + 3 +6 + 7 + 8 +

9 + 10 +11 + 12

1 + 2+ 4 +FPD

4.0

90 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 10+ 11 + 12

1 + 2+ 3 +

44.5

100 -

1 + 2 + 3 +4 + 5 + 6 +7 + 8 + 9 +10 + 11 +

12

1 + 2+ 3 +4 +

FPD

5.0



2.1.6 MANUAL CAPACITY CONTROL

General

Instead of the recommended electric capacity con-trol, a manual operated capacity control system canbe delivered for single stage and booster compres-sors.

Hint!

Electrical supply still required for theNO three-way solenoid valve.Manual capacity control system isequal to standard electric control sys-tem with an extra an oil distributorswitch.Capacity control steps are equal toelectric capacity control.

Procedure and data

• Refer to figure (oil distributor positioned in unloa-ded start).

• Depending on type of compressor one or moreof the distributor ports may not be in use.

• Survey of capacity control steps for each positionof oil distributor handle refer to the relevant tablein this chapter.

• Electrical supply required for three-way solenoidvalve for unloaded starting.


• Three-way NO-solenoid valve for unloaded start-ing (mounted on suction housing, not wired; referto .

• Oil distributor (mounted on suction filter hous-ing).

• Oil pressure lines (mounted).

fig.22: Diagram of manually operated capacity control system

Legend

A Top view of compressor

B Valve lifting mechanism

C Oil return to crankcase

D Oil pump

E Electrical wiring, refer

G Solenoid valve for unloaded starting (NO)

H Supply of oil pressure

J Solenoid valve(s) for capacity control



Legend

NO/NC Normally Open/Normally Closed

ES Manual capacity control switch



Solenoid valve/cylinder numbering for standard capacity control steps

Compressortype

Capacity %

Remarks

Cylinder number

Position of handle of oil distributor

1 2 3 4 5

21250

single stageand booster

2 - - - -

100 - 1-2

312

33


3 - - - -

67 - 1-3 - - -

100 - - 1-2-3 - -

412

50


1-2 - - - -

75 - 1-2-3 - - -

100 - - 1-2-3-4 - -

612

33

single stage

1-3 - 4 5 2

50 - 1-3-6 - - -

67 - - 1-3-4-6 - -

83 - - - 1-3-4-5-6 -

100 - - - - 1-2-3-4-5-6

50

booster

2-3-5 - - - -

67 - 2-3-5-6 - - -

83 - - 2-3-4-5-6 - -

100 - - - 1-2-3-4-5-6 -

912

38

single stage

1-2-3 - - - -

44 - 1-2-3-8 - - -

67 - - 1-2-3-5-6-8 - -

88 - - - 1-2-3-4-5-6-7-8 -

100 - - - - 1-2-3-4-5-6-7-8-9



Solenoid valve/cylinder numbering for standard capacity control steps

Compressortype

Capacity %

Remarks

Cylinder number

Position of handle of oil distributor

1 2 3 4 5

44

booster

1-3-5-8 - - - -

67 - 1-2-3-5-6-8 - - -

100 - - 1-2-3-4-5-6-7-8-9 - -

1212

25

single stage

1-2-3 - - - -

50 - 1-2-3-5-8-11 - - -

67 - - 1-2-3-4-5-7-8--11-12 - -

83 - - - 1-2-3-4-5-6-7-8--9-11 -

100 - - - - 1-2-3-4-5-6-7-8-9-10-11-12

42

booster

1-2-3-4-9 - - -

58 - 1-2-3-4-5-8-9 - -

75 - - 1-2-3-4-5-6-8-9-11 - -

100 - - - 1-2-3-4-5-6-7-8-9-10-11-12 -



2.2 CONTROLS, SAFETIES, GAUGESAND SWITCHES

2.2.1 CONTROLS SINGLE STAGE

In case the compressor will be controlled by a micor-processor-based control device, the pressures, tem-peratures, switches and solenoid valves as men-tioned in the picture below have to be controlled.

fig.23: Controls for single stage compressors

Legend single stage control system

1 Compressor

3 Oil separator

4 Suction pressure header

7 Discharge pressure header

8 Oil pump

9 Oil pressure regulator

10 Solenoid valves for capacity control

11 Capacity control mechanism of the compressor

12 Crankcase oil level switch

13 Cylinderhead temperature sensor

14 Compressor drive motor

16 Solenoid valve oil return protection

19Dependant on type of oil separator:

oil level float switch (19a) or optical oil level switch (19b)

B To capacity control mechanism of the compressor



2.2.2 CONTROLS TWO STAGE

In case the compressor will be controlled by a micro-processor-based control device, the pressures, tem-peratures, switches and solenoid valves as men-tioned in Figure 24, page 60 have to be controled.

fig.24: Controls for two stage compressors


1 Compressor

2 Interstage cooling system

3 Oil separator

4 Suction pressure header

5 LP discharge header

6 HP suction header

7 Discharge pressure header

8 Oil pump

9 Oil pressure regulator

10 Solenoid valves for capacity control

11 Capacity control mechanism of the compressor

12 Crankcase oil level switch

13 Cylinderhead temperature sensor

14 Compressor drive motor

15 Solenoids for interstage cooling system

16 Solenoid valve oil return protection

19 Oil separator oil level switch




B To capacity control mechanism of the compressor

2.2.3 “GSC OP” AND “GSC TP” CON-TROL DEVICE

fig.25: GSC OP (Left), GSC TP (Right)

General

Hint!

The “GSC TP” includes a “TouchPanel” (recommended) while the “GSCOP” includes an “Operating Panel”

The GSC TP/OP consists of the control unit withoperator keypad and display unit, indicator lights for"Running", "Warning" and "Alarm", emergency stopbutton, output relays as well as the housing.The standard version of the GSC TP/OP for Grassopackages with reciprocating compressors is installedseparately next to the package.

The GSC TP/OP performs the following standardfunctions

• Display of all important physical and technicalparameters, e.g. pressure, temperature, motorcurrent, capacity, number of hours run, operatingmode and status signals

• Automatic start up and shut down of the com-pressor unit and capacity regulation dependenton the suction pressure or an external tempera-ture

• Monitoring of all operating parameters

• Compressor capacity limitation, in case the dis-charge pressure, suction pressure, secondaryrefrigerant temperature or motor current limitsare approached

• Alarm memory with date and time

• Wire failure detection for all analogue input sig-nals

• Password protection for preventing unauthorisedaccess to important parameters

• MPI or Modbus RTU communication with a mas-ter controller

• GSC TP (Touch panel)

– 10 Minutes Trend values with display for allactual values, existing directly before alarmshutoff

– Remote access vai Ethernet connection(TCP/IP)

• GSC OP(Operating panel)

– Freeze display with display of all current val-ues just before appearance of the last alarmthat results in the compressor to shut down

Optional functions

• Control of the packege by a master controller,via potential free contacts

• Frequency-controlled compressor drive motor

• Motor current sensor

• Remote setpoint adjustment (analogue signal)

• Profibus DP-communication

• Sequence control (master/slave)



