PDVSA k-303

PDVSA N TITLE

REV. DATE DESCRIPTION PAG. REV. APPD. APPD.

APPD.BY DATEDATE

VOLUME 9I

1994

K303 LEVEL INSTRUMENTATION

FOR APPROVAL

Eliecer Jimnez Alejandro NewskiAUG. 94 AUG. 94

ENGINEERING SPECIFICATION

AUG. 94 L.T.0 12 E.J. A.N.

ENGINEERING DESIGN MANUAL

ESPECIALISTAS

APPD.BY

REVISION DATE


LEVEL INSTRUMENTATION

Page 1

AUG.940

PDVSA K303

Men Principal Indice manual Indice volumen Indice norma

Index

Page

1 SCOPE 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

2 CODES, STANDARDS AND PRACTICES 3. . . . . . . . . . . . . . . . . . . . .

3 DEFINITIONS 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

4 DESIGN REQUIREMENTS 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.1 D/p cell hydrostatic head 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.2 Buoyancy displacer 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.3 Radio frequency / capacitance / nuclear / ultrasonic 8. . . . . . . . . . . . . . . . . . 4.4 Level switches 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.5 A.P.I storage tank gauging 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.6 Gauge glasses 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7 Solids level measurement / switches 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

5 SPECIFICATION FORMS 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

6 INSTALLATION AND COMMISSIONING 12. . . . . . . . . . . . . . . . . . . . . .

7 Q.A. / Q.C. 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

http://www.intevep.pdv.com/santphttp://www.intevep.pdv.com/santp/mid/indice_mid.htmhttp://www.intevep.pdv.com/santp/mid/vol09-1/indice_vol09-1.htm

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PDVSA K303


FOREWORD

This document is the result of several years work by engineers in the petroleum industryof Venezuela (PDVSA).

The recommendations presented in this publication are not intended to supersedeapplicable laws and regulations.

Users of this recommended practice are reminded that no publication of this type can becomplete, nor, can any written document, be substituted for qualifed engineering analysis.

Suggested revisions are invited and should be submitted to:

The manager

PDVSA Engineering Standards,

C/O INTEVEP TENA Divisin,

Apartado 76343

Caracas 1070A

Venezuela


REVISION DATE


LEVEL INSTRUMENTATIONFLOW INSTRUMENTATION

Page 3

AUG.940

PDVSA K303


1 SCOPEThis section covers PDVSA requirements for the design, specification, installationand commissioning of level instrumentation. All guidelines of the introductionspecification K300 shall also be explicity followed.

2 CODES, STANDARDS AND PRACTICESANSI B31.3 PipingAPI RP550 Instrument InstallationAPI RP551 Process measurement instrumentationAPI 2545 Tank Level GaugingPROCESS INSTRUMENTATION MANIFOLDS JOHN E. HEWSON (ISA)

3 DEFINITIONSAll definitions are listed in the appendix of specification K300.

4 GENERAL REQUIREMENTSLevel measurement to indicate, transmit, record, with or without control facilitiesis classified under the following categories.

Continuous liquid level measurement in process vessels and tanks

They are based on the following principles:

d/p cell hydrostatic head

Buoyancy displacer

Capacitance

Radio frequency / ultrasonic

Nuclear

On off type liquid level switches in process vessels and tanks

Buoyancy float

Capacitance/radio frequency/ultrasonic/nuclear

Gauge glasses

Liquid level measurement in A.P.I. storage tank

Solids level measurement/switches


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AUG.940

PDVSA K303


The following guidelines aid in the design of above items:

Where only a local indication of liquid level other than by means of level gaugeglasses is required and instrument air supply or instrument electricity supply is notavailable, level indicators with magnetic coupling should be considered.

For transmission or local control, displacer level instruments ordifferentialpressure level instruments shall be applied. Differentialpressureinstruments have preference for normal applications.

For special applications, other principles of measurement may be considered,such as ultrasonic instruments or instruments based on capacity, conductivity orradioactivity subject to agreement by PDVSA.

Special provisions such as purging or heating shall be provided to ensure properoperation of level instruments for higly viscous liquids, or for liquids containingsolids, specially if the latter tend to form sediments.

For instruments on highpressure/temperature service due to difference indensity between liquid and vapour to obtain an accurate indication of actual levelunder all operating conditions, consideration shall be given to correct the leveltransmitter output by a computing device using the output of the pressuretransmitter or other suitable means.

On all applications the difference between liquid density and gas/vapour densityshall be taken into account when specifying instruments.

On liquidliquid interface services, especially when the difference in densities issmall, special attention shall be paid to the diameter of the displacer or float toensure measurement accuracy.

Level indicators with magnetic coupling shall not be used on applications wherethe vessel contents is agitated, or where suspended solids in the process liquidsmay deposit on the guide tube.

