Positive Displacement Pumps: A Guide to Performance Evaluation (AIChE Equipment Testing Procedure)

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Positive Displacement Pumps

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AlChE Equipment Testing Procedure

Positive Displacement Pumps A Guide to Performance Evaluation

Prepared by the

Equipment Testing Procedures Committee AlChE New York

B I C E N T E N N I A L

B I C E N T E N N I A L

WILEY-INTERSCIENCE A John Wiley & Sons, Inc., Publication

A I /""* UKiiC z\ir

It is sincerely hoped that the information presented in this document will lead to an even more impressive performance by the chemical processing and related industries. However, the American Institute of Chemical Engineers, its employees and consultants, its officers and directors, Equipment Testing Procedures Committee members, their employers, and their employers' officers and directors disclaim making or giving any warranties or representations, express or implied, including with respect to fitness, intended purpose, use or merchantability and/or correctness or accuracy of the content of the information presented in this document. Company affiliations are shown for information only and do not imply approval of the procedure by the companies listed. As between (1) the American Institute of Chemical Engineers, its employees and consultants, its officers and directors, Equipment Testing Procedures Committee members, their employers, and their employers' officers and directors, and (2) the user of this document, the user accepts any legal liability or responsibility whatsoever for the consequences of its use or misuse.

A joint publication of the Center for Chemical Process Safety of the American Institute of Chemical Engineers and John Wiley & Sons, Inc. Copyright © 2007 by the American Institute of Chemical Engineers. All rights reserved. Published by John Wiley & Sons, Inc., Hoboken, New Jersey. Published simultaneously in Canada. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, scanning, or otherwise, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without either the prior written permission of the Publisher, or authorization through payment of the appropriate per-copy fee to the Copyright Clearance Center, Inc., 222 Rosewood Drive, Danvers, MA 01923, (978) 750-8400, fax (978) 750-4470, or on the web at www.copyright.com. Requests to the Publisher for permission should be addressed to the Permissions Department, John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, (201) 748-6011, fax (201) 748-6008, or online at http://www.wiley.com/go/permission. Limit of Liability/Disclaimer of Warranty: While the publisher and author have used their best efforts in preparing this book, they make no representations or warranties with respect to the accuracy or completeness of the contents of this book and specifically disclaim any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives or written sales materials. The advice and strategies contained herein may not be suitable for your situation. You should consult with a professional where appropriate. Neither the publisher nor author shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages. For general information on our other products and services or for technical support, please contact our Customer Care Department within the United States at (800) 762-2974, outside the United States at (317) 572-3993 or fax (317) 572-4002. Wiley also publishes its books in a variety of electronic formats. Some content that appears in print may not be available in electronic format. For information about Wiley products, visit our web site at www.wiley.com. Wiley Bicentennial Logo: Richard J. Pacifico Library of Congress Cataloging-in-Publication Data is available. ISBN 978-0-470-18097-6 Printed in the United States of America. 10 9 8 7 6 5 4 3 2 1

Positive Displacement Pumps

AMERICAN INSTITUTE OF CHEMICAL ENGINEERS EQUIPMENT TESTING PROCEDURES COMMITTEE Chair: Richard P. O'Connor R.P. O'Connor and Associates, LLC POSITIVE DISPLACEMENT PUMPS PROCEDURE SUBCOMMITTEE Chair: L. Nelik, Ph.D., PE, APICS Pumping Machinery Company

Go-Chair: Luis F. Rizo, PE GE Plastics

General Committee Liaison: Prashant Agrawal, PE Kellogg Brown and Root S. Dennis Fegan, Hermetic Pumps, Inc. & Robert J. Hart, E.I. du Pont (Retired)

Working Committee Bearings and Rotor Dynamics Section Diaphragm Pumps Section Dr. G. Kirk G. Lent University of Virginia Wilden Pumps Piping Section L.F. Rizo, PE GE Plastics

Progressing Cavity Section A. Wild Moyno Industrial Products

Reciprocating Pumps Section L. Warren Cat Pumps

Reliability Section J. Joseph Amoco

Rotary Section J. Brennan IMO Pump

Rotary Section J. Purcell Roper Pump

Seals Section J. Netzel John Crane

Approved for publication by AlChE's Chemical Engineering Technology Operating Council on February 16, 2007.