2.2.4 MECHANICAL SAFETYSWITCHES IN ADDITION TOMICRO-PROCESSOR-BASEDCONTROL SYSTEMS

Pressure safety switches NH , Halocarbons and R744

Descriptionof pressure

safetyswitches31

Application

Type

Range ofpressure set-

ting (bar(e))32

Range ofcontact dif-

ferentialpressure

(bar)

Remarks33

StandardEN378-2

TÜV

Sing

le s

tage

Boo

ster

Two

stag

e A

B

Two

stag

e cd

Sing

le s

tage

Boo

ster

Two

stag

e ab

Two

stag

e cd

Number ofswitches 1 1 1 2 2 2 2 4

Low stagedischarge

[Max.]

x x x x RT 30AB 1 .. 10 0.4 fixed

pressure limitor switch,locking device, externalreset, protection class

IP54

x x RT 30AS 1 .. 10 0.4 fixed

pressure safety switch ,locking defice, internalreset, protection class

IP66

High stagedischarge

[Max.]

x x x x x x

RT 6ABor

C4-P808H-S1B-B0-SE34

10 .. 28or

4 .. 170page 62

1.5 fixed

pressure limitor switch,locking device externalreset, protection class

IP54

x x x

RT 6ASor

C4-P808H-S1B-B0-SE-X2

page 62

10 .. 28or

4 .. 170page 62

1.5 fixed

pressure safety switch,locking device, internalreset, protection class

IP66

31 When mounted on a panel all pressure connections of the safety switches are provided with a clamp coupling for ø6 x 1 mm steelprecision tube.

32 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi.33 Protection class of enclosure according to IEC 144 and DIN 40050. Some of the safety switches are provided with a locking device so

that, when cut out, the compressor does not become operative automatically on return of the original pressure. To unlock, an externalor internal reset button is used but only after the reason for cut-out has been investigated.

34 For R744 only.



2.2.5 PRESSURE SAFETY SWITCHPANEL

General

Grasso can deliver a pressure safety switch panel toprotect the compressor.

Selection and Data

• Settings of suction (LP) and discharge (HP)pressure safety switch should be such that themax. pressure difference should never be excee-ded.

• RT260A is used; be aware that a time delayrelay is required.

• Two stage:Wiring of intermediate pressure safety switchshould be such that the contacts are bridgedwhen only HP cylinders are in operation (duringstarting up only).


Pressure safety switches as selected in table below,mounted on a panel.

Hint!

In case the total number of safetyswitches exceeds 5, the safetyswitches will be divided over two sep-arate panels

fig.26: Standard pressure safety switch panel

Legend

A Two stage only

B Crankcase

E Oil

HP High pressure (discharge)

IP Intermediate pressure

LP Low pressure (suction)



Pressure safety switches

Description ofpressure safety

switches35

Application

TypeRange of pres-

sure setting(bar (e))36

Range of con-tact differentialpressure (bar)

Remarks37

OtherEuropeEN378-2

Sing

le s

tage

Boo

ster

Two

stag

e A

B

Two

stag

e C

D

Sing

le s

tage

Boo

ster

Two

stag

e A

B

Two

stag

e C

DNumber ofswitches 3 3 4 5 4 4 5 7

Low stage suc-tion [Min.] x x x x x x x x RT 1A -0.8 to 5 0.5 fixed locking device, external reset, pro-

tection class IP54

Inte

rmed

iate

pres

sure

High stagesuction[Max.]

x x x x RT 5A 4.0 to 17 1.2 to 4.0 without locking device, auto reset,protection class IP66

Low stagedischarge

[Max.]

x x x x RT30AB 1 to 10 0.4 fixed

pressure limitor switch, lockingdevice, external reset, protection

class IP54

x x RT30AS 1 to 10 0.4 fixed

pressure safety switch , lockingdefice, internal reset, protection

class IP66

High stage dis-charge [Max.]

x x x x x x RT6AB 10 to 28 1.5 fixed

pressure limitor switch, lockingdevice external reset, protection

class IP54

x x x RT6AS 10 to 28 1.5 fixed

pressure safety switch, lockingdevice, internal reset, protection

class IP66

Oil differentialpressure [Min.] x x x x x x x x RT

260A 0.5 to 4 0.3 fixed without locking device, without timerelay, protection class IP66

35 When mounted on a panel all pressure connections of the safety switches are provided with a clamp coupling for ø6 x 1 mm steelprecision tube.

36 1 bar = 105 N/m2 = 100 kPa = 1.02 kgf/cm2 = 14.5 psi.37 Protection class of enclosure according to IEC 144 and DIN 40050. Some of the safety switches are provided with a locking device so

that, when cut out, the compressor does not become operative automatically on return of the original pressure. To unlock, an externalor internal reset button is used but only after the reason for cut-out has been investigated.

2.2.5.1 ELECTRICAL WIRING SCHE-MATIC RT260A

General

The oil differential pressure switch should be overrid-den:

i. during starting (to allow the compressor to ach-ieve the required oil pressure)

ii. during normal operation (to avoid nuisancetrips due to system fluctuations

There are 2 methods by which to protect the com-pressor, method A and method B, as describedbelow.



Warning!

If timer 1 (T1) has expired and therequired oil pressure has not beenreached then the compressor must bestopped inmediately

fig.27: Method A, two timers; Recommended wiring diagram, incl. start-up delay timer

Method A

Timers Method A

Timer 1 Timer 1 (T1) for the avoidance of nuisance trips during running. Set time is a maximum of 10 seconds

Timer 2 Timer 2 (T2) for start-up override. Set time is a maximum of 20 seconds and is active once from start-up. Thistimer overrides Timer 1



fig.28: Method B, one timer; Alternative wiring diagram method B, without start-up delay timer

Method B

Timer Method B

Timer 1 By the use of one timer (T1) set at a maximum of 15 seconds for both starting and running.

2.2.6 PRESSURE GAUGES

General

Grasso can deliver a pressure gauge panel.This panel includes stainless steel industrial gauges,diameter 100 mm, connection 1/8” BSP, are glycer-ine filled to reduce the vibration of pointer and pro-tected against overloading.

Selection and Data

• Pressure range suction and intermediate gauge(=also discharge booster):-1 to 12 bar(e).

• Pressure range discharge gauge:-1 to 30 bar(e).

• Pressure range lubricating oil pressure gauge:-1 to 12 bar(e).

• Types of gauges dependant on refrigerant andoperating conditions.

• Number of gauges dependant on single-stage(3) or two-stage (4)

Standard scope of supply single-stage and boos-ter compressors

• 3 gauges (suction, discharge, lubricating oil)

Standard scope of supply two-stage compres-sors

• 4 gauges (suction, discharge, lubricating oil,intermediate)

Options

• Additional oil control pressure gauge:-1 to 30 bar(e)

• Additional connections for pressure sensors:1/4” BSP



fig.29: Pressure gauges and schematic connection diagram

Legend

1

Single stage panelAA=incl. option connection for pressure sen-

sors(1/4”BSP)B=stop valve, TAH4

2 Two stage panel OR single stage panel incl. oil controlpressure gauge

3 Two stage panel incl. oil control pressure gauge

4

Schematic connection diagram(HP Discharge; IP Intermediate; LP Suction; CP crank-case; OdP Oil differential; LO Lubricating oil; CO Con-

trol oil (option); SS Safety switch connections; CCCompressor connections)

2.2.7 THERMO-MASTER

General

The Grasso Thermo-Master offers a complete tem-perature safety to the compressor and is developedespecially for reciprocating compressors operatingunder severe conditions.Each cylinder as well as the oil temperature of thecompressor is monitored.The Thermo-Master consists of a read out module(to be mounted in the electrical control cabinet of theplant), a control box(factory mounted on the baseframe of the package) and temperature sensors(mounted on the compressor).

