Alfa Laval Pump Handbook

5/26/2018 Alfa Laval Pump Handbook

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All you need to know ...

Alfa Laval Pump Handbook


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Second edition 2002

The information provided in this handbook is given

in good faith, but Alfa Laval is not able to accept any

responsibi lity for the accuracy of its content, o r any

consequences that may arise from the use of the

information supplied or m aterials described.


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Inside view

This pump handbook has been produced to supat all levels, providing an invaluable reference to

includes all the necessary information for the co

and successful application of the Alfa Laval rang

Liquid Ring and Rotary Lobe Pumps. The hand

into fifteen main sections, which are as follows:

1 Introduction

2 Terminology and Theory

3 Pump Selection

4 Pump Description

5 Pump Materials of Construction

6 Pump Sealing

9 Motors10 Cleaning G

11 CompliancStandards

12 Installation

13 Troublesho

14 Technical D


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ContentsSection 1: Introduction

Introduction of the Pump Handbook. 5

1.1 What is a Pump? 5

Section 2: Terminology and Theory

Explanation of the terminology and theory of

pumping applications, including rheology,

flow characteristics, pressure and NPSH. 7

2.1 Product/Fluid Data 8

2.1.1 Rheology 8

2.1.2 Viscosity 8

2.1.3 Density 12

2.1.4 Specific Weight 12

2.1.5 Specific Gravity 13

2.1.6 Temperature 13

2.1.7 Flow Characteristics 13

2.1.8 Vapour Pressure 172.1.9 Fluids Containing Solids 17

2.2 Performance Data 18

2.2.1 Capacity (Flow Rate) 18

2.2.2 Pressure 18

2.2.3 Cavitation 30

2.2.4 Net Positive Suction Head (NPSH) 31

2.2.5 Pressure Shocks (Water Hammer) 35

Section 3: Pump SelectionOverview of the pump ranges currently available from

Alfa Laval and which particular pumps to apply within

various application areas. 39

3.1 General Applications Guide 40

3.2 Pumps for Sanitary Applications 41

3.3 PumpCAS Selection and Configuration Tool 43

Section 4: Pump DescriptionDescription of Alfa Laval pump ranges including design,

principle of operation and pump model types. 45

4.1 Centrifugal Pumps 45

4.1.1 General 45

4.1.2 Principle of Operation 46

Section 5: Pump Materials o

Description of the materials, both m

elastomeric, that are used in the co

Alfa Laval pump ranges.

5.1 Main Components

5.2 Steel Surfaces

5.3 Elastomers

Section 6: Pump SealingExplanation of pump sealing princi

of the different sealing arrangemen

Alfa Laval pump ranges. A general

included, together with various ope

6.1 Mechanical Seals - Gener

6.2 Mechanical Seal Types

in Alfa Laval Pump Range

6.3 Other Sealing Options (Ro

Section 7: Pump Sizing

How to size an Alfa Laval pump from

performance data given, supported

and worked examples with a simple

7.1 General Information Requi

7.2 Power

7.2.1 Hydraulic Power7.2.2 Required Power

7.2.3 Torque

7.2.4 Efficiency

7.3 Centrifugal and Liquid Ring

7.3.1 Flow Curve

7.3.2 Flow Control

7.3.3 Alternative Pump Installati

7.4 Worked Examples

of Centrifugal Pump Sizing7.4.1 Example 1

7.4.2 Example 2

7.5 Worked Examples

of Centrifugal Pump Sizing

7.5.1 Example 1

7 5 2 Example 2


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Section 8: Pump Specifications Options

Description of the various specification options available

for the Alfa Laval pump ranges, such as port connections,

heating/cooling jackets, pressure relief valves and other

ancillaries. 157

8.1 Centrifugal and Liquid Ring Pumps 157

8.1.1 Port Connections 157

8.1.2 Heating/Cooling Jackets 158

8.1.3 Pump Casing with Drain 159

8.1.4 Increased Impeller Gap 159

8.1.5 Pump Inlet Inducer 159

8.2 Rotary Lobe Pumps 160

8.2.1 Rotor Form 160

8.2.2 Clearances 162

8.2.3 Port Connections 164

8.2.4 Rectangular Inlets 165

8.2.5 Heating/Cooling Jackets and Saddles 166

8.2.6 Pump Overload Protection 1678.2.7 Ancillaries 169

Section 9: MotorsDescription of electric motors, including information on motor

protection, methods of starting, motors for hazardous

environments and speed control. 173

9.1 Output Power 175

9.2 Rated Speed 1759.3 Voltage 176

9.4 Cooling 176

9.5 Insulation and Thermal Rating 176

9.6 Protection 177

9.7 Methods of Starting 179

9.8 Motors for Hazardous Environments 180

9.9 Energy Efficient Motors 182

9.10 Speed Control 184

9.11 Changing Motor Nameplates- Centrifugal and Liquid Ring Pumps only 186

Section 10: Cleaning GuidelinesAdvises cleaning guidelines for use in processes utilising

CIP (Clean In Place) systems. Interpretations of

cleanliness are given and explanations of the cleaning

12.2 Flow Direction

12.2.1 Centrifugal Pumps

12.2.2 Rotary Lobe Pump

12.3 Baseplates Founda

12.4 Coupling Alignmen

12.5 Special Considera

12.5.1 Pipework

Section 13: Troublesh

Advises possible causes an

problems found in pump ins

13.1 General

13.2 Common Problem

13.2.1 Loss of Flow

13.2.2 Loss of Suction

13.2.3 Low Discharge Pre

13.2.4 Excessive Noise o

13.2.5 Excessive Power13.2.6 Rapid Pump Wear

13.2.7 Seal Leakage

13.3 Problem Solving Ta

Section 14: Technical

Summary of the nomenclat

handbook. Various convers

shown.

14.1 Nomenclature

14.2 Formulas

14.3 Conversion Tables

14.3.1 Length

14.3.2 Volume

14.3.3 Volumetric Capaci

14.3.4 Mass Capacity

14.3.5 Pressure/Head

14.3.6 Force14.3.7 Torque

14.3.8 Power

14.3.9 Density

14.3.10 Viscosity Conversi

14.3.11 Temperature Conv

14.4 Water Vapour Pres


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...if pump

are thequestion

Alfa Laval is an acknowledged ma

leader in pumping technology, sup

Centrifugal and Positive Displacem


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1. Introduction

This section gives a short introduction of the Pu

1.1 What is a Pump?

There are many different definitions of thi

this is best described as:

A machine used for the purpose of tr

fluids and/or gases, from one place to

This is illustrated below transferring fluid

nozzles B.

Fig. 1.1a Typical pump installation


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Introduction

Alfa La

Centrif

and

Liquid

Fig. 1.1b Pump classifications

Pumps

Positive Displacement Rotodynam

Rotor Reciprocating Multi-Stage

Multi-Rotor Single Rotor Diaphragm Plunger End Suct

Screw Piston Simplex Proc

Circumferential Piston Archimedian Screw Multiplex Rubber

Gear Flexible Member Subme

Internal External Peristaltic Gene

Vane

Rotary Lobe Progressing Cavity

Alfa Laval

Rotary Lobe


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2. Terminology and The

In order to select a pump two types of d

Product/Fluid data which include

gravity, temperature, flow charac

and solids content.

Performance data which includes

inlet/discharge pressure/head.

Different fluids have varying characteristicunder different conditions. It is therefore

relevant product and performance data b

This section explains the terminology and theory

applications, including explanations of rheology

characteristics, pressure and NPSH.


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Terminology and Theory

2.1 Product/Fluid Data

2.1.1 Rheology

The science of fluid flow is termed Rheology a

important aspects is viscosity which is defined

2.1.2 Viscosity

The viscosity of a fluid can be regarded as a methe fluid is to flow, it is comparable to the frictio

causes a retarding force. This retarding force tr

energy of the fluid into thermal energy.

The ease with which a fluid pours is an indicatio

example, cold oil has a high viscosity and pours

water has a relatively low viscosity and pours qviscosity fluids require greater shearing forces t

fluids at a given shear rate. It follows therefore t

the magnitude of energy loss in a flowing fluid.

Two basic viscosity parameters are commonly

dynamic) viscosity and kinematicviscosity.

Absolute (or Dynamic) Viscosity

This is a measure of how resistive the flow of a

layers of fluid in motion. A value can be obtained

rotational viscometer which measures the force

spindle in the fluid. The SI unit of absolute visco

so-called MKS (metre, kilogram, second) syste

(centimetres, grams, seconds) system this is excentipoise (cP) where 1 mPa.s = 1 cP. Water at

20C () has the value of 1 mPa.s or 1 cP. A

usually designated by the symbol .

Kinematic Viscosity


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Relationship Between Absolute and K

Absolute and Kinematic viscosity are rela

where is the fluid densit

In the cgs system this translates to:

or

Absolute Viscosity (cP) = Kinematic Visc

A viscosity conversion table is included i

Viscosity Variation with Temperature

Temperature can have a significant effec

figure given for pump selection purposes

often meaningless - viscosity should alw

pumping temperature. Generally viscosit

temperature and more significantly, it inc

temperature. In a pumping system it can

increase the temperature of a highly visc

Newtonian Fluids

In some fluids the viscosity is constant re

applied to the layers of fluid. These fluids

At a constant temperature the viscosity

shear rate or agitation.