AlChE Equipment Testing Procedure Equipment Testing Procedures Committee Chair: Richard P. O'Connor, P.E. R.P. O'Connor and Associates, LLC Vice Chair: James D. Fisher, P.E. Amgen, Inc. Past Chair: P. C. Gopalratnam, Ph.D., P.E. INVISTA S.a.r.l. CTOC Liaison: Gavin Towler UOP AlChE Staff Liaison: Stephen Smith

General Committee Members Prashant D. Agrawal, P£ KBR

Robert E. McHarg, P£ UOP (Retired)

S. Dennis Fegan Hermetic Pumps, Inc.

Anthony L. Pezone, PE Consultant

J.F. Hasbronck, PE Hasbrouck Engineering

Rebecca Starkweather, PE Scientex LC

Dr. John G. Knnesh, PE FRI (Deceased)

Thomas H. Yohe, PE Yohe Consulting

VI

Positive Displacement Pumps

Table of Contents 100.0 INTRODUCTION

1

200.0 EXTENDED DEFINITIONS OF MAJOR TERMS, WITH EXPLANATIONS, CONVERSION FACTORS, AND NOMENCLATURE 3 200.1 Positive Displacement Pump 3 200.2 Fluid versus Liquid 3 200.3 Flow 3 200.4 Pressure 3 200.5 Net Positive Inlet Pressure (NPIP) 3 200.6 Power 4 200.7 Efficiency 4 200.8 Torque 5 200.9 Viscosity 5 200.10 Specific Gravity 5 200.11 Revolutions per Minute (rpms) 5 200.12 Extended Definitions 5 300.0 TYPES OF PUMPS COVERED IN THIS PROCEDURE 7 300.1 Gear Pumps 8 300.2 Lobe Pumps 9 300.3 Multiple Screw Pumps 9 300.4 Vane Pumps 10 300.5 Progressive Cavity Pumps 11 300.6 Diaphragm Pumps 11 300.7 Piston/Plunger Pumps 12 400.0 GENERAL NOTES ON TEST PREPARATION L O G I S T I C S INSTRUMENTS AND METHODS OF MEASUREMENT 400.1 Flow 400.2 Pressure 400.3 Power and Efficiency 400.4 Temperature

13 13 13 13 15

500.0 TESTING ROTARY PUMPS (GEAR, MULTIPLE SCREW, LOBE, AND . . . . 16 VANE PUMPS) 501.0 Test Equipment 17 501.1 Shaft Speed 17 501.2 Suction and Discharge Pressures 17 501.3 Fluid Viscosity at Range of Temperatures 17 501.4 Flow Rate 18 501.5 Input Power 18 502.0 Standardized Tests 18 502.1 Performance Test 18 502.2 Minimum Required Suction Pressure Test 20 vii

AlChE Equipment Testing Procedure 503.0 Other Tests 503.1 Sound Pressure Level 503.2 Vibrations and Temperature 504.0 Test Process Example 504.1 Performance Test 504.2 Observations 504.3 Minimum Required Suction Pressure Test 504.4 Observations 504.5 Other Tests

22 23 23 23 24 27 29 30 30

600.0 PROGRESSIVE CAVITY PUMP TESTING 601.0 Test Equipment 601.1 Shaft Speed 601.2 Pressure Instrumentation 601.3 Fluid Viscosity 601.4 Flow Measurement 601.5 Input Power 602.0 Tests 602.1 Performance Tests 602.2 NPSH Test 603.0 Other Tests 603.1 Sound Pressure Level 603.2 Vibration Measurements 603.3 Temperature Measurements 603.4 Miscellaneous