4.1 D/p Cell Hydrostatic Head4.1.1 The preferred primary element shall be a differential pressure (d/p) cell operating

on the hydrostatic head pressure principle.

4.1.2 All parts in contact with the process fluid shall be 316 stainless steel unless othermaterials are necessary to withstand the fluids corrosive properties. Flanged d/pcells with or without capillary are available as an alternative but attention is drawnto the resulting inaccuracies in measurement.

4.1.3 The d/p cell shall have range elevation / suppression facilities.

4.1.4 On steam drum level measurement reference columns to compensate for errorsdue to differences between water and steam densities shall be installed to ensureaccurate level measurement. See PDVSA drawing No. 3. A copy of this drawingis included at the end of this specification.


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PDVSA K303


4.1.5 Bubbler type and purged systems are a variation of the d/p cell type application.They shall be used on sumps and also on corrosive fluid services. They are idealwhen it is necessary to ensure that the process fluid is not in contact with the d/pcell. (See ISA publication Process instrumentation manifoldsby John E.Hewson, section B for additional details).

4.1.6 Where plugging of the connections is expected, the instruments shall have thehighpressure side of the measuring element exposed, and be suitable for directbolting to a flanged nozzle on the vessel.

4.1.7 Where necessary to avoid plugging of the nozzle, the instrument shall have anextended diaphragm flush with inside of vessel. The extended diaphragm shall,not be specified for instruments on vessels requiring mechanical cleaning. Forinstruments with an extended diaphragm, the diameter of the extension shall becompatible with the inside diameter of nozzle.

4.2 Buoyancy Displacer4.2.1 The buoyancy displacer type complete with external chamber shall be used for

ranges upto 32 inches. Existing displacer installation shall be replaced by d/p cellsat an available opportunity.

4.2.2 Displacers on process fluids operating at more than 200C shall be provided withcooling fins and insulated extensions on fluids operating below 20C.

4.2.3 The external chamber connection size shall be 2. The flange rating shall be 300# minimum unless the vessel connection requires a higher rating.

4.2.4 Instrument materials on cold services require impact testing before and stressrelieving after manufacturing.

4.2.5 Level instruments on LPG storage vessels require a ANSI certificate.

4.2.6 The displacer material shall be stainless steel AISI 316 unless another materialis more suitable.

4.2.7 The external chamber connections shall be located either upper side and bottomor side and side.


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AUG.940

PDVSA K303


CONNECTIONS

VESSEL

4.2.8 All displacer chambers shall be provided with 1/2 N.P.T. valve vent and drainconnections. The connections shall be on the displacer chamber itself or on theinterconnecting pipe. The valves shall be plugged during normal operation.

4.2.9 External displacers shall not be used on fluids that boil or freeze or congeal in thechamber.

4.2.10 Displacer for direct mounting inside process vessels or tanks shall not be used.


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PDVSA K303


4.2.11 A bridle type installation is strongly recommended to mount all the levelinstruments. This type of installation enables all items to be prefabricated andtested for correct functioning in the instrument workshop prior to mounting on thevessel. It also aids in reducing the number of nozzles on the vessel and alsofacilitates subsequent maintenance and readjustments to suit the processconditions without necessity of shutting down the plant.

11

2

GAUGE GLASS

DISPLACEREXTERNAL

2

1

23/4

1

3/4

SWITCHLEVEL

3/4

BRIDLE FOR INSTRUMENTS

d/p CELL


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PDVSA K303


4.3 Radio Frequency / Capacitance / Nuclear / UltrasonicThese types of level measuring instruments shall be used to suit the specificapplication subject to PDVSA approval.

4.4 Level SwitchesThe primary element to indicate the presence of high or low level is based on thefollowing principles:

w. Buoyancy float

x. hydrostatic head

y. Ultrasonic / radio frequency / radar / capacitance

z. Nuclear

4.4.1 The buoyancy type float inside an external chamber complete with a magneticallyactuated hermetically sealed switch shall be used to indicate either high or lowlevel. The external chamber connection size shall be 1 minimum. The flangerating shall be 300# minimum unless the vessel connection requires a higherrating. The chamber connections shall facilitate testing switch action easily.

VESSEL CONNECTIONS


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PDVSA K303


4.4.2 The float material shall be 316 stainless steel and the chambers shall be forgedcarbon steel unless other materials are necessary to resist the fluids corrosionproperties.

4.4.3 The level switch shall be snap acting D.P.D.T. type and wired to a block with three(3) terminals so that either a normally closed (NC) or a normally open (NO) actioncan be chosen to meet the necessary electrical circuitry requirements.

The switch shall be snap acting, hermetically sealed, tropicalised and corrosionresistant to marine and any other specified toxic ambience. The switch rating shallbe 1 amp at 24 volts D.C. Mercury type switches shall not be used.