Typical fluids are:

Water Beer Hydrocarbons Milk M

Kinematic Viscosity (cSt) = Absolute

Specific

Fig. 2.1.2a Viscosity variation

with temperature

Viscosity

Temperature

Viscosity

Shear rate


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Non-Newtonian Fluids

Most empirical and test data for pumps and pip

developed using Newtonian fluids across a wid

However, there are many fluids which do not fol

these fluids are named Non-Newtonian fluids.

When working with Non-Newtonian fluids we us

to represent the viscous characteristics of the f

newtonian at that given set of conditions (shear

This effective viscosity is then used in calculatio

handbook information.

Types of Non-Newtonian FluidsThere are a number of different type of non-new

different characteristics. Effective viscosity at se

different depending on the fluid being pumped.

understood by looking at the behaviour of visco

in shear rate as follows.

Pseudoplastic FluidsViscosity decreases as shear rate increases, bu

be so high as to prevent start of flow in a norma

Typical fluids are:

Blood Emulsions Gums Lotions Soap

It is not always obvious which

type of viscous behaviour a

fluid will exhibit and

consideration must be given

to the shear rate that will exist

in the pump under pumping

conditions. It is not unusual to

find the effective viscosity as

little as 1% of the value

measured by standard

instruments.

Fig. 2.1.2d Vi

Viscosity

Normal

Viscometer

Reading

Fig. 2.1.2c Viscosity against shear rate

?

?

?

Viscosity

Shear rate

Viscosity


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Thixotropic Fluids

Viscosity decreases with time under she

ceases the viscosity will return to its orig

recovery will vary with different fluids.

Typical fluids are:

Cosmetic Creams Dairy Creams Gre

Anti-thixotropic Fluids

Viscosity increases with time under shea

ceases the viscosity will return to its orig

recovery will vary with different fluids. As

anti-thixotropic fluids have opposite rheo

thixotropic fluids.

Typical fluids are:

Vanadium Pentoxide Solution

Rheomalactic Fluids

Viscosity decreases with time under she

recover. Fluid structure is irreversibly des

Typical fluids are:

Natural Rubber Latex Natural Yoghurt

Plastic Fluids

Need a certain applied force (or yield stre

structure before flowing like a fluid

Fig. 2.1.2g Thixotropic Fluids

Viscosity

Time

Fig. 2.1.2h Anti-thixotropic Fluids

Visc

osity

Time

Fig. 2.1.2i Rheomalactic Fluids

Viscosity

Time


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2.1.3 Density

The density of a fluid is its mass per unit of volu

as kilograms per cubic metre (kg/m3) or pound

Density is usually designated by the symbol .

1 m of ethyl alcohol has a mass of 789 kg.

i.e. Density = 0.789 kg/m3.

2.1.4 Specific Weight

The specific weight of a fluid is its weight per un

usually designated by the symbol . It is related

= x g where g is gravity.

The units of weight per unit volume are N/m3 or

Standard gravity is as follows: g = 9.807

The specific weight of water at 20oC () and

follows:

Density in gases varies

considerably with pressure

and temperature but can be

regarded as constant in fluids.

Fig. 2.1.3a Density

1 ft

1ft

1

ft

Mass ofethyl alcohol

49.2lb

1 m

1m


789 kg1m


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2.1.5 Specific Gravity

The specific gravity of a fluid is the ratio o

water. As this is a ratio, it does not have

1 m of ethyl alcohol has a mass of 789

1 m of water has a mass of 1000 kg - it

Specific Gravity of ethyl alcohol is: 789

100

or

This resultant figure is dimensionless so

0.789.

2.1.6 TemperatureThe temperature of the fluid at the pump

concern as vapour pressure can have a s

performance (see 2.1.8).Other fluid prop

density can also be affected by temperat

of the product in the discharge line could

the pumping of a fluid.

The temperature of a fluid can also have

selection of any elastomeric materials us

A temperature conversion table is given

Temperature is a measure of

the internal energy level in a

fluid, usually expressed in

units of degrees Centigrade

(C) or degrees Fahrenheit (F).

Fig. 2.1.5a Specific gravity

1 m

1m

1m

Mass ofwater

1000 kg

1 m

1m


789 kg1m


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stream of water is no longer smooth and regula

moving in a chaotic manner. This type of flow is

The type of flow is indicated by the Reynolds n

Velocity

Velocity is the distance a fluid moves per unit of

equation as follows:

In dimensionally consistent SI units

Velocity V = Q where V = fluid v

A Q = capac

A = tube c

Other convenient forms of this equation are:

Velocity V = Q x 353.6 where V = fluid v

D Q = capac

D = tube d

or

or

Fluid velocity can be of great importance espec

slurries and fluids containing solids. In these inst


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Laminar Flow

This is sometimes known as streamline,

fluid moves through the pipe in concentr

velocity in the centre of the pipe, decreas

The velocity profile is parabolic, the grad

the viscosity of the fluid for a set flow-rat

Turbulent Flow

This is sometimes known as unsteady flo

taking place across the pipe cross sectio

more flattened than in laminar flow but re

the section as shown in fig. 2.1.7b.Turbu

at relatively high velocities and/or relative

Transitional Flow

Between laminar and turbulent flow there

transitional flow where conditions are uns

each characteristic.

Reynolds Number (Re)

Reynolds number for pipe flow is given b


Re = D x V x where D =

V =

=

=

This is a ratio of inertia forces

to viscous forces, and as such,

a useful value for determining

whether flow will be laminar or

turbulent.

Fig. 2.1.7a Laminar flow

V = velocityumax = maximum velocity

Fig. 2.1.7b Turbulent flow

V = velocityumax = maximum velocity


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Other convenient forms of this equation are:

Re = D x V x where D = tube d

V = fluid v

= densit

= absol

or

Re = 21230 x Q where D = tube d

D x Q = capac

= absol

or

or

Since Reynolds number is a ratio of two forces

given set of flow conditions, the Reynolds numb

using different units. It is important to use the sa

as above, when calculating Reynolds numbers.

Re less than 2300 - Laminar F

(Viscous f

system lo

Re in range 2300 to 4000 - Transition

(Critically b


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2.1.8 Vapour Pressure

Fluids will evaporate unless prevented fro

pressure. The vapour pressure of a fluid

temperature) at which a fluid will change

as absolute pressure (bar a or) - see

vapour pressure/temperature relationshi

pressure can be a key factor in checking

Head (NPSH) available from the system

Water will boil (vaporise) at a temperatur

- 0 C () if Pvp = 0.006 bar a

- 20 C () if Pvp = 0.023 bar a

- 100 C ( ) if Pvp = 1.013 ba

(atmospheric conditions at sea le

In general terms Pvp:

- Is dependent upon the type of flu

- Increases at higher temperature.

- Is of great importance to pump in

- Should be determined from relev

The Pvp for water at various temperature

2.1.9 Fluids Containing SolidsIt is important to know if a fluid contains

so, the size and concentration. Special a

regarding any abrasive solids with respe

construction, operating speed and shaft

Fig. 2.1.8a Vapour pressure

Pvp = Vapour pressure (external

pressure required to maintain as a fluid)

Temperature Va

0o C ( ) 0.

20o C ( ) 0.

100o C ( ) 1.


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2.2 Performance Data2.2.1 Capacity (Flow Rate)

The capacity (or flow rate) is the volume of fluid

certain area per time unit. This is usually a know

the actual process. For fluids the most common

litres per hour (l/h), cubic metres per hour (m/h

For mass the most commare kilogram per hour (kg/h), tonne per hour (t/h

2.2.2 Pressure

Pressure is defined as force per unit area:

where F is the force perpendicular to a surface a

surface.

In the SI system the standard unit of force is the

is given in square metres (m). Pressure is expr

Newtons per square metre (N/m). This derived

Pascal (Pa). In practice Pascals are rarely used common units of force are bar,

and kilogram per square centimetre (kg/cm).

Conversion factors between units of pressure a

14.3.5.

Different Types of PressureFor calculations involving fluid pressures, the m

relative to some reference pressure. Normally th

the atmosphere and the resulting measured pre

pressure. Pressure measured relative to a perfe

absolute pressure

Fig. 2.2.2a Pressure

F = Force

A

1 1


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Gauge Pressure

Using atmospheric pressure as a zero re

the pressure within the gauge that excee

atmospheric pressure. It is a measure of

exerted by a fluid, commonly indicated in

( ).

Absolute Pressure

Is the total pressure exerted by a fluid. It

pressure plus gauge pressure, indicated

absolute) or .

Absolute Pressure = Gauge Pressure +

Vacuum

This is a commonly used term to describ

system below normal atmospheric press

difference between the measured pressu

expressed in units of mercury (Hg) or uni

= 760 mm Hg ( ).