Hint!

Using this option in combination withan oil cooler, the Thermo-Master con-trols also the oil cooler fan.



Schematic

fig.30: Schematic Thermo-Master

Legend schematic Thermo-Master

RO Read out module, (Rail mounting)

CB Control box

OC Oil cooler (Optional)

CH Crankcase heater

K1, K2 Auxiliary relay (strongly recommended)

TC1 Oil temperature control (Oil cooler fan)

TC2 Oil temperature control (Crankcase heater)

24V/DC Power supply Read Out module

LV Line voltage to RO-potential free contacts TC1 andTC2

Standard functions

a. Discharge temperature monitoring

• Setpoint between 100 oC and 185 oC, onesetpoint for all cylinders. Max. diff. is 30K38

• Number of cylinders; 1 ... 12

• Default setting 155 oC

38 Reset compressor possible when discharge temperatureis 30 K lower as setpoint.

b. Oil temperature monitoring

• Crankcase heater switches off when com-pressor is running or on when compressor isout of operation; Switching on at 40oC,switching off at 45 oC

• If oil cooler is applied, the fan will be control-led when compressor is running; Switchingon at 55 oC, switching off at 50 oC

• Maximum oil temperature is 80 oC. Max. diff.is 20 K39

c. Alarm function

• Each alarm has to be reset manually

• Reset is only possible if the diff. betweensetpoints is achieved.

d. PT1000 Sensors for temperature measurements

e. Dimensions:

• Read out module (LxWxH) approx. 58 x 71 x90 (mm), DIN32 rail mounting

• Dimensions control box (LxWxH) approx.200 x 150 x 76 (mm)

2.2.8 CYLINDER HEAD WATERCOOLING SYSTEM

General

Grasso can supply a cylinder head water coolingsystem which is recommended when operating withNH3 near the discharge temperature limit.

Selection and Data

• Cooling water quantity refer to page 69.

• Maximum water pressure 6.0 bar(e).

• Application of a closed water recirculation sys-tem is recommended.

• Cooling water quality: non-aggresive (not caus-ing corrosion, e.g. sea water or brackish watershould not be used at all).

• Minimum water inlet temperature is condensingtemperature + 10K.

• Stop water flow if compressor is not running.

• Prevent freezing of the cooling water duringstandstill of the compressor at low ambient tem-peratures.

39 Reset compressor possible when oil temperarure is 20 Klower than setpoint.




• Cylinder head covers, internally provided withcooling coil (refer Figure 31, page 69).

• Factory mounted, connections between cylindersby means of rubber hoses (refer Figure 32,page 69).

fig.31: Location of cooling water coil inside cylinder head

Cooling waterinlet temperature

Cooling waterrequired per cylinder

in m3/h (approx.)

Water in/outletconnections

+18 ºC 0.20 2-3-4-6 cyl.compr.: 3/4” BSP

+30 ºC 0.359-12 cyl. compr.:

1/2” BSP+40 ºC 0.80

fig.32: Direction of water flow through cylinder head coolingcoils



2.3 DIRECT AND V-BELT DRIVE

2.3.1 SELECTION OF DIRECT DRIVE

General

Grasso can supply a complete standard direct drive,consisting of a torsional stiff coupling and accesso-ries.

Procedure and data

• Selection: Consult COMSEL.


• Torsional stiff coupling including all parts neces-sary for mounting and securing.

fig.33: Torsional stiff coupling

Legend

ZMZM1

Coupling with flywheel, on compressor side only(ZM and ZM1 are different sizes)

E Coupling Element

M Motor

C Compressor

CF Compressor foot

A Distance compressor foot - motor shaft end

L Distance between coupling halfs

D Diameter coupling (excl. flywheel)

DZM Diameter coupling (incl. flywheel)

2.3.1.1 DIRECT DRIVE OPTIONS

Options

• Drive guard acc. to CE.

• Tool for removing coupling from shaft.

• Tool for alignment

2.3.1.2 COUPLING DIMENSIONS

Dimensions

Coupling type A L D DZM

N80

520(544 for9 and 12cylindermodels)

170

179 -

N90

210

-

N90ZM 345

N90ZM1 320

N115

265

-

N115ZM 394

N115ZM1 338

N135 305 -

2.3.2 SELECTION OF V-BELT DRIVE

General

Grasso can supply a complete V-belt drive system.

Procedure and data

• Selection: Consult COMSEL and

Options

• Flywheel (supplied loose)

• Motor pulley (supplied loose)

• Set of V-belts (supplied loose)

• Drive guard:

® one side protection

® two sides protection acc. to CE (mounted forpackages, else supplied loose)

2.3.2.1 DETAILS V-BELT DRIVE



Flywheel data

Number of grooves40 8 10

Type of Groove SPB

Mass. approx. kg 138 171

Mass moment of inertia kg.m2 10.525 13.8

Dimensions(mm)

D (nom.) 675

a 163 220

b (pitch) 19.0

c 15

d

2-3-4-6 cyl.

9-12 cyl.

117.5 -

141.5 86.5

e

2-3-4-6 cyl.

9-12 cyl.

397.5 -

421.5

40 To determine the required number of V-belts, refer to thegraphs.

fig.34: Flywheel



fig.35: Selection V-belts 50 Hz

Legend

N Standard compressor speed (min-1)

Pe Maximum installed motor power (kW) to transmit

#V Number of V-belts

E Centre distance flywheel - Motor pulley (mm)

L Pitch length of V-belts (mm)

d Diameter motor pulley

grey area

Hint!

for 9- and 12 cylinders only

fig.36: Selection V-belts 60 Hz



2.4 PACKAGED BASE FRAME ANDFOUNDATION BLOCK

2.4.1 PACKAGED BASE FRAME

General

For mounting on a concrete foundation block,Grasso can supply a standard welded steel baseframe to support compressor, motor and accesso-ries.

Especially for vibration free operation on floors andon roof tops, a base frame with vibration damperscan be delivered (concrete foundation block can beomitted).

A. BASE FRAME FOR MOUNTING ON CON-CRETE BLOCK (“TRANSPORT BASE FRAME“)

Design Data

• Base frame to be placed on concrete foundationblock. For foundation block dimensions consultGrasso.

• There should never be a direct rigid connectionwhatsoever between the foundation block andthe floor or any other main part of the building.

• The concrete block should be extended down toany subsoil.

Scope of supply

• Steel base frame, incl mounting of compressor,electric motor and accessories.

B. BASE FRAME FOR MOUNTING ON VIBRA-TION DAMPERS (TORSIONAL STIFF)

Design Data

• Frame to be placed direct on elevated floors andon roof tops (structural floor should be designedto take the weight of the packaged unit).

• Concrete foundation block can be omitted.

• The first two pipe supports must be secured to asolid foundation.