4.4.4 Floats without external chambers for direct mounting inside vessels, tanks orsumps shall not be used.

As an alternative a continous level measurement transmitter which operates aseparate trip switch is the PDVSA recommended practice. When these switchesform part of a protection circuit, the primary level transmitter shall be independentof any other level measuring system installed on the same vessel / tank / sump.

4.4.5 Level switches shall only be used where:

Instrument air supply is not available, e.g. in tank farms The simplicity of the application does not justify a transmitter, e.g. on lube

oil/seal oil tanks for running equipment.

4.4.6 All other types of level switches such as ultrasonic / nuclear / radar / capacitanceshall be used to suit the application and subject to PDVSA approval.

4.5 A.P.I Storage Tank GaugingAll tank gauging systems shall have remote read out on the main panel in thecontrol room.

Tank gauging for custody transfer shall be radar or servo motor operated(surface seeking) type, with remote checking facilities.

The level measuring systems on tanks on custody transfer service shall have ameasurement accuracy of 1 mm. The accuracy shall be certified by arecognised authorityDIN, etc...

Corrosion resistant materials shall be used throughout.

Where storage tanks require an averaging temperature detector, this shall formpart of, and be connected into, the tank gauging system. These averagetemperature detectors shall be fixed multiple resistance elements, Pt100 type.

Where a spot reading temperature detector is required this shall be provided in thelower part of the tank and shall be a resistance thermometer connected to atemperature indicator.


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PDVSA K303


4.6 Gauge GlassesThe following are the types of gauge assemblies directly connected to the processvessel.

a. Reflex glass column

b. Transparent (thruvision) glass column

c. Metal tube with magnetic follower

d. Metal tube with conductance electrodes

4.6.1 Gauge glass columns shall be provided on all process vessels installedimmediately adjacent to any additional level instrumenttransmitter, indicator orswitch. They shall not be installed on silos or A.P.I. storage tanks.

4.6.2 Thruvision (transparent) type gauge glass shall be specified on the followingapplications:

a. Interface between two liquids

b. Coloured liquids with specific gravity 0,9 or higher

c. Liquids containing gum, sediment or other solid particles which cling to theglass

d. Boiler feed water services

e. Glasses requiring mica shields

f. Liquids not easily visible or tend to be opaque

On all other services reflex type gauges glass columns shall be used.

On corrosive and toxic services, fluids operating at more than 60C, and oncryogenic services the metal tube with magnetic follower type of gauges shall beused. Another available alternative is the metal tube with electrodes subject to thefluid conductance properties.

4.6.3 Level gauges need continuous maintenance to ensure good and clear levelvisibility. Hence consideration shall be given in providing only valved connectionson a vessel to which a gauge can be connected for e.g. during startup, levelinstrument / switch calibration, etc.

4.6.4 A sufficient number of gauge glass columns shall be provided so that the visiblelengths provide complete coverage of the allowable range of liquid level inside thevessel.

4.6.5 Gauge glass columns shall consist of one or more gauge glass sections with thenecessary isolating valves to permit cleaning of the glass. There shall not be morethan three (3) sections in each gauge glass column. Each section shall have 12inches (300 mms) visible length.


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AUG.940

PDVSA K303


4.6.6 When two or more gauge glass columns are required to cover a level measuringrange the visible portion of the gauges shall overlap atleast 1 inch (25 mms).

4.6.7 Gauge glasses on steam boiler units (Drum, deaerator, etc.,) shall conform withASME section I requirements.

4.6.8 Each gauge column shall be complete with its own individual isolating valvescomplete with a ball check device to shut off flow in the event of glass breakage.

4.6.9 Bridle assemblies are strongly recommended in order to reduce the number ofnozzles on vessels to mount gauge glass columns and associated levelinstruments. See paragraph 4.2.7.

4.6.10 Length of nipple between glass sections or glass and isolating valve shall notexceed three (3) inches.

4.6.11 Gauge glass columns shall be provided with a 1/2 N.P.T. drain valve plugged anda 1/2 N.P.T. plugged vent.

4.6.12 The liquid chamber and cover plate shall be forged steel unless other material isnecessary to withstand the fluids corrosive properties. The inside of the chambershall have a nonremovable black finish.

4.6.13 Gauge glass quality shall be shatterproof so that in the event of breakage thereare no loose or flying glass particles. All glasses shall be armoured type. Tubulargauge glass shall not be used.

4.6.14 Gauge glass columns on boiler feed water, caustic and other fluids that attackglass shall be provided with mica shields to protect against glass etching.