= 0 mm Hg ( ).

Inlet (Suction) Pressure

This is the pressure at which the fluid is e

reading should be taken whilst the pump

the pump inlet as possible. This is expres

or gauge bar g depending up

Outlet (Discharge) PressureThis is the pressure at which the fluid leav

reading should be taken whilst the pump

the pump outlet as possible. The reading

gauge bar .


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Example: Inlet Pressure above Atmospheric Pressure

Outlet Inlet Differe

4 bar g

( )

5.013 bar a

( )

0 bar g

( )1.013 bar a

( )

0 bar a

( )

1.5 bar g

( )

0 bar g

( )

1.013 bar a

( )

Differential = 4 - 1.5

or

= 58 -

-

Example: Inlet Pressure below Atmospheric Pressure

Outlet Inlet Differen

4 bar g

( )5.013 bar a

( )


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The Relationship Between Pressure a

In a static fluid (a body of fluid at rest) the

any two points is in direct proportion onl

between the points. The same vertical he

pressure regardless of the pipe configura

This pressure difference is due to the we

can be calculated as follows:


Static Pressure (P) = x g x h whereP =

=

g =

h =

Other convenient forms of this equation a

Static Pressure (P) = h (m

or

The relationship of elevation

equivalent to pressure is

commonly referred to as

head.

Fig. 2.2.2c Relationship of pressure to

elevation


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A pump capable of delivering 35 m ( ) hea

pressures for fluids of differing specific gravities

A pump capable of delivering 3.5 bar ( ) p

different amounts of head for fluids of differing s

Below are terms commonly used to express dif

pumping system which can be expressed as p

) or head units (m or ).

Flooded Suction

This term is generally used to describe a positiv

whereby fluid will readily flow into the pump inle

to avoid cavitation (see 2.2.3).

Fig. 2.2.2d Relationship of elevation to pressure

Water Slurry Solvent

35 m

().

35 m

()

35 m

()

3.5 bar

(50 psi)4.9 bar

(70 psi)

2.5

(35 SG 1.0 SG 1.4 SG 0.7

Water Slurry Solvent

35 m

( ).25 m

( ).

50 m

( ).

3.5 bar

(50 psi)

3.5 bar

(50 psi)

3.5

(50SG 1.0 SG 1.4 SG 0.7

Fig. 2.2.2e Relationship of elevation to pressure


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Total Static Head

The total static head of a system is the d

the static discharge head and the static s

Friction Head

This is the pressure drop on both inlet an

pump due to frictional losses in fluid flow

Dynamic Head

This is the energy required to set the fluid

any resistance to that motion.

Total Suction Head

The total suction head is the static suctio

head. Where the static head is negative,

greater than the static head, this implies

the centre line of the pump inlet (ie suctio

Total Discharge Head

The total discharge head is the sum of th

dynamic heads.

Total HeadTotal head is the total pressure difference

head and the total suction head of the pu

known value. It can be calculated by mea

installation conditions are specified.

Total head H =

Total discharge head Ht

=

Total suction head Hs

=


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In general terms: p > 0 for pressure.

p < 0 for vacuum.

p = 0 for open tank.

hs> 0 for flooded suction

hs< 0 for suction lift.

Pressure Drop

Manufacturers of processing equipment, heat e

mixers etc, usually have data available for presslosses are affected by fluid velocity, viscosity, tu

surface finish of tube and tube length.

The different losses and consequently the total

Pressure drop is the result of

frictional losses in pipework,

fittings and other processequipment etc.

Fig. 2.2.2g Fl

discharge tan

Fig. 2.2.2h Suction lift and open

discharge tanks

Fig. 2.2.2f Flooded suction and open

discharge tanks

Fig. 2.2.2i Su

discharge tan


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Example 1:

Table 2.2.2b

Fig. 2.2.2j Example

Process:

Pumping milk from tank A to tank G.

Q = 8 m3/h ( ).

Tubes, valves and fittings:

A: Tank outlet dia. 63.5 mm ( ).

A-B: 4 m ( ) tube dia. 63.5 mm (

A-B: 1 off bend 90 deg. dia. 63.5 mm

B-C: 20 m ( ) tube dia. 51 mm (

C: Seat valve type SRC-W-51-21-1

C-E: 15 m ( ) tube dia. 51 mm (

B-E: 3 off bend 90 deg. dia. 51 mm (

D: Non-return valve type LKC-2, 51

E: Seat valve type SRC-W-51-21-1

E-F: 46 m ( ) tube dia. 38 mm (

E-F: 4 off bend 90 deg. dia. 38 mm (F: Seat valve type SRC-W-38-21-1

The pressure drop through the tubes, va

determined as equivalent tube length, so

can be calculated.

The conversion into equivalent tube lengto section 14.7.This results in the follow

the different equipment as shown in the f

Equipment Eq

38 mm

A Tank outlet

A-B Tube

A-B Bend 90 deg.

B-C Tube

C-E Tube

Terminologyand Theory


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Table 2.2.2cEquipment Equivalen

1.5 in

A Tank outlet

A-B Tube

A-B Bend 90 deg.

B-C Tube

C-E Tube

C-E SRC seat valve, pos.3

B-E Bend 90 deg.

D LKC-2 non-return valve

E SRC seat valve, pos.5

E-F Tube 151

E-F Bend 90 deg. 4 x 3

F SRC seat valve, pos.3 13

Total 176

As viewed from the tables above the pressure

different equipment corresponds to the followin

length.

38 mm ( ) tube: Length = 54 m (51 mm ( ) tube: Length = 74 m (

63.5 mm ( ) tube: Length = 6 m (

The pressure drop through 100 m of tube for s

and 63.5 mm is determined by means of the fo

shown in 14.5.

~ 13.2


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The total pressure drop H in the proces

as follows:

38 mm: H = 54 x 13.2 = 7.13 m

100

51 mm: H = 74 x 3.0 = 2.22 m

100

63.5 mm: H = 6 x 1.1 = 0.07 m

100

H = 7.13 + 2.22 + 0.07 = 9.42 m 9.4

or

Process:

Pumping glucose with a viscosity of 500

through discharge pipeline as follows.

Tubes, valves and fittings:

30 m ( ) tube dia. 51 mm ( ).

20 m ( ) tube dia. 76 mm ( ).

Example 2:

Terminologyand Theory


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Table 2.2.2e

Table 2.2.2d

For the pipe fittings the conversion into equivale

carried out by reference to tables 14.7.This res

equivalent tube length for the different fittings as

Fittings Equivalent ISO Tub

51 mm

Non-return valve 2 x 12

Bend 90 deg. 6 x 1

Bend 90 deg.

Tee 3 x 3

Total 39

Fittings Equivalent ISO Tub

2 in

Non-return valve 2 x 39

Bend 90 deg. 6 x 3

Bend 90 deg.

Tee 3 x 10

Total 126

As viewed from the tables above the pressure

different fittings corresponds to the following eq

Tube dia. 51 mm : Length = 39 m


Applying the viscosity correction factor for 500

tube length is now:


Tube dia 76 mm : Length 4 m x 0


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Friction Loss Calculations

Since laminar flow is uniform and predict

in which the friction losses can be calcula

mathematical equations. In the case of tu

equations are used, but these are multip

normally determined by experimental me

known as the Darcy friction factor (fD).

The Miller equation given below can be ulosses for both laminar and turbulent flow

In dimensionally consistent SI units:

Where:Pf = pressure loss due to fric

fD

= Darcy friction factor.

L = tube length (m).

D = tube diameter (m).

V = fluid velocity (m/s).

= density of fluid (kg/m3).

Other convenient forms of this equation a

Where:

Pf = pressure loss due to fric

fD = Darcy friction factor.L = tube length (m).

D = tube diameter (mm).

V = fluid velocity (m/s).

SG = specific gravity.

The friction losses in a

pipework system are

dependent upon the type of

flow characteristic that is

taking place. The Reynolds

number (Re) is used to

determine the flow

characteristic, see 2.1.7.

Pf = fDx L x x V2

D x 2

Pf = 5 x SG x fDx L x V

D



32/256

For laminar flow, the Darcy friction factor (fD) can

from the equation:

fD

= 64

Re

For turbulent flow, the Darcy friction factor (fD) h

by reference to the Moody diagram (see sectio

necessary to calculate the relative roughness dsymbol .

Where:

= k

D

k = relative roughness which is the averag

internal surface peaks (mm).

D = internal pipe diameter (mm).

2.2.3 Cavitation

Cavitation is an undesirable vacuous space in th

pump normally occupied by fluid. The lowest prpump occurs at the pump inlet - due to local pr

of the fluid may evaporate generating small vap

bubbles are carried along by the fluid and implo

get into areas of higher pressure.

If cavitation occurs this will result in loss of pum

operation. The life of a pump can be shortened tdamage, increased corrosion and erosion when

When sizing pumps on highly viscous fluids car

select too high a pump speed so as to allow su

The relative roughness of pipes

varies with diameter, type of

material used and age of thepipe. It is usual to simplify this

by using a relative roughness (k)

of 0.045 mm, which is the

absolute roughness of clean

commercial steel or wrought

iron pipes as given by Moody.