31 31 31 32 32 32 33 33 34 34 34 34 34 35 35

700.0 AIR-OPERATED DIAPHRAGM PUMPS 700.1 Recommended Installation 700.2 Access 700.3 Air Supply 700.4 Elevation 700.5 Flexible Connections 701.0 Test Equipment 701.1 Inlet Air Pressure 701.2 Fluid Discharge Pressure 701.3 Fluid Inlet Pressure 701.4 Process Fluid Temperature 701.5 Environment and Inlet Air Temperature 701.6 Viscosity 701.7 Specific Gravity 701.8 Ambient and Inlet Air Relative Humidity 701.9 Air Consumption 701.10 Flow

36 36 36 36 36 36 37 37 37 38 38 38 38 39 39 39 39

vm

Positive Displacement Pumps 701.11 Sound 701.12 Blow-by 702.0 Tests 702.1 Performance Test 702.2 Life Test 703.0 Other Tests 703.1 Blow-by 703.2 Dry Vacuum 703.3 Wet Vacuum 703.4 Sound Test 704.0 Field Test Process Example 704.1 Performance Test 704.2 Observation

40 41 41 41 44 44 44 44 45 46 46 47 47

800.0 RECIPROCATING POSriWE DISPLACEMENT PUMP (RPDP) TESTING 800.1 Safety Precautions 800.2 Piping 800.3 Test Objective 801.0 Test Equipment 801.1 Shaft Speed 801.2 Suction Pressure 801.3 Discharge Pressure 801.4 Differential Pressure 801.5 Crankcase Temperature 801.6 Liquid Temperature 801.7 Vapor Pressure 801.8 Viscosity 801.9 Flow Rate 801.10 Input Power 802.0 Standardized Tests 802.1 Performance Test 802.2 Inlet Pressure Trace 803.0 Other Tests 803.1 Sound Pressure Level 803.2 Analysis of Results 804.0 Test Process Example

51 51 51 52 53 53 53 54 54 54 55 55 55 55 56 56 56 57 57 57 57 57

900.0 AUXILIARIES 900.1 Appendix A: Seals 900.2 Appendix B: Bearings and Rotor Dynamics 900.3 Appendix C: Piping 900.4 Appendix D: Installation

61 61 63 64 65

1000.0 REFERENCES AND BIBUOGRAPHY

73

IX

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AlChE Equipment Testing Procedure

List of Figures Figure 1. Types of positive displacement pumps

7

Figure 2: Types of kinetic (centrifugal) pumps

8

Figure 3: External gear pump

9

Figure 4: Internal gear pump

9

Figure 5: Lobe pump internals

9

Figure 6: Two-screw pump

9

Figure 7: Three-screw pump

9

Figure 8: Vane pump

10

Figure 9: Progressive Cavity pump

11

Figure 10: Diaphragm pump in operation

11

Figure 11: Piston pump cross-section

12

Figure 12: Installation and set-up for pump performance field test

19

Figure 13: Example of pump performance curves

20

Figure 14: Minimum suction pressure test set-up

21

Figure 15: Minimum suction pressure results

22

Figure 16: Sample installation for a rotary pump test

25

Figure 17: Performance curve drawn from data in Table 6

27

Figure 18: Performance comparison to the manufacturer's catalog curve

28

Figure 19: Minimum required suction pressure test graph

30

Figure 20: Typical installation of a test pump

37

Figure 21: Typical installation of a pump test system

47

Figure 22: Sample flow curve

50

Figure 23: Horizontal triplex pump

58 xi

Positive Displacement Pumps Figure 24: Typical anchors for the pump piping

65

Figure 25: Rough alignment phase

66

Figure 26: Baseplate leveling pads and grout location

67

Figure 27: Typical anchor bolt and leveling wedges

67

Figure 28: Potential bolt-bound situation due to tight clearances between bolt, feet, and base