4.6.15 Gauge glass columns operating on process fluids below 0C shall be providedwith frost shields.

4.6.16 Gauge glass shall be heat traced on all process fluids that freeze or congeal inaccordance with A.P.I. R.P.550, section BSeals, purges and winterizing.

4.6.17 Gauge glass lighting shall only be provided subject to PDVSA approval fortransparent type glasses if the gauge glass column is not conveniently accessiblefor backside illumination and simultaneous observation by an operator with ahand held light. The electrical items shall conform to the area electricalclassification. The lighting and gauge glass column shall be procured as onecomplete assembly.

4.7 Solids Level Measurement / SwitchesFor continuous level measurement and/or high/low level indications of solidsinside vessels, silos, etc. the primary element selected shall have provenoperational reliability based on any of the principles listed below:


REVISION DATE



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AUG.940

PDVSA K303


a. Float

b. Capacitance

c. Radar / ultrasonic

d. Nuclear

The selected item shall be subject to PDVSA approval.

5 SPECIFICATION FORMS

FORM No. TITLE

20.1a and 1b Receiver instruments

20.10a and 10b Single/Multiple input Millivolt/Milliamp instrument

20.20a and 20b Differential pressure instrument

20.26 Displacer level instrument

20.27 Capacitance level instrument

20.28 Gauge glasses

The forms are included at the end of this specification.

6 INSTALLATION AND COMMISSIONINGAll installation and commissioning shall be performed in accordance with projectdrawings and specifications.

7 Q.A. / Q.C.All items shall conform with the procedures detailed in specification K369.


RECEIVER INSTRUMENTS

Item N Tag. N No. ofinputs

Notes:

20.1b

ScaleRanges

Service

PROJECT REFERENCEITEM N QUANTITY

SPECIFICATION REFERENCES I.S.A SPDVSAK

N By REVISED DATE

OFF SHEET OF

ChartRanges

REVISION DATE


INSTRUCTIONS TO FILL FORMS20.1A AND 20.1B

Page 1

AUG.940

PDVSA 20.1


RECEIVER INSTRUMENTS

a. To be used for a single item. Use secondary sheet for multiple listing.

b. Check as many as apply.

c. Nominal size refers to approximate front of case dimensions; width x height.

d. It is assumed that the instrument has its own case of shelf suitable for singlemounting, unless MULTICASE is checked. Shelf or separable case for multiplecase mounting instrument is not included unless listed and described as anaccessory.

e. Enclosure class refers to composite instrument. If electrical contacts are the casethey must meet this classification inherently or by reason of the enclosure. UseNEMA identification system or ISA System RP8.1.

f. Specify electrical power to the entire instrument from an external source.

g. For multiple instruments list ranges on secondary sheet, but specify other chartoptions on primary sheet. Chart graduations assumed to be uniform unlessotherwise noted. Circular charts assumed to have 24 hr/revolutions speed; stripcharts 3/4 in. to 1 in. per hour.

h. Chart drive mechanism assumed to be synchronous motor operating on 117V 60Hz and suitable for ENCLOSURE CLASS specified on line 5. If the chart drive ispneumatic so state identify pneumatic pulser under options. Notes deviationsfrom standard (MFR) under notes i.e., dual speed or special speeds.

i. The scale type may be SEGMENTAL, VERTICAL, HORIZONTAL, DIAL(CIRCULAR) or other. Ranges 1, 2, 3 and 4 are used for multiple inputs. The firstlisted (N 1) is assumed to be the controller input, if a controller is used.

j. See explanation of terminology given on specification sheet. For further definitionrefer to American National Standard C85.11963, Terminology for AutomaticControl. Specific ranges of control modes can be listed afetr OTHER, ifrequired.

k. For multiple items specify on second sheet.

l. If standard automanual switching is not known or not adequate, specify particularrequeriments, such a BUMPLESS, PROCEDURELESS, 4POSITION, or asrequired.

m. Remote set point adjustment assumes full adjustment range. Specify limits ifrequired. Under other can be noted bias or ratio.

n. Specify if applicable.

o. Specify if applicable.


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AUG.940

PDVSA 20.1


p. All input signals on multichannel instruments assumed to be the same unlessotherwise noted.

q. Specify number of inputs.

r. Check if power source for the loop is contained in this instrument or in someexternal instrument.

s. Form may be SPST, DPDT or other. Rating refers to electrical rating of switch orcontacts in amps.

t. Specify if alarm is actuated by measured variable or by deviation from controllerset point, Give contact action if single throw form.

u. Specify required accessories and options, fill in number of charts. This is assuredto be number of chart roles for strip charts.

v. After selection is made fill in manufacturer and specific model number.

SECONDARY SHEET For listing multiple instruments. List all instruments of thesame type specified on the primary sheet, with variations an shown. Notes refersto notes listed by number at the bottom of the sheet. Line 11 of sheet 1a istabulated under measurement increases, output tabulate increase or decrease.