The term cavitation is derived

from the word cavity, meaning

a hollow space.


33/256

2.2.4 Net Positive Suction Head (N

In addition to the total head, capacity, porequirements, the condition at the inlet of

system on the inlet side of the pump mu

to enter the pump at a sufficiently high p

This is called the Net Positive Suction He

NPSH.

Pump manufacturers supply data about required by their pumps (NPSHr) for sati

selecting a pump it is critical the net posit

(NPSHa) in the system is greater than the

required by the pump.

NPSHa is also referred to as N.I.P.A. (Ne

NPSHr is also referred to as N.I.P.R. (Net

A simplified way to look at NPSHa or N.I

of factors working for (static pressure an

(friction loss and vapour pressure) the pu

Providing the factors acting for the pumpacting against, there will be a positive suc

Fig. 2.2.4a NPSH balance

For

+

For satisfactory pump

operation:NPSHa > NPSHr

N.I.P.A. > N.I.P.R.



34/256

The value of NPSHa or N.I.P.A. in the system is

characteristic of the fluid being pumped, inlet pithe suction vessel, and the pressure applied to

vessel. This is the actual pressure seen at the p

important to note, it is the inlet system that sets

and not the pump. It is calculated as follows:

NPSHa or N.I.P.A. = Pa hs- h

Where:

Pa = Pressure absolute above fluid

hs

= Static suction head (m).

hfs

= Pressure drop in suction line (m

Pvp = Vapour pressure (bar a).

or

hs

NPSHa = Pressure acting on + Static suction Pressure drop

or surface of liquid (Pa) head (hs) (hfs)N.I.P.A.

+ve -ve +ve -ve

Fig. 2.2.4b NPSH calculation


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Process:

Water at 50 C ( ).

Pa = Pressure absolute above fluid l

( ).

hs

= Static suction head (3.5 m) (

hfs

= Pressure drop in suction line (1

Pvp = Vapour pressure (0.12 bar a =

NPSHr of pump selected = 3.0 m ( )

NPSHa = Pa - hs- h

fs- Pvp

= 10 - 3.5 - 1.5 - 1.2 (m)

= 3.8 m

As NPSHa is greater than NPSHr, no the conditions stated.

Process:

Water at 75 C (

).

Pa = Pressure absolute above fluid l

( ).

hs

= Static suction head (1.5 m) (

hfs

= Pressure drop in suction line (1

Pvp = Vapour pressure (0.39 bar a =

NPSHr of pump selected = 3.0 m ( )

NPSHa = Pa + hs- h

fs- Pvp

= 5 + 1.5 - 1.0 - 3.9 (m)

Example 1:

Fig. 2.2.4c Example

3.5 m 1.5 m

Example 2:

Fig. 2.2.4d Example

0.5 bar

1.5 m



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Process:

Glucose at 50 C ().

Pa = Pressure absolute above fluid level (1

( ).

hs

= Static suction head (1.5 m) ( ).

hfs

= Pressure drop in suction line (9.0 m) (

Pvp = Vapour pressure (assumed negligible

NPSHr of pump selected = 3.0 m ( ).

NPSHa = Pa + hs- h

fs- Pvp

= 10 + 1.5 - 9.0 - 0 (m) or

= 2.5 m

As NPSHa is less than NPSHr, cavitation wiconditions stated.

From the NPSHa formula it is possible to check

conditions which affect NPSHa.

The effects are shown as follows:

Example 3:

Fig. 2.2.4e Example

Fig. 2.2.4f Positive effect Fig. 2.2.4g Positive effect Fig. 2.2.4h N


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Suggestions for avoiding cavitation:

Keep pressure drop in the inlet linline as short as possible, diamete

minimal use of pipe fittings such a

Maintain a static head as high as

Reduce fluid temperature, althou

may have an effect of increasing

increasing pressure drop.

2.2.5 Pressure Shocks (Water Ha

The term shock is not strictly correct as

gases. The pressure shock is really a pre

propagation much higher than the veloci

1400 m/s for steel tubes. Pressure wave

changes in the velocity of the fluid in espe

The following causes changes in fluid

Valves are closed or opened.

Pumps are started or stopped.

Resistance in process equipment

meters, etc.

Changes in tube dimensions.

Changes in flow direction.

The major pressure wave problems in pr

to rapidly closed or opened valves. Pum

frequently started or stopped, can also c

When designing pipework systems it is i

frequency of the system as high as possand as many pipework supports as poss

excitation frequency of the pump.

Effects of pressure waves:



38/256

When for example, a valve is closed, the pressu

the valve to the end of the tube. The wave is thethe valve. These reflections are in theory continu

wave gradually attenuates cancelled by friction

A pressure wave as a result of a pump stoppin

than for a pump starting due to the large chang

continue much longer after a pump is stopped

starting. This is due to the low fluid velocity whicsmall damping of the pressure waves.

A pressure wave induced as a result of a pump

negative pressure values in long tubes, i.e. valu

absolute zero point which can result in cavitatio

pressure drops to the vapour pressure of the fl

Precautions

Pressure waves are caused by changes in the v

especially long runs of tube. Rapid changes in t

conditions of valves and pump are the major re

waves and therefore, it is important to reduce t

changes.

There are different ways to avoid or reduce pre

briefly described below.

Correct flow direction

Incorrect flow direction through valves can indu

particularly as the valve functions. With air-oper

incorrect direction of flow can cause the valve pagainst the valve seat inducing pressure waves

2.2.5bspecify the correct and incorrect flow di

valve.


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Damping of valves

The pressure wave induced by a seat vaminimised by damping the movement of

is carried out by means of a special dam

Speed control of pumps

Speed control of a pump is a very efficie

pressure waves. The motor is controlled

a frequency converter so that the pump

Started at a low speed which is s

speed. Stopped by slowly decreasing fro

lower speed or zero.

The risk of power failure should be taken

using speed control against pressure wa

Equipment for industrial processesThere is various equipment available to re

as:

Pressure storage tanks.

Pressure towers.

Damped or undamped non-retur

These however, may not be suitable for h

further advice may be required before th

in such installations.

Fig. 2.2.5c Oil damper for seat valve



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3. Pump Selection

As pumps are used in different

locations and stages of a

process the need for the

correct pump in the right place

has become increasingly

important. It is therefore

As demands on processes increase, ma

the quality of products and process profcorrect selection of a pump is of great im

The pump must be able to carry out vari

conditions.

Some of these are as follows:

Transfer various types of fluids/p

Gentle treatment of the fluids/pro

Overcome different losses and p

Provide hygienic, economical and

Ensure easy and safe installation,

Some pump problems can be:

The correct type of pump for the

The correct design of pump.

The correct selection of pump wi

conditions, product data, operati

Correct selection of shaft seals.

This section gives an overview of the pump rang

available from Alfa Laval and which particular pu

within various application areas.

Pump Selection


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3.1 General Applications Guide

The table shown below gives a general guide as to the various types

of Alfa Laval pump that may be required to suit the application.

General Requirements Centrifugal Liquid Ring

Product/Fluid Requirements

Max. Viscosity 1000 cP 200 cP

Max. Pumping Temperature 140C ( 284oF) 140C (284oF)

Min. Pumping Temperature - 10C ( 14oF) - 10C (14oF)

Ability to pump abrasive products Not recommended Not recommended

Ability to pump fluids containing air or gases Not recommended Recommended

Ability to pump shear sensitive media Fair Not recommended

Ability to pump solids in suspension Fair Not recommended

CIP capability (sanitary) Recommended Recommended

Dry running capability (when fitted with

flushed/quench mechanical seals) Recommended Recommended

Self Draining capability Recommended Recommended

Performance Requirements

Max. Capacity - m/hr 440 80

Max. Capacity - US gall/min 1936 352

Max. Discharge Pressure - bar 20 5.5

Max. Discharge Pressure - psig 290 80

Ability to vary flow rate Fair Not recommended

Suction Lift capability (primed wet) Recommended Recommended

Suction Lift capability (unprimed - dry) Not recommended Not recommended

Drive Availability

Air motor No No

Diesel engine No No

Electric motor Yes Yes


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3.2 Pumps for Sanitary A

The following table illustrates which Alfa L

used in various sanitary application areas

these pump ranges is given in section 4.

The Liquid Ring pump is used in most of

Fig. 3.2a Pump ranges

Pump Ranges from Alfa Laval

Centrifugal Liquid Ring

LKH LKH Multistage MR SRU

LKHP High Pressure LKHSP

LKHI LKH Ultra Pure

Alfa Laval Pump Ranges

Table 3.2a

Pump Type Pump Range Application

Centrifugal LKH

LKH-Multistage

LKHP-High Pressure

LKHSP

LKHI

LKH-Ultra Pure

Rotary Lobe SRU

SX

Brewe

ry

Confectionery

Dairy

OtherFood

Pharm

aceutical

Pump Selection


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Confectionery

Alfa Laval is a major supplier of pumping equipmproviding pumps to all the major confectionery

lobe pumps being used on high viscosity produ

chocolate, glucose, biscuit cream and fondant.

products that contain particulate matter, such a

be handled with the rotary lobe pump. Centrifug

commonly found on fat and vegetable oil applic

Dairy

Alfa Laval Centrifugal and Rotary Lobe pumps,

construction and conforming to 3-A standards

used extensively throughout the dairy industry o

cream and cultured products such as yoghurt.