• Horizontal piping must be arranged parallel tothe crankshaft of the compressor.

• Always consult Grasso for installation advice.

Scope of supply

• Steel closed box profile base frame, includingmounting of compressor, electric motor andaccessories.

• Set of vibration dampers.

2.4.1.1 PACKAGED BASE FRAME

fig.37: Packaged base frame, direct drive with oil separator

fig.38: Packaged base frame, V-belt drive with oil separator

Frames on vibration dampers

Hint!

Packaged base frame for mounting onvibration dampers can be determinedby Grasso on request.



2.5 OIL SEPARATOR; OIL RETURNPROTECTION; OIL LEVEL FLOATSWITCH; OIL EQUALISING ANDOIL RETURN

2.5.1 (COMMON) OIL RETURN SYS-TEMS

General

Warning!

Oil return from external sources viasuction line of the compressor isnever allowed.

Be sure for a proper connection of the compressorsuction line. (Refer Figure 39, page 74.)

fig.39: Connections common suction line - suction line com-pressor

Legend (Figure 39, page 74)

1 Preferred connection

2 Allowed connection, but not preferred

3Connection NOT allowed

4

2.5.1.1 EXPLANATION OIL RETURNSCHEMATICS (Sec-tion 2.5.1.2, page 74 andSection 2.5.1.3, page 75)

In the case when one compressor and one oil sepa-rator is applied the arrangement should be in accord-ance with the Schematic Oil Return System I, Sec-tion 2.5.1.2, page 74.The oil from the External Oil Return System (EORS)must be free of refrigerant.If this is not the case then Schematic Oil Return Sys-tem II, Section 2.5.1.3, page 75, must be appliedand an Oil Collecting Vessel (OCV) is obligatory.When more than one compressor is installed with acommon oil separator and in conjunction with anExternal Oil Return System the Oil Collecting Vessel

is obligatory even when the returned oil is free ofrefrigerant.The Oil Collecting Vessel (OCV) must be fitted withOil Temperature Control (TC) to ensure that refriger-ant is evaporated thereby eliminating foaming of theoil returning to the crankcase.In case when an OCV is not applied Oil TemperatureControl (TC) on the oil separator is recommended.

Warning!

When an External Oil Return System(EORS) is applied, oil may only be fedback when the refrigeration plant isclean, normally after 12 months ofoperation; Before returning oil viaEORS, an oil analysys has to be done.

Summarized

1. TC (oil return protection)

1.a Is obligatory in case OCV is applied

1.b Is recommended on the oil separator, incase OCV is not applied and refrigerant isnot R744

2. LCH (oil level control crankcase compressor)

2.a Is obligatory in case EORS is applied

2.b Is obligatory in case of more than one com-pressors on one common oil separator

3. OCV (oil collecting vessel):

3.a is obligatory for one or more compressorsin combination with EORS and returned oilis not free of refrigerant

3.b is obligatory for multiple compressors incombination with EORS, independant if thereturned oil contains refrigerant

3.c is not required for one compressor, withoutEORS

3.d is not required for one compressor, withEORS and returned oil is free of refrigerant

2.5.1.2 SCHEMATIC OIL RETURNSYSTEM I

For explanation of the application of LC, TC andEORS refer Section 2.5.1.1, page 74.



fig.40: Oil return schematic I

Legend oil return system I (refer also Section 2.5.1.1, page 74)

EORSExternal Oil Return System;Oil has to be refrigerant free!

OS Oil separator

EVRA3 Solenoid valve

TAE7 Stop valve

TCOil temperature controller (oil return protection, option).

At low temperature solenoid valve is closed;Recommended if refrigerant is not R744.

C Compressor

LCH

Grasso oil level float switch (optional);At high oil level, solenoid valve is closed;

Obligatory in case EORS is applied.

VC Check valve

H2 Crankcase heater

F Filter (< 50 mu)

2.5.1.3 SCHEMATIC OIL RETURN SYSTEM II

For explanation of the application of LC, TC, EORS and OCV refer Section 2.5.1.1, page 74.



fig.41: Oil return schematic II

Legend oil return system II (refer also Section 2.5.1.1, page 74)

EORS External Oil Return System

OCVOil Collecting Vessel

Obligatory

OS Oil Separator

EVRA3 Solenoid valve

TAE7 Stop valve

TC

Oil temperature controller;At low temperature solenoid valve is closed;

In case OCV is applied, TC is obligatory, otherwise TC on oil separator (oil return protection, option) ;recommended if refrigerant is not R744.

C Compressor

LCH

Grasso oil level float switch (option);At high oil level, solenoid valve is closed;

Obligatory in case EORS is applied OR more than one compressor is connected to one OS.

VCVR

Check valveRegulating check valve

H1 Heater OCV

H2 Crankcase heater

F Filter (< 50 mu)



2.5.2 OIL SEPARATORS SERIES OS(25 BAR)

General

Grasso can supply standard oil separators, designedfor application in discharge lines (also LP dischargelines for interstage cooling system C and D).

Procedure and Data

• Selection:

– Consult Grasso software program COMSEL.


• Oil separator according to CE/PED, DM T/P nr.32974 (French regulations) or GOST-R

• Set of flanges (DIN2635) for inlet and outlet con-nections.

• Float valve assembly, for automatic return of oilto crankcase of the compressor and stop valve(not mounted).

• Oil drain stop valve (not mounted).

• Safety valve connection

Options

• Other approvals on request.

• Base support for mounting on concrete floor.

• Oil return protection.

• Single (1/2” BSP ) safety valve

• Double (1” BSP) safety valve

fig.42: Double safety valve (optional)

Design data

OS3 OS4 OS5 OS6 OS8

Weight(kg) 132 218 305 462 591

Con-tents(dm3)

70 126 227 379 632

Oilcharge(dm3)

6 13 16 22 16

Designpres-sure

(bar(e))

26.0

Testpres-sure

(bar(e))

52.0

Designtem-pera-ture

-10 ... +170 oC

Dimen-sions OS3 OS4 OS5 OS6 OS8

B 97 138 189 240

Refer toFigure 43,page 79,OS8.

D 324 406 508 610

DN-I 50 65 80 100

DN-O 50 65 80 100

E 50 65 80 100

b 190 190 315 315

d 14 14 18 18

l 314 314 439 439

t1 150 150 275 275

t2 270 270 395 395

Li 265 322 477 577

L 1102 1253 1433 1660



Dimen-sions OS3 OS4 OS5 OS6 OS8

H 870 978 1112 1269



OS 3 .. 6 OS 8

H

20

59

15

67

fig.43

Legend

1 Inlet connection

2 Outlet connection

3 Set of flanges

4 Stop valve (type TAH8) for oil return to crankcase (1/2" BSP)

5 Connection for temperature transmitter

6 Float valve

7 Stop valve, oil drain (3/8" BSP)

8 Base support (optional)

9 Dirt drain (3/8" BSP)



Legend

10 Safety valve connection (1” BSP)

2.5.3 OIL RETURN PROTECTION

General

Grasso can supply an oil return protection system, toprevent excessive foaming of oil in crankcase, whichcan occur when starting the compressor after a longperiod of standstill with relatively low oil temperature.(refer also to accessory "crankcase heater")

Selection and Data

• The minimum oil return temperature of the ther-mostat has to be set at approx. > Tc + 5 K and >40 oC.