SINGLE/MULTIPLE INPUT MILLIVOLT/MILLIAMP INSTRUMENT

GENERAL

Notes: 1. All weatherproof and explosion items shall be corrosion resistant to marine atmosphere and tropicalised.2. Alarm contact shall be normally closed and open on alarm condition. Alarm setting shall be programmable.3. Programmable

CONTROLLER

20.10a

XMTR/TRANSD.

Record Indicate Control Transducer

1. Tag N Service

2. Function

4. Mounting Flush Surface Other

3. Input Thermocouple ref. junction comp. J (IC)

Resistance bulb 3wire 4wire Calibration:

110 V 60 Hz 24 Volts D.C.



N By REVISED DATE

OFF SHEET OF

6. Power Supply

7. Chart Roll Fold Circular Range Speed: See Note 3

10. Output 420 mA 315 psig Other

inputoutput isolation

11. Control Modes P PI Other Reversible Action

Automan Switch Manual Reg Manual loading STN.

12. Set Point Adj. Manual Remote

13. Output 21103 kPa (315 psig)420 mA

15. Input open circuit

14. Switches Function on measurement input High Low High and Low

Rating 1 AMP. at 24 Volts D.C. see note 2No. of alarms

MFR 16. Model N

DownscaleUpscale Charts

Milliamps

PID

ALARMS

Single input Multiple inputs No. of inputs

K (CA) T(CC) Other

420 m.A. Power supplyThis inst. Ext.

Frequency/pulse Power supplyThis inst. Ext.

Safe area Classified Class Group Div

Weatherproof Ex. Proof Intr. safe STD.

Temp. Class T1 T2 T3 T4 T5 T6

5. Enclosure

8. Scale Range Direct Readout Multiple ranges Single

9. For multiple inputs Selector switches per note 3 Scan speed Seconds per point.

For receiver see sheet

Int. IllOPTION

SINGLE/MULTIPLE INPUT MILLIVOLT/MILLIAMP INSTRUMENT

Item N Tag. N Scale and Chart Range

Notes:

Individual

20.10b

Point No. Input typeService



N By REVISED DATE

OFF SHEET OF

REVISION DATE



Page 1

AUG.940

PDVSA 20.10


MILLOVOLT OR MILLIAMP INSTRUMENT SPECIFICATION SHEET INSTRUCTIONS

Prefix number designates line number on corresponding specification sheet.

1. To be used for single item. Use secondary sheet for multiple listing.

2. Check as many as apply.

3. Check one. Note that sheet may be used to specify galvanometric type ofinstrument.

4. Nominal size refers to approximate front of case dimensions: width x height.

5. It is assumed that the instrument has its own case or shelf suitable for singlemounting unless multicase is checked. Shelf or separable case for multiplecase mounting instrument is not included in this sheet unless listed as anaccesory.

6. Enclosure Class refers to composite instrument. If electrical contacts are in thecase, they meet this rating inherently or by reason of the enclosure. Use NEMAidentification system or ISA system presented in RP8.1.

7. Specify electrical power to entire instrument.

8. For multiple instrument list ranges on second sheet, but specify other itemshere.

9. Ranges 1 and 2 refer to multichannel instruments. The first listed is assumedto be the controller input (if any).

10. For multiple items list number of point on second sheet. Point Select permitsbypassing any or all points by a switching mechanism.

11. For multiple items show number of switches on second sheet under No. ofPoint.

12. Specify if applicable.

13. See explanation of terminology given on spec. sheet. Specific ranges of controlmodes can be listed under other if required.

14. For multiple items specify on second sheet.

15. If standard automanual swithching is not known or not adequate, specifyparticular requirements, such as BUMPLESS, PROCEDURELESS,4POSITION, or as required.

16. Remote set point adjustement assumes full adjustment range. Specify limitsif required.



19. Check if thermocouple input applies. Lead resistance required only forgalvanometer.


REVISION DATE



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AUG.940

PDVSA 20.10


20. Specify any input other than thermocouple. Calibration refers to curve usedand does not imply that element is specifically calibrated for this instrument.

21. Form may be SPST, SPDT, DPDT, etc. Rating is electrical rating of switch inamps.

22. Check if alarm is actuated by measured variable or by deviation from controllerset point. Give contact action if single throw form. Specify calibrated or blindalarm index setter.



25. Accesories for multiple items may be covered by notes second sheet.

26. May be filled in after selection is made.

SECONDARY SHEET for listing multiple instruments. List all instruments of thesame type, specified on Primary Sheet, with variations as shown. Notes refersto notes listed by number at the bottom of the sheet. Or use secondary Sheet tolist and identify the multiple points of a single multipoint instrument.