Other FoodOther Food means other than Confectionery, D

generally Alfa Laval Centrifugal and Rotary Lobe

on general transfer duties handling products su

and flavourings.

Pharmaceutical

Alfa Laval Centrifugal and Rotary Lobe pumps capplications within this industry where hygiene a

resistance is paramount, such as cosmetic crea

toothpaste, perfume, shampoo and blood prod

Soap and Detergent

Alfa Laval Centrifugal and Rotary Lobe pumps c

applications within this industry, handling produsulphonic acid, fabric conditioner, dishwash liqu

ether sulphate, liquid detergent and surfactants

Soft Drink


45/256

Water

Alfa Laval Centrifugal pumps provide a lohigh purity water and water like applicatio

3.3 PumpCAS Selection

ToolPump selection for both Centrifugal and

made by the use of Alfa Lavals PumpCA

program prompts the user to enter pum

selects the pump from the product rang

application. The program selects both ce

pumps and provides the user with a comthe most appropriate technology to be c

technology is not suited to a specific app

physical limitations and or fluid character

the user, and recommend an alternative s

As well as performing the pump selectio

data from a comprehensive liquids databviscosity, SG, maximum speed, elastom

seal configuration. After the pump has be

assisted to complete a detailed pump un

include additional options such as pressu

cooling devices, connection specification

the pump and its configuration code (item

automatically generated aiding the quotaprocess.

In addition, PumpCAS will also provide d

pump with item numbers with all recomm

If you would like a copy of the

Alfa Laval PumpCAS

Pump Selection


46/256

Flexibility has been built in to the software to ena

to be answered without the need to complete aFor example, recommended spares lists can be

an existing configuration code or direct access

information relating to a specific pump technolo

The liquids database contained within PumpCA

rheological tests performed over many years on

Alfa Lavals chemical laboratory, and will be conadditional products are tested. All information is

purposes only.


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4. Pump Description

4.1 Centrifugal Pumps

4.1.1 General

The Alfa Laval range of Centrifugal Pump

specially for use in the food, dairy, bevera

chemical industries. Centrifugal pumps in

and those for high inlet pressure, can ha

applications. Centrifugal pumps can prov

solution.

Attributes include:

High efficiency.

Low power consumption.

Low noise level.

Low NPSH requirement.

Easy maintenance.

This section gives a description of Alfa Laval pu

including design, principle of operation and pum

Pump Description


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Fig. 4.1.2a Principle of operation

4.1.2 Principle of Operation

Fluid is directed to the impeller eye and is forcedmovement by the rotation of the impeller vanes

rotation, the impeller vanes transfer mechanical

impeller channel, which is formed by the impelle

then pressed out of the impeller by means of ce

finally leaves the impeller channel with increased

The velocity of the fluid is also partly converted

pump casing before it leaves the pump through

The principle of the multi-stage centrifugal pum

conventional centrifugal pump. The pump cons

several impellers (several stages) which increas

one stage to another but flow rate is unchanged

centrifugal pump operates as if several convent

pumps are connected in series.

4.1.3 Design

In general the Alfa Laval centrifugal pump does parts, with the pumphead being connected to a

motor. The impeller is fixed onto the pump shaft

pump casing and back plate these componen

below:

Impeller

The impeller is of cast manufacture and open tyvanes are open in front. This type allows visual

and the area between them.

A semi-open impeller is also available which is e

Fig. 4.1.2b Multistage centrifugal pump


49/256

Pump Casing

The pump casing is of pressed steel manscrewed connections and can be supplie

The pump casing is designed for

multi position outlet, with 360

flexibility.

Back Plate

The back plate is of pressed steel manuf

the pump casing form the actual fluid cha

transferred by means of the impeller.

Mechanical Seal

The connection between the motor shaft

casing is sealed by means of a mechanic

section 6.

Shroud and Legs

Most pump types are fitted with shrouds

shroud is insulated to keep noise to a mi

motor against damage.

Fig. 4.1.3b Pump casing

Fig. 4

Fig. 4.1.3d Back plate

Pump Description


50/256

Pump Shaft/Connections

Most pumps have stub shafts that are fixed to means of compression couplings, eliminating th

stub shaft assembly design provides a simple,

drive that reduces vibration and noise. On the m

pump the length of the pump shaft will differ dep

number of impellers fitted.

Adaptor

Most pumps are fitted with a standard IEC elec

connection between the motor and back plate

an adaptor, which can be attached to any stand

electric motor.

Pumps supplied with direct coupled motors ha

4.1.4 Pump Range

The Alfa Laval Centrifugal Pump portfolio comp

as follows:

LKH Range

The LKH pump is a highly efficient and economi

meeting sanitary requirements with gentle prod

chemical resistance.

Fig. 4.1.3f Compression coupling

Fig. 4.1.3g Adapter


51/256

LKH-Multistage Range

These pumps are primarily used in applicpressure and low capacity requirements

osmosis and ultra-filtration. The pumps a

four stage models (i.e. pumps fitted with

respectively).

Flow rates for 50 Hz up to 75 m/h (

pressures up to 40 bar ( ) with b

( ) and for 60 Hz up to 80 m3/h (

pressures up to 26 bar ( ).

For inlet pressures greater than 10 bar (

used incorporating fixed angular contact

LKHP-High Pressure Range

Fig. 4.1.4c LKH-Multistage Fig. 4

The LKH-Multistage range is

available in six sizes.Pump Size N

LKH-112

LKH-113

LKH-114

LKH-122

LKH-123LKH-124

Pump Description


52/256

The LKHP-High Pressure range is available in n

-15, -20, -25, -35, -40, -45, -50 and -60.

The pump range is designed for inlet pressures

( ). Flow rates for 50 Hz up to 240 m/h

with differential pressures up to 8 bar (

rates up to 275 m3/h ( ) with d

to 11 bar ( ).

For these high inlet pressures a special motor

contact bearings is used due to axial thrust.

LKHSP Range

The LKHSP self-priming pump is specially desig

fluids containing air or gas without loosing its pu

pump is for use in food, chemical, pharmaceuticindustries.

These pumps can be used for tank emptying o

where there is a risk of air or gas mixing with the

line. The pump is capable of creating a vacuum

upon pump size.

The pump is supplied complete with a tank, a n

(normally closed) on the inlet side, a tee and a n

(normally open) on the bypass line.

The LKHSP range is available in five sizes, LKH

and -40.

Flow rates up to 90 m/h ( ) and

for 50 Hz up to 8 bar ( ) and for 60 Hz,

LKHI Range

Fig. 4.1.4g LKHSP


53/256

For inlet pressures greater than 10 bar (

used incorporating fixed angular contact

LKH-UltraPure Range

These pumps are designed for high purit

water-for-injection (WFI). The pump is full

associated pipework, fittings and valves

pump is self-venting, due to the pump ca

The LKH-UltraPure range is available in fi

-20, -25, -35 and -40.

Flow rates up to 90 m/h ( for 50 Hz up to 8 bar ( and for

C Series range

The C-Series is the original, all-purpose A

less demanding applications.

The range is designed for meeting sanita

Cleaned-In-Place.

The C-series is produced mainly for the U

sizes, C114, C216, C218, C328 and C4

Fig. 4.1.4h LKH-UltraPure Fig. 4

Fig. 4.1.4j C-Series

Pump Description


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4.2 Liquid Ring Pumps

4.2.1 General

The Alfa Laval range of Liquid Ring Pumps are s

use in food, chemical and pharmaceutical indus

liquids containing air or gases. As the liquid ring

when half filled with fluid, it is capable of pumpin

partly filled with air or gases. As these pumps a

are ideally used as return pumps in CIP system

Attributes include:

Self-priming (when pump casing is half filled w

Suitable for aerated fluids.

High efficiency.

Minimal maintenance.

4.2.2 Principle of Operation

The liquid-ring pump is in principle a centrifugal

however, self-priming when half filled with fluid. T

capability is a result of the impeller design, sma

the impeller and the pump casing, and due to a

the pump casing and/or the front cover. The dis

routed 1 to 2 metres vertically upwards from thconnections to maintain the liquid ring in the sid



55/256

b) to c) The depth of the channel is still in

still forced outwards and consequbetween the vanes is increased u

where the channel has maximum

d) The vacuum created induces air f

the inlet at d.

d) to e) Air and fluid are circulated with ththe channel begins to decrease. T

vanes is gradually reduced as the

reduced and consequently press

the impeller.

e) The fluid is still forced outwards a

centre of the impeller. The same vinduced through the inlet is now e

e due to the pressure increase a

e) to a) The section between the vanes w

has passed the channel as only a

pumped. The cycle described ab

as the impeller has several sectio1500 rev/min. (50 Hz) or 1800 re

When all the air is removed from the suct

repeated for the fluid. The pump now op

4.2.3 Design

As for centrifugal pumps, the liquid ring p

parts the pumphead being connected

The impeller is fixed onto the pump shaft

and casing cover.