68

Figure 29: Rough alignment after grouting

69

Figure 30: Final connection of the suction piping

69

Figure 31: Final piping

70

Figure 32: Overhead view of the motor and pump

71

Figure 33: Piping alignment verification

72

List of Tables Table 1: Basic conversion factors

6

Table 2: Typical power factor correction table

14

Table 3: Performance test report form

16

Table 4: Time trending of basic parameters

24

Table 5: Raw performance data for rotary pump test

26

Table 6: Calculated parameters for performance test

26

Table 7: Minimum required suction pressure test (field data)

29

Table 8: Datasheet for field test of air-operated diaphragm pump

40

Table 9: Flow test datasheet showing start-up pressure

42

Table 10: Test inspection log for life test

43

Table 11: Vacuum test datasheet

45

Table 12: Sound test datasheet

46 xii

AlChE Equipment Testing Procedure Table 13: Example of a field test datasheet for an air-operated diaphragm pump in a water transfer application

48

Table 14: Data from a sample flow test

49

Table 15: Data collection table for reciprocating pump test

52

Table 16: Test results

58

Table 17: Calibration table

59

Table 18: Inlet pressure trace

60

Table 19: Materials data for pump internals

63

Xlll

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Positive Displacement Pumps

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Positive Displacement Pumps 100.0 INTRODUCTION The main objective in creating this document is to provide pump users with a concise, easy to read, illustrated field-testing procedure. The goal was to take into account the "imperfect" realities of actual field conditions, with all the obvious restrictions and emphasis on plant uptime. Pump testing has previously been addressed in a number of documents, including The Hydraulic Institute [1] (testing), API 610 [2] (centrifugal pumps), and API 676 [3] (rotary gear pumps). But, the test procedures covered in these documents focus primarily on testing at the pump manufacturers' own facilities. Such tests are accurate, repeatable, and reliable, but are difficult to duplicate in the field, where access to specialized test instrumentation is often difficult or impractical. For example, torque meters are routinely used by manufacturers for testing. These devices, which can measure torque and speed, and can perform internal conversion to calculate power, are only used temporarily as auxiliary devices, and are not installed in the field between the pump and a driver. Therefore, a user cannot readily measure pump input torque to calculate the horsepower, even if the rotational shaft speed is known. Reading the motor current, however, is relatively straightforward, and so, for field operators, a method that converts from current to power, even if some accuracy is sacrificed, would be useful. Another example is a requirement of a certain length of piping at the pump inlet, as well as before measuring devices (gauges, flow meters). Rarely, if ever, do such "perfect" accommodations exist in the field. Obviously, the accuracy of measurements cannot be expected to be as good as at the manufacturers' test facilities. The need to differentiate between the more accurate pump manufacturer test facilities and field testing methods has been recognized in the past, in AlChE Equipment Testing Procedures for Centrifugal and Rotary Positive Displacement Pumps, [4,5]. Reading them now, these documents are not outdated, but do have two major shortcomings. First, they are focused on rotary pumps, and for Newtonian liquids only. Second, their style is too "academic" for use by those who operate the pumps. A complete revision and rewrite of the field testing procedure to include the positive displacement pump types now commonly used at chemical plants and related facilities is long overdue. Since the introduction of the first field-testing procedure in 1968, a large number of new chemicals have been introduced by the rapidly expanding industry. NonNewtonian fluids can no longer be considered an exception, and pump-testing procedures must incorporate such cases. There are numerous examples of pumpage that is not liquid, but is a fluid in a more general sense. Paper pulp, slurries, waste sludge, and adhesives are all examples of fluids that, at least by appearance, do not resemble a liquid at all.

1

AlChE Equipment Testing Procedure The style of this Procedure is simple and practical. It is hoped that it would be easy and interesting to read, and could be useful for the internal training of plant personnel, as well as for expanding the general existing literature on pump fundamentals and reliability, such as [6], [7], [8].