DIFFERENTIAL PRESSURE INSTRUMENTS

Notes: 1. All items shall be corrosion resistant to marine atmosphere and tropicalised.2. Alarm contact shall be normally closed and open on alarm condition. Alarm setting shall be adjustable

20.20a


3. Material

5. Power Supply





N By REVISED DATE

OFF SHEET OF

GENERALRecord Indicate Control Transm

1. Tag N Service2. Function

110 V 60 Hz 24 Volts d.c.

XMTR 9. Output 420 m.A. 315 Psig Other

Conn1/2 nptRating18. Body

23. Model No

CONTR

ALARMS

OPTIONS

MFR

Integrator

Yoke

4. Enclosure

10. Cont. Mode P PI Reversible Action

Diaphragm Bellows16. Element

Body Element17. Material

Flanged

SERVICE

19. Diff Range Adj. Range Set At

Other

20 Psig

6. Chart Circular Range DriveElec Spring Speed

8. Scale Range 1 2 3

12. Set Point ADJ Manual Remote

13. Output 420 m.A. 315 Psig Other

Flow Level Diff. Press Elevation14. Type Suppression

Fluid Max. Temp.Max. Press20. Process Data

22. Options Pressure element Range Material

Temp. Element Range Type

Filt Reg Gauges Charts 3valve manifold

Function on measurement input High Low High and Low

Rating 1 AMP. at 24 Volts D.C. see note 2No. of alarms

21. Switches

20.20b




N By REVISED DATE

OFF SHEET OF

Tag. N

NOTES

Set Range ServiceScale or Chart NotesScale Factor

REVISION DATE



Page 1

AUG.940

PDVSA 20.20a



1. To be used for a single item. Use secondary sheet for multiple listing.

2. Check as many as apply.

3. Nominal size refers to approximate front of case dimensions; width x height.

4. Yoke refers to a bracket designed for mounting the instrument on a pipe stand.

5. Enclousure class refers to composite instrument. If electrical contacts are thecase they must meet this classification inherently or by reason of theenclousure. Use NEMA identification system or ISA System RP8.1.

6. Specify electrical power to the entire instrument from an external source.

7. Specify chart size, range and number if applicable.

8. 24 hr is the time for one rotation of the chart. Other speeds should be listedin hours or days. If a spring wound clock is used fill in number of hours or daysit runs between windings.

9. The scale type may be SEGMENTAL, ELECTRIC, or DIAL (CIRCULAR).Space is provided for multiple ranges on the same scale.

10. Specify transmitter output if applicable.

11. See explanation of terminology given on specification sheet. For furtherdefinition refer to American National Standard C8511963, Terminology forAutomatic Control. Specific ranges of control modes can be listed afterOTHER, if required.

12. For multiple items specify on seconds sheet.

13. If standard automanual switching is not known or not adequate, specifynumber of positions.

14. Remote set point adjustment assumes full adjustment range. Specify limits ifrequired.



17. Specify measured variable.

18. Specify type od element or write in MFR.STD.

19. Materials refer to wetted parts only.

20. Overrange protection refers to maximum differential pressure. Theinstrument can withstand without a shift in calibration.

21. Adjustable range means that the range can be changed without replacing anyparts.

22. Elevation.


REVISION DATE

Page 2

PDVSA


23. Give process data affecting meter selection. Flow elements such as orificeplates are specified on separate forms.

24. Refers to connections piped to process equipment or pipe line. Special flangedconnections and extended diaphragms for level applications should bedescribed afetr OTHER.

25. Form may, be SPST, DPDT, or others. Rating refers to electrical rating of switchor contacts in amps.

26. Specify if alarm is actuated by measured variable or by deviation from controllerset point. Give contact action if single throw form.

27. Specify required accessories. If temperature element is used, the second lineis provided to specify well, length of capillary tubing and other details of thethermal system.

28. After selection is made fill in manufacturer and specific model number.

SECONDARY SHEET For listing multiple instruments. List all instruments of thesame type specified on the primary sheet, with variations an shown. Notes refersto notes listed by number at the bottom of the sheet.


LEVEL INSTRUMENTS (DISPLACER OR FLOAT)

Notes: 1. All items shall be corrosion resistant to marine atmosphere and tropicalised.

20.26

Safe area

Size

Classified Class Group Div

5. Lower Conn.

3. Material

8. Power Supply

Location




SPECIFICATION REFERENCES I.S.A SPDVSAK301

N By REVISED DATE

OFF SHEET OF

GENERALTrans Contr Trans & Contr Level switch

1. Tag N Service

2. Function

4. Upper Conn.

24 Volts d.c. Ext. 20 Psig

XMTR

10. Length

18. Switches Contacts to On Rise

12. Ouput 420 m.A. 315 Psig Other

Max. Temp.Max. Press16. Conds.