Pump Description


56/256

Pump Casing and Casing Cover

The pump casing is of cast manufacture complconnections and fittings or clamp liners. The pu

also of cast manufacture, with or without a chan

pump type/size. The pump casing and casing c

fluid chamber in which the fluid is transferred by

Mechanical Seal

The connection between the motor shaft/pump

casing is sealed by means of a mechanical seal,

section 6.

Shroud and Legs

Pumps fitted with standard IEC motors utilise t

used on the LKH centrifugal pump range.

Please note Alfa Laval Liquid Ring pumps fo

are supplied without shrouds.

Pump Shaft/Connections

Most pumps have stub shafts that are fixed to

Fig. 4.2.3d Pump with IEC standard

motor

Fig. 4.2.3b Pump with one channel Fig. 4.2.3c Pu


57/256

4.2.4 Pump Range

The Alfa Laval Liquid Ring Pump range is

MR Range

The MR range is available in four sizes, M

MR-200S and MR-300.

The pump range is designed for inlet pre

Flow rates up to 80 m/h (

of 5 bar ( ) for 50 Hz and 6 bar (

Fig. 4.2.4a MR-166S, MR-185S and

MR-200S

Fig. 4.2.4b MR-300 Fig. 4

Pump Description


58/256

4.3 Rotary Lobe Pumps

4.3.1GeneralThe Alfa Laval range of Rotary Lobe Pumps wit

pump element design has the ability to cover a

applications in industry. The hygienic design, an

steel construction and smooth pumping action

these pumps in the food, beverage, dairy and p

industries.

Attributes include:

Gentle transfer of delicate suspended solids.

Bi-directional operation.

Compact size with high performance and low

Ability to pump shear sensitive media.

Easy maintenance.

4.3.2Principle of OperationAlfa Laval ranges of Rotary Lobe pumps are of operating with no internal contacting parts in th

pumping principle is explained with reference to

which shows the displacement of fluid from pum

rotors are driven by a gear train in the pump ge

accurate synchronisation or timing of the rotors

contra-rotate within the pump head carrying flu

in the cavities formed between the dwell of the of the rotorcase.

In hydraulic terms, the motion of the counter ro

partial vacuum that allows atmospheric pressu


59/256

4.3.3Pump RangeAlfa Laval Rotary Lobe Pumps can be su

drive) or complete with drive such as ele

diesel or petrol engine (see 8.2.7).Range

SRU Range

The SRU pump range has been designe

duties throughout the brewing, dairy, foo

manufacturing processes.

The SRU range is available in six series e

displacements and two different shaft m

3

21 3

21

Horizontally ported pump (top shaft drive)

Vertically ported pump (left hand shaft drive)


Pump Description


60/256

The SRU pump range incorporates a universall

series 1 - 4. This gives the flexibility of mountingand outlet ports in either a vertical or horizontal

foot and foot position. For the larger series 5 an

or vertical plane inlet and outlet porting is achiev

dedicated gearbox castings. This pump range a

bore through porting complying with internation

BS4825/ISO2037, maximising inlet and outlet

NPSH characteristics.

Flow rates up to 106 m/h ( ) an

bar ( ).

The SRU range conforms to USA 3A requireme

SRU Build Selection SRU Model Displacement

Series

005

008

013

013

018

018

027

027

038

038

055

055

079

079

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

L or H

D

D

S

D

S

D

S

D

S

D

S

D

S

D

SRU1/005/LD or HD

SRU1/008/LD or HD

SRU2/013/LS or HS

SRU2/013/LD or HD

SRU2/018/LS or HS

SRU2/018/LD or HD

SRU3/027/LS or HS

SRU3/027/LD or HD

SRU3/038/LS or HS

SRU3/038/LD or HD

SRU4/055/LS or HS

SRU4/055/LD or HD

SRU4/079/LS or HS

SRU4/079/LD or HD

Litres/

rev

0.053

0.085

0.128

0.128

0.181

0.181

0.266

0.266

0.384

0.384

0.554

0.554

0.79

0.79

Pump

head

code

Gearbox

Shaft

Pump Nomenclature


61/256

SX Range

The SX pump range is designed to be usoperation is critical, suited to applications

biotechnology, fine chemical and special

range like the SRU range incorporates a

on series 1 - 4. This gives the flexibility of

inlet and outlet ports in either a vertical o

changing the foot and foot position. For

only vertical plane inlet and outlet portingdedicated gearbox casting. This pump ra

bore through porting complying with inte

BS4825/ISO2037, maximising the inlet a

pump and the NPSH characteristics.

The SX range has been certified by EHED

Equipment Design Group) as fully CIP cle

addition to being EHEDG compliant, the

the USA 3A standard and all media cont

compliant. All media contacting elastome

compression joints to prevent pumped m

(see section 6.2).

The SX range is available in seven series

displacements. Flow rates up to 115 m/

pressures up to 15 bar ( ).

Fig. 4.3.3b SX

Pump Nomenclature

SX Build Selection SX Model Displacement

Series

Pum

p

head

code

Gear

box

005

007

013

H or U

H or U

H or U

SX1/005/H or U

SX1/007/H or U

SX2/013/H or U

Litres/rev

0.05

0.07

0 128

Pump Description


62/256


63/256

5. Pump Materials of Con

5.1 Main Components

Pumps today can be manufactured from

materials dependent upon the product b

environment.

For Alfa Laval pump ranges this is genera

split into two main categories:

Product Wetted Parts(i.e. Metallic and elastomeric part

being pumped).

Non-product Wetted Parts

(i.e. Metallic and elastomeric part

being pumped).

Centrifugal and Liquid Ring Pumps

This section describes the materials, both meta

elastomeric, that are used in the construction of

pump ranges.

Main Pump Component Product Wetted Parts No

Adaptor AIS

Backplate AISI 316L or Werkstoff 1.4404

Impeller AISI 316L or Werkstoff 1 4404

Pump Materials of Construction


64/256

Rotary lobe pumps

Table 5.1b

Fig. 5.1b Rotary lobe pump

Rotorcase cover

RotorcaseProduct seal area

Ports

Gearbox

Drive shaft

Main Pump SRU Models SXComponent Metallic Product Metallic Non-product Metallic Product

Wetted Parts Wetted Parts Wetted Parts

Gearcase BS EN 1561:1977

grade 250 cast iron

Rotor Werkstoff 1.4404 or BS EN 10088-3:1995

316L, Non-galling grade 1.4404 or 316

alloy or rubber covered

Rotorcase BS 3100:1991 316 C12 BS3100:1991 316 C1

or 316L or 316L

or BS EN10088-3:19

grade 1.4404

Rotorcase Cover BS3100:1991 316 C12 BS3100:1991 316 C1

or 316L or 316L

or BS EN10088-3:1995 or BS EN10088-3:19

grade 1.4404 grade 1.4404

Shaft BS EN10088-3:1995 Duplex stainless stegrade 1.4404 or 316L (AISI 329 or

or duplex stainless steel BS EN10088-3:1995

(AISI 329 or grade 1.4462)

BS EN10088-3:1995

grade 1.4462)


65/256

5.2 Steel Surfaces

The standard machined surface finish o

the following methods:

Rumbling.

Shot blasting.

Electropolishing.

Mechanical (Hand) polishing.

Rumbling

This is achieved by vibrating the pump c

particulate such as stones and steel balls

Shotblasting

This method involves blasting finished co

particles at great force to achieve the sur

Alfa Laval centrifugal stainless steel pump

of stainless steel are used in this process

Electropolishing

This is an electro-chemical process in wh

component is immersed into a chemical

electrical current. A controlled amount of

surfaces evenly. The appearance is Sem

Mechanical (Hand) polishingThis is required when it is necessary to im

beyond that achieved by electropolishing

It typically involves:

Surface finish of product

wetted steel components has

become a major factor in the

food, pharmaceutical and

biotechnology industries

where hygiene and

cleanability are of paramount

importance.


S f R h


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Surface Roughness

The most commonly used surface roughness m

is defined as the arithmetic mean of the absolu

deviation of the profile from the mean line. Ra is

(m). The surface roughness can alternatively b

value. The Grit value specifies the grain size of t

grinding tool used.

The approximate connection between the Ra v

is as follows:

Ra = 0.8 m ( ) 150 Grit (3A standard).

Ra = 1.6 m ( ) 100 Grit.