• Solenoid valve is always closed during compres-sor standstill.

• Sensor to be connected to float valve connectonof oil separator.


• Solenoid valve.41

• Thermostat with sensor(ref. Figure 45,page 80) or PT1000

Options

For packages with built-on oil separator(s):

• Mounting

41 This solenoid valve can also be used in combination withan oil level float switch (refer Section 2.5.4, page 81)

fig.44: Oil return protection

Legend oil return protection

C Compressor

OR Oil return line42

V1 Solenoid valve

TC Thermostat

TT Temperature transmittor

OS Oil separator

fig.45: Thermostat with sensor

Legend (dimensions in mm)

CL Cable length

42 Oil return via the suction line is not allowed!



2.5.4 CRANKCASE OIL LEVELSWITCH

General

In case two or more compressors operate in parallelon one common oil reservoir or oil separator, Grassocan supply an oil level switch.

Selection and Data

• To be fited on crankcase

• Auxiliary relay required (not included)

• Wiring: If "Low oil level" and "Compressor is run-ning" then "solenoid valve open"


• Oil level switch

Options

• Mounting

fig.46: Float switch wiring diagram

Legend

1 Oil level float switch

2 Auxiliary relay (not included)

3 Solenoid valve (not included)

4 Oil return from oil separator or liquid rectifier

N Neutral

L Live



2.5.4.1 CRANKCASE OIL LEVELFLOAT SWITCH

fig.47: Crankcase oil level switch

Leg-end

1 flow switch housing

2 oil level flow switch

3 sight glass (originally on compressor)

2.5.5 OIL RESERVOIR FOR MARINEUSE

Hint!

This option is obligatory for compres-sors installed on board a ship.

Warning!

Using R404A or R507, an externalheater must be mounted around thisreservoir to prevent condensation ofrefrigerant in the oil, in addition of thenormal crankcase heater. This addito-nal external heater is optional.

General

Whenever a compressor is installed on board ship,an adequate supply of crankcase oil to to oil pumpwill be enabled by an oil reservoir.The crankcase of the compressor has an extraflange connection underneath the crankcase, tomount this reservoir.


• Oil reservoir

• Internal suction line oil pump

Options

• Heating element

• Mounting (for packages only)

2.5.5.1 OIL RESERVOIR FORMARINE USE

Hint!

The oil reservoir for marine use isavailable for 4, 6, 9 and 12 cylindercompressors.



fig.48: Location of marine oil reservoir

Legend (all dimensions in mm)

A Oil charge and drain

B Oil drain

C

4 cylinder compressor; 312.5




2.5.5.2 Heating element for oil reser-voir

Heating element is obligatory for R404A an R507,optional for all other refrigerants.Power 300 Watt.

Diameter 168.3 mm.

fig.49

2.6 OIL COOLER

General

Grasso can deliver an air cooled oil cooler.The air cooled oil cooler will decrease the oil temper-ature in the compressor crankcase. The cooler isconnected to the external bypass line of the oilpump. Only when the compressor is in operation, thefan will be started by means of a thermostat43, whenthe oil temperature rises above 55°C and stops whenthe oil temperature drops below 50 °C. The oil tem-perature is measured with an insulated bulb, on theinlet oil line of the oil cooler.

43 In case a Grasso Thermo-Master is applied, the fan iscontrolled by the Grasso Thermo-Master. Refer to Sec-tion 2.2.7, page 67.



fig.50: Oil system including oil cooler

Legend Figure 50, page 84

CLR Air cooled oil cooler, complete

TC Thermostat

M Motor

F Fan

For more details refer to Section 1.5.10, page 45

fig.51: Air cooled oil cooler (refer page 84)

Legend Figure 51, page 84

1 Air cooled oil cooler

2 Oil pump compressor

3 Bulb of thermostat

4 Oil line from oil cooler to crankcase

5 Thermostat

6 Oil line from oil pump to oil cooler

7 Oil cooler support

F Fan (not visible)

Standard scope of supply (refer Figure 51,page 84)

• Air cooled oil cooler (pos. 1), incl. fan and motor(pos. 7)

• Thermostat with bulb (pos. 5)

• Oil lines (pos. 4 and 6)

• For packages; oil cooler support (pos. 7)

Hint!

In case the oil cooler will be suppliedwith a bare shaft compressor, all com-ponents are supplied loose. The piping(pos. 4 and 6) has to be bended onsite.



Technical details

Technical details

Description Value Unit

Type LKI110 -

Cooling agent Air -

Oil charge 2.0 dm3

Test pressure 38.0 bar(a)

Design pressure 26.0 bar(a)

Thermostat RT101 -

Motor power fan 180 Watt

Degree of protection fan motor IP55

Nomimal speed of fan 1.500 min-1

Voltage 1 x 230 V

Frequency 50/60 Hz

Amp. rating 2.5 A

Maximum ambient temperatur 45 oC

Cooling capacity 6.000 Watt

Noise level 64 dB(A)

Dimensions LxWxH 345 x 360x 430 mm

Dry weight, exl. mountingmaterials 18.4 kg

Electrical wiring information

The fan motor has to be wired up (in series) via theRT101 thermostat to the electrical cabinet. Auxiliaryrelay is not required44. Power the oil cooler circuitonly, when the compressor is in operation.

44 In case the Grasso Thermo-Master is applied, an auxiliaryrelay is strongly recommended.

fig.52: Electrical wiring schematic, in case Thermo Master isexcluded.

Legend

K1M Compressor running

TC45 Thermostat, RT101, cut in at 55oC, cut out at 50 oC

M Fan motor

2.6.1 OIL COOLER SELECTIONGRASSO 12E

The oil cooler in compulary for the following condi-tion;

• Grasso 12E series and

• single-stage or two-stage(not for booster) and

• refrigerant NH3 and

• speed >= 1250 min-1.

For all other conditions, the oil cooler is optional.

2.7 CRANKCASE HEATER

Hint!

Recommended for all compressorsand all conditions of operation.

General

During standstill of the compressor, refrigerant maydissolve in the oil charge of the crankcase or it mayeven condense, both due to an increase of crank-case pressure, a decrease of crankcase temperatureand/or possible temperature differences betweencrankcase and evaporator.

Excessive foaming of oil in crankcase, can occurwhen starting the compressor after a long period ofstandstill with relatively low oil temperature which

45 Applied only in case the Thermo Master is EXCLUDED.



may result in damaging the compressor by a lack oflubrication.

Low oil temperatures may also cause a high oil vis-cosity, which may result in troublesome starting.

Selection and Data standard heater

• Refer to table.

• Engine room temperatures below 20 °C.

• Wiring: If "compressor NOT running" then "ele-ment is energised".


• Heater element (mounted, not wired).

fig.53: Standard crankcase heater

Legend

CE Cable entry

RC Removable cap to protect connections

Hint!

Mentioned power in Watt; Standardvoltages are 110-120 V and 220-240 V.

2.7.1 HEATER FITTING DETAIL

Hint!

The standard crankcase heater is fittedinto a sleeve so can be exchangedwhile compressor is in operation.