2

Positive Displacement Pumps 200.0 Extended Definitions of Major Terms, with Explanations, Conversion Factors, and Nomenclature Note: All calculations and data in this document are measured using common sets of U.S. units. To convert to metric units, refer to the conversion factors given at the end of this section. To make the document more useful, definitions are accompanied by short explanations relating to pump operating principles.

200.1

Positive Displacement (PD) Pump

In common terms, a pump is thought of as a device from "flange-to-flange," that is, between the suction and discharge flanges, thus differentiating it from the "system," which would include the motor, coupling, baseplate, tanks, connecting piping, and controls. A PD pump can be thought of as a "flow generator," as compared to a centrifugal pump, which can be imagined as a "pressure (or head) generator."

200.2

Fluid versus Liquid

200.3

Flow

200.4

Pressure

200.5

Net Positive Inlet Pressure (NPIP)

A fluid is a substance that is unable to resist even the slightest amount of shear without flowing. Liquids, gases, and vapors are fluids, but liquids are practically incompressible, except at very high pressures. This is a volume of fluid per unit of time. The ideal flow disregards "slip," or the portion of flow that "slips" back through the internal clearances from discharge side to suction, driven by the differential pressure across the pump. The net flow is what actually comes out from the pump exit into the discharge pipe. Another term often used interchangeably with flow is "capacity." There are discharge, suction, and differential pressure terms. It is very important to specify gauge (psig), absolute (psia), or differential (psid) pressure; mistakes are common, especially for cases of suction vacuum. Actual available suction pressure must be greater than the minimum required suction pressure, in order to avoid adverse effects on pump operation, such as flow loss, cavitation, noise, vibration, and so forth. The subject of NPIP is analogous to that of NPSH (net positive suction head) in centrifugal pumps. Traditionally, however, inlet conditions for positive displacement pumps have been defined in pressure terms, rather then in head terms. NPSH, given in feet of liquid (or meters if metric units are used), is basically the pump inlet head minus the head equivalent to vapor pressure of the pumped fluid. Since density has already been used in converting pressure terms into head, NPSHR (required NPSH for a centrifugal pump) is not a function of density (or specific gravity). It depends on the inlet geometry of the centrifugal pump, and rotating speed (approximately as a square of rpm).

3

AlChE Equipment Testing Procedure NPIP, on the other hand, is the pump inlet pressure minus the fluid vapor pressures. PD pumps typically operate in systems with low inlet velocities. In these cases, the velocity head portion (dynamic head) has historically been ignored. NPIPR, with the "R" signifying "pump required," is the difference between the inlet pressure and the vapor pressure—corrected to the centerline of the pump inlet port—necessary for the pump to operate without a reduction in flow. The Hydraulic Institute defines the minimum required pressure (or equivalent NPIPR) as such where 5% of the flow reduction occurs due to cavitation. For positive displacement pumps, any increase in NPIPA, with the "A" signifying "pump available," has no effect on volumetric efficiency, as long as NPIPA is above the NPIPR. Low values of NPIPA may result not only in flow reduction, but also in significant pressure spikes, vibrations, noise, and possible damage to the pump.

200.6

Power

200.7

Efficiency

Power is defined as energy per unit of time. The gross power delivered by the driver to the pump is called break horsepower (BHP), and net power delivered to fluid by the pump is called hydraulic, orfluid power (FHP), and can be calculated as the product of the differential pressure times theoretical flow, with the appropriate coefficient, plus internal viscous power losses. The difference between the break and hydraulic power is due to the internal losses, or the sum of mechanical and volumetric losses. Historically, an overall pump efficiency assessment has not been as widely used with PD pumps as with centrifugal pumps. Volumetric efficiency has been a much more common method of comparison between different designs and applications. Positive displacement pumps are inherently constant flow machines with regard to differential pressure. In theory, a constant volume of fluid is "displaced" with every rotation, stroke, or cycle— hence the name. However, because of the internal clearances, a certain amount of fluid "slips" back from the discharge side to suction. This slip depends on the lateral and radial clearances, and on the overall differential pressure which drives it. The higher the viscosity of the fluid, the more it resists the slip. The net actual flow is the difference between the ideal, or theoretical flow, and the slip: Qa = Q o - Q s l i p