For Alfa Laval Centrifugal and Liquid Ring Pumps see table below:

Fig. 5.2a Surface roughness

Pump surfaces Standard surface Optional surface O

roughness Ra (mm) roughness (3A finish) ro

by Rumbling method Ra (mm) by Mechanical R

(Hand) method bl

El

Product wetted surfaces < 1.6 ( 64 Ra) < 0.8 (32 Ra) <

External exposed surfaces < 1.6 ( 64 Ra) < 1.6 (64 Ra) <

Cast surfaces < 3.2 ( 125 Ra) 3.2 (125 Ra)

5 3 El t


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5.3 Elastomers

Alfa Laval pump ranges incorporate elas

and characteristics dependent upon app

the fluid being pumped.

Various elastomer types are specified be

the lifetime of elastomers as they will be a

e.g. chemical attack, temperature, mecha

The temperature range limitations given

the fluid being pumped. To verify satisfac

please consult Alfa Laval.

NBR (Nitrile) Available as O-rings or Quad-ring

Used as static or dynamic seals.

Resistant to most hydrocarbons,

Sufficiently resistant to diluted lye

Temperature range - minus 40C

( ).

Is attacked by ozone.

EPDM (Ethylene Propylene)

Available as O-rings or Quad-ring


Resistant to most products used

Resistant to ozone and radiation

Temperature range - minus 40C( ).

Not resistant to organic and non-

FPM (Fluorinated rubber)

A selection guide is shown insection 14.10.


PTFE (Polytetrafluoro Ethylene)


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PTFE (Polytetrafluoro Ethylene)

Can be used as cover for O-ring seals

(i.e. encapsulated).


Resistant to ozone.

Resistant to almost all products.

Temperature range - minus 30C min to

( ).

Not elastic, tendency to compression s

MVQ (Silicone)


Resistant to ozone, alcohols, glycols an

used within food industry.

Temperature range - minus 50C min to

( ).

Not resistant to steam, inorganic acids,

organic solvents.

FEP (Fluorinated Ethylene Propylene)

FEP covered (vulcanised) FPM or MVQ


Resistant to ozone.


Suitable for temperatures up to approx

More elastic than PTFE covered EPDM.

Kalrez (Perfluoroelastomer)


Resistant to ozone.


Temperature range minus 20C min to

Elastic.


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6. Pump Sealing

This section covers the shaft sealing dev

Centrifugal, Liquid Ring and Rotary Lobe

seals, other proprietary seals not detailedo-rings and lip seals can be found on the

A Pump is only as good as its shaft s

A successful pump application largely de

and application of suitable fluid sealing de

there is no single pump that can embracand applications whilst meeting individua

legislations, the same can be said of fluid

clearly illustrated by the large range of sh

mechanical and packed gland, that are a

manufacturer.

Shaft sealing devices used in Alfa Laval CRotary Lobe pumps include:

Mechanical Seals (see 6.2).

This section describes the principle of pump sealing and

sealing arrangements used on Alfa Laval pump ranges. A

guide is included, together with various operating parame

Pump sealing

Centrifugal and Liquid Ring pumps only have on


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Centrifugal and Liquid Ring pumps only have on

Rotary Lobe pumps employ a minimum of two

shaft). Generally all shaft seals are under press

gradient across the seal being from pumped flu

exceptions will be single internally mounted or d

product recirculation (single internally mounted

is greater than the pump pressure, resulting in t

being reversed.

Mechanical seals meet the majority of applicatio

these, single and single flushed seals are most f

The application of double mechanical seals is in

process demands for higher sanitary standards

requirements, particularly those related to emis

The majority of proprietary mechanical seals av

manufacturers have been designed for single sh

such as Centrifugal and Liquid Ring pumps. The

impose any radial or axial constraints on seal de

Rotary Lobe type pumps the need to minimise

beyond the front bearing places significant axia

were extended, the shaft diameter would increa

constraint - because shafts on a rotary lobe pum

plane, the maximum diameter of the seal must b

centres. Most designs therefore can only accom

customised seal design. This is not done to ta

advantage but it is as a consequence of the rot

concept.

Selection of shaft seals is influenced by mThere is often more than one


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Selection of shaft seals is influenced by m

Shaft diameter and speed

Fluid to be pumped

Temperature - effect on m

- can interfa

Viscosity - drag on se

- clogging o

- can interfa

maintained

- stiction at s

Fluid behaviour - does prod

work - ba

- can interfa

maintained

Solids - size?

- abrasivene

- density?

- clogging o

- can interfa

maintained

Thermal stability - what, if any

Air reacting - what, if any

Pressure - within seal

- fluctuations

- peaks/spik

- cavitation?

Services - flush?

- pressure?

- temperatu

- continuity?

There is often more than one

solution and sometimes no

ideal solution, therefore a

compromise may have to be

considered.

Pump sealing

6 1 Mechanical Seals - Gene


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6.1 Mechanical Seals Gene

Mechanical seals are designed for minimal leaka

majority of Centrifugal, Liquid Ring and Rotary L

arrangements.

Mechanical seal selection must consider:

The materials of seal construction, particfaces and elastomers.

The mounting attitude to provide the m

environment for the seal.

The geometry within which it is to be mo

A mechanical seal typically comprises:

A primary seal, comprising stationary an

Two secondary seals, one for each of th

rotary seal rings.

A method of preventing the stationary s

A method of keeping the stationary and

together when they are not hydraulically

pump is stopped. A method of fixing and maintaining the w

The Primary Seal

Comprises two flat faces, one rotating and one

support a fluid film, thus minimising heat genera

mechanical damage.

Commonly used material combinations are:

Carbon - Stainless

Carbon Silicon Ca

The Secondary Seal


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Carbon

Sta

inlessSteel

SiliconCarbide

Tun

gstenCarbide

Carbon

Sta

inlessSteel

SiliconCarbide

Tun

gstenCarbide

This is required to provide a seal betwee

the components with which they interfac

cushion mounting for the seat ring to red

stress i.e. shock loads.

Types of secondary seal are:

O-rings Cups Gaskets Wedges

For Alfa Laval pump ranges the o-ring is

secondary seal used. Its simple and vers

with the following comprehensive materi

NBR EPDM FPM PTFE MVQ

These are fully described in section 5.3.

Mechanical Seal Face/O Ring Material Availability

T bl 6 1

Rotary Stationary

Seal Face Seal Face

Pump Type Pump Range

Centrifugal/ LKH

Liquid ring LKH-Multistage

LKHP-High Pressure

LKHSP

LKHI

LKH-Ultra Pure

MR

Rotary Lobe SRU

SX (see note)

Note: SX1 pump has tungsten carbide seal faces, not silicon carbide seal faces.

Pump sealing

Working LengthOne of the main causes of


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The ideal design should eliminate/minimise pos

incorporating:

Physical position i.e. step on shaft Grub scr

Principle of Mechanical Seal Operation

The function of the assembly is a combination o

seal face flatness and applied spring force. Onc

operational, hydraulic fluid forces combine with

i.e. balance, which push the seal faces together

interface thickness to a minimum whilst increas

therefore minimising pumped fluid leakage.

Interface film

seal failure is for the seal

working length not being

correctly maintained.

Item

1

23

4

5

6

7

Fig. 6.1a Typical single mechanical seal

used in rotary lobe pumps

Fig. 6.1b Typical single mechanical seal

used in centrifugal pumps

3

2

4

1Pump shaft 5

Drive ring

Impeller Item

1

2

3

4

5

Working length

7

Aprox. 1 m

Fig. 6.1d Principle of mechanical seal

operation


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The gap between the seal ring surfaces i

principle of mechanical sealing.

Mechanical Seal Mounting

Most mechanical seals can be mounted e

External Mechanical Seals

The majority of mechanical seals used on

mounted externally, meaning that all the

mechanical seal (i.e. part of the rotary se

are not in contact with the fluid to be pum

mounted mechanical seal is considered e

inside of the stationary and rotary seal rin

o-rings are in contact with the fluid being

mechanical seals used on the SX rotary l

in 6.2,are an exception to this, as it is the

of the seal components that is in contact

Externally mounted seals have a lower pr

equivalent seal mounted internally.

Fig. 6.1e Typical external shaft seal

Spring forceFluidpressure

Rotating seal ring

operation

Rotating parts

Pump sealing

Internal Mechanical Seals

S h i l l d i ll


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Some mechanical seals are mounted internally,

the rotating parts are in contact with the fluid be

internal mechanical seal is designed with sufficie

the rotating parts so that it can be cleaned as e

and can withstand relatively high fluid pressures

For the Alfa Laval pump ranges, both the extern

mounted types of mechanical seal are available

flushed versions. The externally mounted mecha

Alfa Laval pump ranges is also available as a do

mechanical seal for some pump models. The ty

flushed and double flushed mechanical seal arra

described as follows:

Single Mechanical Seal

This is the simplest shaft seal version, which ha

described previously in this section. This seal ar

used for fluids that do not solidify or crystallise

atmosphere and other non-hazardous duties. F

operation it is imperative the seal is not subject

exceeding the maximum rated pressure of the p

must not be allowed to run dry, thus avoiding

faces, which may cause excessive seal leakage

Fig. 6.1f Typical internal shaft seal

Rotating parts

Fluid

Single Flushed Mechanical Seal

Th d fi iti f fl h i t id li


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The definition of flush is to provide a liq

selected seal arrangement. This seal arra

for any of the following conditions:

where the fluid being pumped ca

crystallise when in contact with th

when cooling of the seals is nece

fluid pumping temperature.