Number of com-pressor cylin-

ders

Installed power ofheater element

Dimension L(mm)

4 - 6 -9 - 12 525 600

fig.54: Locations of crankcase heaters (Std=standard;Alt=alternavive)

Options

Grasso can supply alternative crankcase heating ele-ments, recommended for low ambient or engineroom temperatures below +15 oC.

Included are:

• Up to 4 alternative crankcase heating elements,600W each (mounted on special service covers).

• Thermostat and sensor PT100, supplied loose.

Not included:

• Auxiliary relais K1 (refer Figure 56, page 87)

Max. number of special cranckcase heaters, each 600 Watt

Number of cylinders Max. number of heating elements

4-6 2

9 3

12 4

fig.55: Alternative crankcase heating element



fig.56: Electrical wiring schematic

Legend

E1, 2, 3 Heater element

XY45 Temperature controlled relay

K1 Relay



2.8 STOP VALVES, FLANGES ANDFILTERS

2.8.1 STOP VALVES, CHECKVALVES AND FLANGES SUC-TION AND DISCHARGE CON-NECTIONS

Hint!

Refer to “Main Dimensions and SpaceRequirements” to determine DN con-nections

General

Grasso can deliver (straight through) stop valves tosuit suction and discharge connections.It is strongly recommend to apply suction and dis-charge stop valves.


• Stop valves (not mounted)

Options

• Additional set of flanges (not mounted)

• Check valves for discharge connections (notmounted)

• Welding stop valves, check valves and matingflanges

2.8.2 STOP VALVE FITTING DETAILS

fig.57: Compressor with stop valve

fig.58: Connections and cylinder numbering



Legend

Single stage and two stage (A and D)Two stage only

Intermediate pressure

A Suction D Discharge B High pressure suction C Low pressure discharge



2.8.3 INTERMEDIATE SUCTION GASFILTER

Hint!

Compulsory for interstage coolingsystem C and D

General

Grasso can supply a suction gas filter which is com-pulsory for HP suction lines of two stage compres-sors interstage cooling system C/D to protect thecompressors.

Selection and Data

• Refer to table.


• filter and mounting materials to fit onto compres-sor (not mounted).

Options

• Additional running-in suction gas filter element.

aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa

fig.59: HP-Suction gas filter

Intermediate filters

DNDimensionms (mm)

compressor typeA B C

50 ø165 375 394 21, 31

80 ø200 404 450 421, 51, 63, 72, 8412E, 93,102

2.9 SPECIAL TOOLS

General

Grasso can supply a set of special tools, for e.g.removal and fittings of pistons, cylinder liners andshaft seal.

Hint!

This set is a must for every engineerwho has to service the compressor.

2.10 HAND-OPERATED OIL PUMP


• hand-operated oil pump

• charging hose

fig.60: Hand-operated oil pump

Leg-end

a Oil charge valve, located on the oil pump ofthe compressor

Warning!

Don’t use the oil drain valve of thecompressor.



2.11 INTERSTAGE COOLING SYS-TEMS

2.11.1 SURVEY OF INTERSTAGECOOLING SYSTEMS FORTWO-STAGE COMPRESSION

General

The criteria for two-stage compression, at certaincombination of condensing temperature tc and evap-orating temperature to, are as follows:

1. Actual discharge temperature too high,

2. Capacity per unit of swept volume too low (poorvolumetric efficiency),

3. Unfavourable specific power consumption.

As a rule of thumb:Two-stage compression becomes necessary whentc-to exceeds 50 K with ammonia or 70 K with halo-carbons, at full load conditions; under partload condi-tions 5 K less.

Survey

One has a choice out of two possibilities: namelybooster operation with LP and HP compressor orcompound operation with LP and HP stage integra-ted in one compressor by means of separate cylindergroups.In principle there is no difference between booster orcompound operation. In both cases gas cooling asclose as possible to saturation point is necessarybetween the LP- and HP-stage. Use is made of thepossibilities in the installation itself, whereby liquidcooling usually takes place between condenser andevaporator.

Different systems of interstage cooling are availablewhereby the advantages and disadvantages of eachsystem determine the field of application. The currentsystems are shown schematically in the figures over-leaf.

fig.61: Survey of Grasso"s interstage cooling systems

a two-stage compressor

b evaporator

c condenser

d oil separator

e throttle control valve for evaporator feeding

f injection interstage gas cooler

g injection interstage liquid cooler

h thermostatic expansion valve

i open flash interstage cooler

j closed flash interstage cooler

k throttle control valve for feeding interstage cooler

LC level control

tc condensing temperature

tm saturation intermediate temperature

to evaporating temperature



Δtm

HP suction superheat

Δto LP suction superheat {Superheat}

Δtvtemperature difference between outlet liquid coil and satu-

ration intermediate temperature tm {DT cooler}

pc absolute condensing pressure

pm absolute intermediate pressure

po absolute evaporating pressure

h enthalpy

Explanation of the operation and comparison ofinterstage cooling systems

System A (Injection interstage gas cooling)

Interstage cooling takes place by injecting liquidrefrigerant from the condenser into an interstage gascooler via an expansion valve. This cooler is moun-ted between the LP discharge and HP suction con-nection of the compressor.

ADVANTAGES:

– Interstage cooling section very simple and inex-pensive; no need for additional isolation stopvalves, oil separator in the LP discharge line orsuction filter in the HP suction line.

– Complete interstage cooling system can be builtonto the compound compressor, thus saving onfloor space in the engine room.

– The installation is conveniently arranged andeasy to control.

– Suitable for all refrigerants

– Reduced oil carry over due to the priority of theliquid supply to the intercooler expansion valve,especially when using ammonia and with thefeed taken from the lowest position of thereceiver, priority vessel (see installation instruc-tions) or HP-float, (take care of dirt), settled oilwill be drained.

Hint!

In case of large plants; exessive oilreturn is possible, safe guard com-pressor against overfilling

DISADVANTAGES:

– Less efficient as the interstage economiser cool-ing system B, C and D.

– Expansion valve operation requires condensingpressure control, to ensure a minimum pressure-difference over the expansion valve(> 4 bar).Too low pressure-differences result in hunting.

– Expansion valve operation requires a minimumload of 25% to obtain stable control. Injectiononly possible in 2-stage mode.

CONCLUSION:

– Application in small to medium-large refrigerationplants, resulting in low costs and simple opera-tion.

System B (Combined interstage gas and econo-miser cooling)

The liquid subcooler is integrated in the gas cooler.The full liquid refrigerant flow is subcooled in a paral-lel circuit inside the interstage cooler.

ADVANTAGES:

– Thermodynamically identical alternative for sys-tem D (see text further on).

– Is characterized by a neglectible refrigerantcharge of the interstage cooler.

– Trouble-free oil return to the HP stage.

– Interstage cooling section smaller, simpler andmore convenient than for system D.

– In principle complete interstage cooling built ontocompound compressor is possible, resulting insaving on floor space in engine room.

– As with system A: no need for additional isolationstop valves, LP oil separator or HP suction filter(direct piping between LP discharge and HP suc-tion).

– Suitable for all refrigerants.

– Less expensive than system D while retainingfavourable capacity and power consumption.