19. Model No

CONT

BODY/CAGE

ALARMS

OPTIONS

MFR

SP.GR Compensation

Rating

Size Location

7. Enclosure

8. Power Supply 24 Volts d.c. Ext. 20 Psig

9. Extension Cooling Radiation

11. Material Displacer Torque Tube

13. Cont. Mode P PI Reversible Action

Upper SP.GR14. Liquid

Lower SP.GR15. Liquid

Min. Temp.

On Fall In level

Rating 1 Amp at 24 volts d.c.

AND CASE

DISPLACEROR FLOAT

PROCESS

17. Options Filter Reg Supply/Ouput Gauges

REVISION DATE


INSTRUCTIONS TO FILL FORM 20.26

Page 1

AUG.940

PDVSA 20.26


LEVEL INSTRUMENTS (DISLACER OR FLOAT)

1. Tag N or other identification.2. Process service.

3. Line number or vessel number on which cage or body is installed.

4. Material of chamber and/or mounting flange.

5. For float specify top or side of vessel connection. For displacer in a chamberspecify upper, then lower connection; such as sideside, sidebottom, etc.Give flange size and rating or NPT size.

6. Same as 5.

7. Refers to position of case when viewing the front of the case relative to thechamber; the case is either to the left, right, or top.

8. On displacer instruments specify if case is to be rotatable with respect to thechamber. This only applies if there is one or more side connections.

9. Orientation of control with respect to displacer cage.

10. Cooling Extension.

11. Specify float diameter or displacer length. The displacer length is also therange.

12. Insertion depth applied to ball floats. It is the mounting flange to the center ofthe ball.

13. The displacer extension is measured from the face of the mounting flange tothe top of the displacer. This dimension is required only for top of vesselmounted instruments.

14. Includes rod.

15. Refer to MFRs standard materials or special materials.

16. Transmitter, controller, switch, etc.

17. Air pressure or electrical signal output of transmitter or controller.

18. P: Proportional.

Pn: Narrow band proportional

PI: Proportional plus Integral (Reset).

19. Differential if controller on/off must specify differential adj. or fixed. Stateadjustable range or fixed amount.

20. INCREASE (Direct action) or DECRESE (Reverse action).

21. Remote, or integral.


REVISION DATE



Page 2

AUG.940

PDVSA 20.26


22. Electrical classification of housing. NEMA number.

23. Air pressure or voltage. If electronic, state whether ac or dc.

24. Used only for interface application.

25. Used for all services.

26. Specific gravities at operating temperature.

27. Operating and max. pressure, or vacuum.

28. For cryogenic service, give minimum temperature.

29. Airset assumed mounted to case.

30. Connections on chamber, give size.

31. Specify gauge glass, if required.

32. Contact form: SPST, SPDT, etc.

33. Give Volts, Amps.

34. Describe contact action with level.

35. Model number of entire assembly.


LEVEL INSTRUMENTS (CAPACITANCE TYPE)

Notes: 1. All items shall be corrosion resistant to marine atmosphere and tropicalised

20.27


5. FailSafe

3. Application

8. Style





N By REVISED DATE

OFF SHEET OF

GENERAL 1. Tag N Service

4. Function

10. Sheath

18. Conduit Connections

12. Inactive Length

19. Power Supply

AMPLIFIER

SWITCH

MFR

2. Enclosure

9. Material

11. Insertion Length

13. Gland Size & Matl

14.

15. Conduit Connection

PROBE

17. Enclosure

6. Model Number

7. Orientation

16. Location

20. Type

22. Rating: Volts/Hz or dc

21. Quantity and Form

23. Amps/Watts/HP

24. Load Type

25. Contacts

26.

OpenClose

OnLevel

Incr.Decr.

Model No

TRANS.

OPTIONS

SERVICE

27. Output

35. Upper Fluid

29. Enclosure Class

36. Dielectric Constant

28. Range

30. Compensation Cable

31. Local Indicator

32. I.P Transducer

34.

33. Signal Lights

37. Lower Fluid

39. Pressure Max.

38. Dielectric Constant

40. Temp. Max.

41. Moisture

42. Material Buildup

43. Vibration

Normal

Normal

REVISION DATE



Page 1

AUG.940

PDVSA 20.27


LEVEL INSTRUMENTS, CAPACITANCE TYPE

Prefix number designates line number on corresponding Specification Sheet.