This seal arrangement used on externally

supply of liquid to the atmospheric side o

the seal area. The characteristics of the f

duty conditions will normally determine if

selecting a flushing liquid you must ensur

compatible with the relevant materials of

fully compatible with the fluid being pump

given to any temperature limitations that

liquid to ensure that hazards are not crea

The flushing liquid is allowed to enter the

i.e. 0.5 bar max to act as a b

This most basic flush system, sometime

provides liquid to the atmosphere side of

flushing away any product leakage. For t

the flushed seal comprises the same sta

the single seal, with the addition of a seal

connection and/or flushing tubes and a li

Fig. 6.1g Typical externally mounted

single flushed mechanical seal used in

rotary lobe pumps 12

Pump sealing

Fig. 6.1h Typical externally mounted

single flushed mechanical seal used in


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Typical applications are listed below, but full pro

performance data must be referred to the seal s

Adhesive Caramel Detergent Fruit Juice C

Jam Latex Paint Sugar Syrup Toothpa

Double Flushed Mechanical Seal

This seal arrangement is generally used with ho

i.e. high viscosity, fluid is hazardous or toxic. Th

used on Alfa Laval pump ranges is basically two

seals mounted back to back. This seal genera

same stationary and rotating parts as the single

of pump models, with the addition of a seal hou

connection and/or flushing tubes (dependent up

compatible flushing liquid is pressurised into the

pressure of 1 bar minimum above the d

the pump. This results in the interface film being

not the pumped liquid. Special attention is requ

faces and elastomers.

The arrangement in contact with the pumped flinboard seal, and the seal employed for the flu

to as the outboard seal. For Alfa Laval Centrif

of the outboard seal differs to the inboard seal.

g

centrifugal pumps Item

1

2

3

Fig. 6.1j Typical double flushed

mechanical seal used in centrifugal


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pumps

Table 6.1b

Table 6.1c

Typical applications are listed below, but

performance data must be referred to th

Abrasive Slurries Chocolate Glucos

PVC Paste Photographic Emulsion

General Seal Face Operating Parame

Tables below show general parameters

temperature, which should be noted whe

seal.

Viscosity Seal Face Combination

up to 4999 cP Solid Carbon v Stainle

Solid Carbon v Silicon

Solid Carbon v Tungste

up to 24999 cP Inserted Carbon v Sta

Inserted Carbon v Silic

Inserted Carbon v Tung

up to 149999 cP Silicon Carbide v Silico

Tungsten Carbide v Tu

above 150000 cP Consider Double Seals

Temperature Seal Face Combination

up to 150C (302oF) Inserted Carbon v Sta

Pump sealing

Flushing Pipework Layout

The suggested arrangement below is for single


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The suggested arrangement below is for single

If the pump is fitted with double mechanical sea

the pressure gauges and control valves should

side of the system. The choice of flushing liquid

compatibility with the pumping media and over

pressure and temperature. Usually water is use

water soluble products.

Fig. 6.1k Typical flushing pipework

layout for a rotary lobe pump

Fig. 6.1l Typical flushing pipework layout

for a centrifugal pump

*Pressure gauge

*Control valve

Suggested visible

indication of flow

Flush outlet to waste

Press

C

* Do

Free outlet

Mechanical Seal Selection Process

The illustration below describes the mech


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e ust at o be o desc bes t e ec

with relevant questions to be answered.

Fig. 6.1m Seal selection process

This should be used for

guidance purposes only, as

actual seal selections should

be verified by the seal

suppliers.

Obtain all Product/Fluidand Performance data

Select Seal Type

- Does fluid crystallise?- Is cooling required?- Will pump run dry?- Is aseptic barrier

required?

- Is fluid hazardous?- Is fluid abrasive?- Is fluid viscosity high?- Is temperature high?- Is aseptic barrier

required?

Use Single Seal

Select Seal Materials

Select Seal Faces Select Elastomers

Yes

Yes

No

No

Pump sealing

6.2 Mechanical Seal Types in


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Pump Ranges

R90 Type Mechanical Seals

Seal Option Availability for Centrifugal and Liquid Ring Pumps

Table 6.2a

Seal Option Availability for Rotary Lobe Pumps

Table 6.2b

Pump Range External Mounting Int

Single Single Flushed Double Flushed Single

LKH

LKH-Multistage

LKHP

LKHSP

LKHI

LKH-UltraPure

MR-166S, -200S

MR-300

Mechanical Seal Type Seal Name

Single externally mounted R90

R00

Hyclean

Single f lushed externally mounted R90

R00

Hyclean

Single flushed internally mounted R90

Double flushed R90

R00

Fig. 6.2a Hyclean single mechanical seal7


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R00 Type Mechanical Seals

The R00 type mechanical seals specifica

lobe pump range are fully front loading se

without the need for additional housings

changes. Specialised seal setting of the m

required as the seal is dimensionally set o

positioned in the fluid area minimise sheacontrolled compression joint elastomers

interfaces.Fig. 6.2b SX pumphead sealing

Fig. 6.2c R00 single mechanical seal

Front cover

compression joint Cup seal

Spline sealing

cup seal Squad ring

51 2 3 4

Pump sealing

6.3 Other Sealing Options (R


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Pumps only)

Packed Gland

The grade of packing used depends on the pro

and operating conditions. When packed glands

polyamide or PTFE packings will satisfy the ma

Provided the liquid being sealed contains no ab

does not crystallise, gland packings will function

stainless steel shafts or renewable stainless ste

instances of moderately abrasive fluids, such as

handled, the pumps should be fitted with hard c

which may be easily replaced when worn. Pum

packed gland seal are normally fitted with rubbe

between the gland followers and the gearcase f

slingers will reduce the possibility of the producgearcase lip seals, thereby overcoming any und

conditions that could arise in this area. When co

adjusted, a slight loss of product should occur

packing and shaft or sleeve, if fitted.

This seal arrangement is available on all SRU pu

This is a simple, low cost, and

easy to maintain controlled

leakage sealing arrangement.

These are specified for many

dirty applications, but when

possible, should always be

avoided for sanitary duties, as

they are less hygienic than

mechanical seals.

Fig. 6.3a Packed glandItem De

1 Sh2 Sh

3 Sp

4 Pa

5 Ga

6 G

7 G

8 Ri

9 G

9

A disadvantage with this seal arrangeme

will pass into the product causing a relat


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contamination, which cannot always be a

In common with all packed gland assem

occur but in this instance it will basically b

opposed to product being pumped.

This seal arrangement is available on all S

Fig. 6.3b Packed gland with lantern ring10

Pump sealing


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P Si i


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7. Pump Sizing

7.1 General Information R

In order to correctly size any type of pum

information is required as follows:

Product/Fluid Data

Fluid to be pumped.

Viscosity.

SG/Density.

Pumping temperature. Vapour pressure.

Solids content (max. size and concen

Fluid behaviour (i.e. Newtonian or Pse

Is product hazardous or toxic?

Does fluid crystallise in contact with a

Is CIP required?

Performance Data Capacity (Flow rate).

Discharge head/pressure.

Suction condition (flooded or suction

See section 2for detailed

descriptions of Product/Fluid

data and Performance data.

This section shows how to size an Alfa Laval pump

fluid and performance data given, supported by re

and worked examples with a simple step by step a

Pump Sizing

7.2 Power


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All of the system energy requirements and the e

pump must be supplied by a prime mover in the

energy. The rate of energy input needed is defin

expressed in watts (W) - for practical purposes

handbook is expressed in kilowatts (kW), i.e. w

7.2.1 Hydraulic PowerThe theoretical energy required to pump a give

against a given total head is known as hydraulic

horse power or water horse power.

This can be calculated as follows:

Hydraulic Power (W) = Q x H x x g

where: Q = capacity (m3/s)

H = total head/pressure (

= fluid density (kg/m)

g = acceleration due to g

Other forms of this equation can be as follows:

Hydraulic Power (kW) = Q x H

k

where: Q = capacity

H = total head/pressure

k = constant (dependent

Therefore

Hydraulic Power (kW) Q x H

or


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or

7.2.2 Required Power

The required power or brake horsepowe

pump shaft. This is always higher than th

energy losses in the pump mechanism (f

seals etc) and is derived from:

Required Power = x T

where: = shaft angular v

T = Shaft Torque

Shaft angular velocity = V x r

And is related to Hydraulic power by:

Required Power = Hydraulic Pow

Efficiency (100

Fig. 7.2.2a Shaft angular viscosity

V =

velocity

r = radius

Pump Sizing

7.2.3 Torque

Torque is defined as the moment of force requi

rotation and is usually expressed in units of Nm

The power requirements for

mechanical devices such as

pumps and pump drives are

Alfa Laval Pump Handbook

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Transcript of Alfa Laval Pump Handbook