– Reduced oil carry over due to the priority of theliquid supply to the intercooler expansion valve,especially when using ammonia and with thefeed taken from the lowest position of thereceiver, priority vessel (see installation instruc-tions) or HP-float, (take care of dirt), settled oilwill be drained.



Hint!

In case of large plants; exessive oilreturn is possible, safe guard com-pressor against overfilling

– Injection on single stage operation allowed asliquid load of sub cooler ensures stable expan-sion valve operation, resulting in controlled dis-charge temperatures during pull down.

DISADVANTAGES:

– Expansion valve operation requires condensingpressure control, to ensure a minimum pressure-difference over the expansion valve. (>4bar) Toolow pressure-differences result in hunting.

Hint!

On/off control of main user liquid flowshould be prevented. Use base loadvalve open at running compressor,selected on about 70% of minimumcooling capacity at maximum con-densing pressure and a level control-led valve (HP/LP) selected on 120% ofmaximum capacity on lowest condens-ing pressure

Hint!

Do not connect a HP-float after thesubcooler, as this will result in con-densation of high stage vapour in thesubcooler, resulting in large capacitylosses, high intermediate pressuresand high end temperatures.

CONCLUSION:

– Synthesis of the systems A and B, applied insmall and medium-large installations, with theadvantages of system A (simplicity and space-saving) as well as system D (favourable powerconsumption and running costs).

System C (Open flash interstage cooling)

Interstage cooling takes place by passing the full hotdischarge gas flow from the LP stage through a bathof liquid refrigerant inside a interstage cooler vessel,which is aspirated at intermediate pressure by thecompressor HP stage.At the same time, the full liquid refrigerant flow ispassed through this vessel, thereby undergoing adouble- expansion: first from condensing to inter-mediate pressure via a level-controlled throttle valveand then the saturated liquid at intermediate pres-

sure is fed from this vessel to the evaporator via asecond throttle control valve.

ADVANTAGES:

– Enthalpy difference over evaporator has maxi-mum possible value for given operating condi-tions. Therefore, maximum two-stage refrigerat-ing capacity with minimum specific power con-sumption and minimum compressor price perunit of capacity.

– Minimum operating costs assuming a sufficientlylarge number of running-hours per year.

DISADVANTAGES:

– Interstage cooling section rather complicatedand expensive due to the necessity of isolationstop valves, an oil separator in the LP dischargeline and a suction strainer in the HP suction line.

– Requires extra floor space in the engine room.

– (Flash) interstage cooler contains a considerablevolume of liquid refrigerant and traps oil comingfrom the LP-stage.

– Low pressure difference accross the throttle con-trol valve for evaporator feeding.Risk of formingflash gas in liquid line from interstage cooler toevaporator.

– Risk of forming flash gas in liquid line from inter-stage cooler to evaporator.

– Sensitive for intermediate pressure fluctuations

CONCLUSION:

– Optimum system of interstage cooling, withapplication in medium-large to very large ammo-nia installations where the interstage cooler hasbeen fitted approx. level or above the evaporatorand the distance between these components hasbeen kept to a minimum (both installed in engineroom).

System D (Closed flash interstage cooling)

This is a variant of system C. The interstage coolingtakes place in a similar manner, but the liquid refrig-erant flows under condensing pressure via a closedcooling coil in the interstage cooler vessel to thethrottle control valve of the evaporator. So, the liquidexpansion is singular and the level-controlled throttlevalve for feeding the interstage cooler vessel, hasonly to inject just that amount of liquid required forthe interstage gas cooling.At the same time, the full liquid refrigerant flowthrough the coil is subcooled.



ADVANTAGES:

– Alternative for system C, excluding the opera-tional disadvantages. In other words, full pres-sure difference condenser-evaporator availableto properly operate the throttle control valve forevaporator feeding and hardly any risk of flashgas bubbles in liquid line from interstage coolervessel to evaporator.

DISADVANTAGES:

– Refrigerating capacity at given conditions some-what lower than that of system C (approx. 3.5%,due to higher enthalpy of liquid-vapour mixture atevaporator inlet). Therefore, specific power con-sumption and compressor price per unit ofcapacity somewhat higher.

– Interstage cooler slightly more expensive thanthe one of system C due to the built-in coil.

– Total operating costs are somewhat higher thanthose of system C, though still considerably bet-ter than those of system A.

– As system C: more complicated, more expen-sive, takes up more room, necessity of LP oilseparator, HP suction filter and isolation stopvalves between stages.

Hint!

Do not connect a HP-float after thesubcooler, as this will result in con-densation of high stage vapour in thesubcooler, resulting in large capacitylosses, high intermediate pressuresand high end temperatures.

CONCLUSION:

– Application as with system C in medium-large tovery large ammonia installations. Not the opti-mum solution, yet more universal, i.e. withoutrestrictions regarding erection of the differentcomponents in respect of one another.

General remarks A, B, C, D:

• Ensure a continuous condensed liquid supply tothe intercooler expansion valve. Connect theintercooler expansion valve supply-line to alower position than the main-user line(s) other-wise hunting of the expansion valve could occur.

• If no receiver is available (high pressure floatcontrol), use a priority vessel. (For system Aonly: In case of Witt HP-floats, the drain-valve

EA-10-GB under the float-vessel can be used toconnect the intercooler expansion valve supply.)

• Create enough liquid head or subcooling to pre-vent flash gas formation by pressure loss and/orradiation otherwise hunting of the expansionvalve could occur. If the conditions are such thatthis can occur, or in worst case if the intercooleris positioned above the condenser/receiver,Grasso can supply a priority vessel with integra-ted liquid lifting device.

• If subcooling is expected please inform us to pre-vent oversizing of the expansion-valve otherwisehunting of the expansion valve could occur.A built in sight glass before the expansion valvemakes it possible to check if a continuous liquidsupply is secured.

For more detailed layout see general installationinstructions.



2.11.1.1 Graphics interstage coolingsystem A and B

Installation schematic system (Ecotron)A;

fig.62: Installation schematic system (Ecotron)A;

Legend/installation instructions

A Gas cooler

TC Temperature Controller

TT Temperature Transmitter

PT Pressure Transmitter

V1 Stop valve

V2 Solenoid valve

V3

Electronic Expanson Valve(s)

Hint!

In case of GSC; Danfoss AKVA

V4

Thermostatic expansion valve(s)

Hint!

Danfoss TEA

F Filter


S Sight glass

SOS Scope of supply

I Injection Flow

PVPriority Vessel

Gives injection priority to main flow by height (h)

M Liquid to main users

P

Liquid velocity < 0.3 m/s (preferred velocity to allowgas to flow back to condenser)

Diameter Priority Vessel (PV) approx. 3 x diameter ofcondenser connection

Q

Line velocity (m/s)/H(cm/m equivalent line length)=< 0.7 / 20

0.5 / 10=<0.3 / 5

R

Warning!

WRONG! No gas trapsNo liquid-rise, otherwise use Grasso

Priority Vessel (PV)

X

To be opened:System A; 2-stage mode only

System B; 1- and 2-stage mode

Hint!