(200.7.1)

which can be also expressed in terms of volumetric efficiency:

4

Positive Displacement Pumps The overall efficiency, often called "mechanical efficiency" in PD pumps, is a ratio of useful hydraulic power (FHP) transmitted to the fluid exiting the pump, to a total power (BHP) absorbed by the pump:

(200.7.2) 200.8

Torque

200.9

Viscosity

200.10

Specific Gravity

200.11

Revolutions per Minute (rpms)

Torque is a measure of the machine's ability to move the resisting loads—power divided by rotating speed in rpm, with an appropriate coefficient, depending on die units. For the same power, the torque is greater at low speed. For example, a speed reducer increases torque. Viscosity is defined as a fluid property that characterizes its ability to resist motion. Dynamic viscosity is a coefficient between the fluid shear rate and shear stress. Kinematic viscosity is equal to dynamic viscosity divided by the specific gravity. This is a major parameter influencing pump operation. Pump power goes up with viscosity to overcome the internal hydraulic viscous drag. Suction conditions become more demanding with increased viscosity, reflecting the ability of the fluid to get to the pump suction port, and fill its displacement mechanism (gears, screws, etc.). Kinematic viscosity is measured in centistokes (cSt); dynamic viscosity is measured in centipoise (cP). Other common units of dynamic viscosity are Saybolt Seconds Universal (SSU). Refer to charts for exact conversions, but a good rule of thumb is cP x 5 = SSU, for viscosity above approximately 50 cP This is a ratio of fluid density to water density at 60 °F at atmospheric pressure. In the 1980's, it became common and fashionable to use smaller, faster running pumps, as opposed to larger, slower running pumps, for obvious cost reasons. However, with speed came trouble, as many maintenance and reliability plant personnel discovered. A faster running pump requires more suction pressure, and also wears out disproportionately faster. Today, it is important to consider not only initial cost, but also wear, suction requirements, vibration, and so forth, to strike a balance between speed and reliability, for a given flow requirements.

200.12

Extended Definitions Q

Pump net flow, gpm

QQ

Pump theoretical flow, disregarding slip, gpm

Q s |jp

Pump slip, gpm.

BHP

Pump input power, hp

5

AlChE Equipment Testing Procedure rpm Ps

Pump shaft rotational speed, revolutions per minute Pump suction pressure (usually in absolute units, psia or psig)

Pd Ap

Pump discharge pressure (usually gauge units, psig)

v

Kinematic viscosity of the pumped fluid, centistokes

\i

Dynamic viscosity, centipoises (cP)

Ps

Minimum required suction pressure

Differential pressure (psi or psid)

(expressed in absolute units, psia) ^vol

Volumetric efficiency

^mech

Mechanical efficiency Overall efficiency

PF

Motor power factor

'H motor

Motor efficiency

T

Torque, in lbs.

Table 1: Basic conversion factors Flow

Convert from GPM (US) GPM (US)

Pressure and head

Divide by 4.403 15.9

Convert to m3/HR liters/sec

Convert from psi psi psi

Divide by 14.7 14.5 145

Convert to Atm Bars MPa

Convert from HP

Multiply by 0.746

Convert to KW

If needed, other conversion formulas may be found in standard engineering texts and data tables.