1. Identification of item by tag number.

2. Process area or function.

3. Stream description and/or pipe size and number or vessel number in whichprobe is installed.

4. Specify solids level, liquid level, interface, foam detection, etc.

5. Specify alarm, transmit, onoff control, etc.

6. Specify high, low, none.

7. Specify probe model number if known.

8. Specify if probe axis is horizontal, vertical, etc.

9. Specify general purpose, heavy duty, knifeblade, inline plate, concentricshield, etc.

10. Specify probe material as 316 SS, etc.

11. Specify sheath, required, as 1/4 in. Teflon, etc.

12. Specify total inmersion in inches, or feet and inches.

13. Specify length of inactive extension in inches, or feet and inches.

14. Specify sealing gland material and size as 316 SS, 3/4 in. NPT, etc.

15. Specify conduit connection as 3/4 in. NPT hub, 7/8 in. OD knockout, etc.

16. Specify if electronics are mounted at probe or remotely located.

17. Specify general purpose, weather proof, explosion proof, etc.

18. Specify conduit connection as 3/4 in. NPT, 7/8 in. OD knockout, etc.

19. Specify power input as 115 V 60 Hz, etc.

20. Specify switch type as mercury bottle, snapaction, etc.

21. Specify number of switches and contact form of each switch (SPST, SPDT,DPDT, etc).

22. Specify switch voltage as 115 V 60 Hz, 24 Vdc, etc.

23. Specify contact rating in amps, watts, or horsepower.

24. Specify load as inductive on noninductive.

25. Specify if contacts open or close when the level increases or decreases.

26. Specify transmitter output as 15, 420, or 1050 mA, 15 Vdc, etc.


REVISION DATE



Page 2

AUG.940

PDVSA 20.27


27. Specify level range in inches or feet and inches corresponding to minimum andmaximum transmitter signal.

28. Use NEMA identification mumbers.

29. Specify length of special compensating cable to be furnished with probe, ifrequired.

30. Specify size, type and range of local indicator, if required.

31. Specify if electropneumatic transducer 21303 kPa (315 psig output) isrequired.

32. Specify if High, Low, HI/LO lights are required, and rating.

33. For items not covered in lines 31 through 34.

34. Specify upper fluid by name and state (liquid, vapor).

35. Specify dielectric constant of upper fluid.

36. Specify lower fluid by name and state.

37. Specify dielectric constant of lower fluid.

38. Specify maximum and normal operating pressure at probe.

39. Specify maximum and normal operating temperature at probe.

40. Specify percentage moisture content of solids.

41. Specify if material is expected to buil up on probe.

42. Specify vibration environment of probe as mild, severe, etc.

43. Fill in manufacturer and model number after selected.


GAGE GLASSES AND COCKS

ItemN

Quan. Tag N VisibleGlass Press. Temp

.

Service

Notes:

1. All items shall be corrosion resistant to marine atmosphere

Conn.

20.28

Model NOperating



N By REVISED DATE

OFF SHEET OF

Ext. Length

1. Gage Column Cocks Assembled with Nipples

2. Type:

3. Conn:

Vent

9. Conn:GAGE GLASSES

Reflex Transparent Tubular

Size and Type

4. Material

5. Min. Rating psig at F

6. Options: Illuminator

NonFrostCalb. Scale

Internal Tube

7. Manufacturer & Model

8. Type: Offset Straight

Other:

Large Chamber Weld Pad

Top & Bot. Side Back

Drain

Mica ShieldExternal Jkt

Other

Vessel Gage Vent/Drain

10. Material: Body Trim

11. Min. Rating: psigat

F

12. Construction: Vessel

Gage13. Bonnet

15. Options: Offset Straight

16. Manufacturer & Model

REVISION DATE


INSTRUCTIONS FOR FILL FORM 20.28Page 1

AUG.940

PDVSA 20.28


GAGE GLASSES AND COCKS

1. Check what is to be supplied, and whether assembled or unassembled.

2. Select one type only per sheet.

3. Specify size, style and location of process connections. If side or backconnections are used, vent and drain connections are available.

4. Material of gage glass chamber and connections.

5. Specify minimum rating. It is assumed that a higher rating is also acceptable.

6. This section is used only if the option applies to all items listed on the sheet.Where options apply to certain items only, use the notes column instead.

7. Use for Manufacturer and Series or Type; detailed number may be listed in thetabulation.

8. Select style of cock, used.

9. Show connection sizes only.

10. Write in body and trim materials.

11. See Line 5 above.

12. Specify action and type of handle: plain closing or quick closing; handwheel orlever handle. This may be covered by the Model N given on Line 17.

13. Specify type of connection on each side: plain union, spherical union, solidshank. Give flange size, rating and type, if applicable.

14. Bonnet may be screwed, union type, or bolded:

15. Options checked here apply to all items. See line 6 above. Include specialpacking.

16. Fill in if required, or as a final record after selection is made.

CONN in tabulation refers to distance between center lines of vesselconnections. This figure, along with the visible glass dimension, defines thelength of the column. A secondary sheet with tabulation only may be made up ifrequired.


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PDVSA k-303

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