Single stage injection is required forsystem B to offset the effects of LPsuperheat and the heatload createdby consenser liquid in sub cooler

h Buffer height

H Required static height (refer Q)



Priority Vessel (PV);

fig.63: Priority Vessel (PV);

A B C D E FPV ***

DN (mm) mm

40 32 20 125 15 170 DN40

50 40 25 150 15 170 DN50

65 50 32 200 15 170 DN65

80 65 40 250 20 198 DN80

100 80 50 399 20 198 DN100

LLS = Level Float switch optional on request

Installation schematic system (Ecotron)A;

fig.64: Installation schematic system (ecotron)A

C Liquid from condenser

S Liquid to evaporator

A Subcooler A

1 Stop valve

2 Filter

3 Solenoid valve

4 Sight glass

5 Stop valve

h*

minimum height of float switch in relation to subcoolerA

* Line length max = 30 m

Hint!

NH3; h* > (Qcooler/100)2 (m)



Installation schematic system (Ecotron) B;

fig.65: Installation schematic system (Ecotron) B;


B Gas cooler with integrated subcooler

TC Temperature Controller

TT Temperature Transmitter

PT Pressure Transmitter

V1 Stop valve

V2 Solenoid valve

V3

Electronic Expanson Valve (GSC)

Hint!

Danfoss AKVA

V4

Thermostatic expansion valve

Hint!

Danfoss TEA

V5 Liquid shut off valve (Danfoss EVRAT)


F Filter

S Sight glass

SOS Scope of supply

OPT Optional, on request

I Injection Flow

PVPriority Vessel

Gives injection priority to main flow by height (hp)

M Liquid to main users

MF Main flow

P

Liquid velocity < 0.3 m/s (preferred velocity to allowgas to flow back to condenser)

Diameter Priority Vessel (PV) approx. 3 x diameter ofcondenser connection

Q

Line velocity (m/s)/H(cm/m equivalent line length)=< 0.7 / 20

0.5 / 10=<0.3 / 5

R

Warning!

No gas trapsNo liquid-rise, otherwise use Grasso

Priority Vessel (PV)

XTo be opened:

System A; 2-stage mode onlySystem B; 1- and 2-stage mode

Y

Warning!

Only necessary in case of multiplesubcoolers. Opening pressure loss 0

bar (e.g.Danfoss EVRAT). Must bepositioned on subcooler outlet and

switched off during stand still!

Hp Buffer height priority vessel

H Required static height (refer Q)



Installation schematic system (Ecotron) B (Pre-ferred)

fig.66: Installation schematic system (Ecotron) B (Preferred)

Legend

Installation instruction system (Ecotron) B, insterstagecooler in combination with High Pressure Float Sys-

tem (Equal to system D).

Hint!

PREFFERED BY GRASSO

OPT Optional, on request

M Main users

LS Low stage cylinders

HS High stage cylnders

TC Temperature controller

LC Level controller (Optional, on request)

1Solenoid valve; Base-load valve, to be opened withrunning compressor. Selected on 70% of minimum

cooling capacity at highest Pc

2 Solenoid valve; Level-controlled valve. Selected on120% of maximum cooling capacity at lowest Pc

PV Priority vessel (Optional, on request)

Installation schematic system (Ecotron) B (Notrecommended)

fig.67: System (Ecotron) B, Installation instruction with HP-floats, NOT PREFERRED BY GRASSO!

Legend

Installation instruction (ecotron) sytem B interstagecooler in combination with High Pressure Float Sys-

tems (equal to system D)

Warning!

Not preferred by Grasso!

HPF-N High pressure float, not preferred by Grasso (Consultyour HP-float supplier)

HPF-W

WRONG!High pressure float drains ALL liquid ahead, when fit-

ted lower than subcooler.Integrated subcooler will be overloaded with condens-

ing vapour out of receiver/condenser!

PV Priority vessel (Optional, on request)


HS High stage cylinders


LC Level controller (optional, on request)



Installation schematic Priority Vessel (PV);

fig.68: Grasso Priority Vessel, installation schematic

Legend

MA Main Users, system A

MB Main Users, system B


LC Level controller (optional, on request)

PV

Priority vessel (optional, on request)

Hint!

Grasso’s priority vessel compensatesfor approx. 3 m liquid rise and 30 m

length.


HS High stage cylinders

1 Injection unit, built on interstage cooler

Installation schematic system (Ecotron) B, dou-ble version;

fig.69: Installation schematic system (Ecotron) B, double ver-sion;

Legend

N To be switched off at approx. 50% HP cylinders

HP-S HP-Suction

LP-D LP-Discharge

B Interstage cooler B

MF Main flow

MF-S Subcooled main flow

HP-D HP-Discharge pilot pressure

GPV Gas powered valve

1 Actuator GPV

2 Three-way solenoid valve

2.11.2 INTERSTAGE COOLER (A andB)

General

Grasso can supply two types of interstage injectionsystems:

1. System A, gas cooling.

2. System B, gas and liquid cooling.

Both systems can be supplied with:



1. With electronic expansion valve system.Advantages:

• The software changes the injected refriger-ant flow before compressor capacity step isactivated, thus less sensitive.

• Capacity step time > 60 sec.

• Significant lower stable superheat, 5 to 10 K.

2. TEV, the conventional system with thermostaticexpansion valve(s).Advantages:

• Economical and simple to operateDisadvantages:

• More sensitive to rapid compressor capacitysteps,

• Capacity step time > 180 sec.

• Stable superheat 10 to 15 K.

Procedure and Data

Consult the software program COMSEL.

Standard scope of supply:

Gas cooler and injection unit.



2.11.2.1 MAIN DIMENSIONS ANDSPACE REQUIREMENTSINTERSTAGE SYSTEMS AAND B, GRASSO 12

fig.70

fig.71



2.11.3 OPEN (SYSTEM C ) ANDCLOSED (SYSTEM D) FLASHINTERSTAGE COOLING

General

Grasso’s software program Comsel calculates anopen or closed flash interstage cooling system, sys-tem C, resp. system D. See Figure 73, page 102.System C consists of a vessel only and system Dconsists of a vessel with a built-in subcooling coil.

Procedure and Data

Consult Comsel to determine:

• For system C and D:Di,min = minimum internal diameter in mm (basedon max gas velocity of 0.25 m/s)

• For system D:Capacity of subcooling coil

fig.72: Log p-h diagram

fig.73: Closed “flash” interstage cooling assembly (Open flashwould be without subcooling coil, shown shaded)

a vapour in

b vapour out

c mixture in

d liquid (in/)out

e standpipe

f oil drain

g standpipe

h subcooling coil (system D only)

1 Open or closed "flash" interstage cooler

2 Main standpipe

3 Throttle control valve

4 Oil separator

5 Gas suction filter

A LP-discharge

B Vessel (System C = FTO; System D = FTG)

C HP-suction

D1 Liquid from condenser

D2 Liquid from condenser (System D only)

E (Subcooled) liquid to main users



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GEA Refrigeration Technologies

GEA Refrigeration Netherlands N.V.

Parallelweg 27, 5223 AL ‘s-Hertogenbosch, The NetherlandsPhone: +31 73 [email protected], www.gea.com

GEA Group is a global engineering company with multi-billion euro sales and operations in more than 50 countries. Founded in 1881, the company is one of the largest providers of innovative equipment and process technology. GEA Group is listed in the STOXX® Europe 600 Index.

We live our values.Excellence • Passion • Integrity • Responsibility • GEA-versity

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