6

Positive Displacement Pumps 300.0 Types of Pumps Covered in this Procedure

The two major classes of positive displacement pumps are rotary and reciprocating. In industry, where this AlChE procedure mostly applies, the majority of applications are handled by the following pump types, which form the basis of this procedure: a) Rotary (gear, lobe, screw, and vane) b) Progressive Cavity c) Diaphragm d) Piston/Plunger

Figure 1: Types of positive displacement pumps Used courtesy of The Hydraulic Institute (1)

7

AlChE Equipment Testing Procedure

,—, Closed coupled Single or Two Stage

1

End Suction (Including submerslbles)

1

In-line

1

Separately coupled Single and T w o Stage"

«0 _

3 _

O Impeller between bearings

.

_ . . , . i Separately coupled __J Single and Two Stage I

—

Separately coupled Multistage

1 Radial (Vert.) Split case ,

ss.

Vertical type s ingle and Multistage

i

Turbine type

! — Regenerative turblr e

In-line Frame mounted Centering support API 610 _ Frame mounted Ansl B:73.1 Wet Pit Volute Axial flow Impeller/propeller Volute type Hor/Vert 1 Axial (Hor.) Split case v ' 1 Radial (Vert.) Split case Axial (Hor.) Split case Deep well turbine Including Submerslbles Barrel or can pump Short setting or closed coupled Axial flow Impeller (propeller) or Mixed flow type (horizontal) or vertical

| |

Single Stage Two Stage

>—i Impeller between bearings

Reversible centrifugals

Sp

Rotating Casing

Figure 2: Types of kinetic (centrifugal) pumps These pump types are not covered in this standard, and are shown here for information purposes only. Used courtesy of The Hydraulic Institute.

The simplified sketches that appear on page 7 and above describe these popular pump types, with a brief explanation of their principles of operation. The sketches are used courtesy of The Hydraulic Institute.

300.1

Gear Pumps

Gear pumps may be external or internal in design. Internal designs may have a crescent between gears. Inlet fluid fills the cavities between gear teeth and the casing. Fluid is then moved circumferentially to the outlet port, where it is discharged. Radial hydraulic forces are unbalanced, and bearings, or bushings, are required to support the rotors. Since gears touch, the materials of construction should be preferably dissimilar, especially for low-viscosity applications. Stainless steel drive gear, if running against stainless idler gear, tend to gall and should not be used, especially for low-viscosity or poorly lubricating fluids. It is better to run stainless steel drive gear against the nonmetallic (e.g. Teflon) idler gear for such applications, and this is typically done in industry.

Positive Displacement Pumps

Figure 3 and 4: External gear pump (left) and Internal gear pump (right) 300.2

Lobe Pumps

Figure 5: Lobe pump internals Lobe pumps are similar to gear pumps, except that the lobes are not in contact, and a timing mechanism is used to transfer the rotation of the drive rotor to the idler. The number of lobes varies between 1 and 5. A three-lobe design is shown above.

300.3

Multiple Screw Pumps

Figures 6 and 7: Two-screw pump (left) and Three-screw pump (right)

9

AlChE Equipment Testing Procedure These pumps are usually of the two-screw timed, or three-screw un-timed design. Inlet fluid fills the cavities between screws and the casing or liner. Fluid is moved axially to the outlet port, where it is discharged. Radial forces are unbalanced in the two-screw pump, but are balanced in the three-screw design. Technically, The Hydraulic Institute classifies Progressive Cavity pumps as a single-screw design variation. However, there is a much greater similarity between the two- and three-screw designs than between either one of them and a progressive cavity design. For this reason, a progressive cavity design is treated separately in this Procedure (see page 11).

300.4

Vane Pumps

Figure 8. Vane pump Vanes, which may be in the form of blades, buckets, rollers, or slippers, cooperate with a cam action to allow liquid to fill the cavity formed between the vane and the casing liner. The fluid is moved circumferentially to the outlet port, where it is discharged. The vane(s) can be stationary or rotating. Radial hydraulic forces may be balanced or unbalanced. Some designs provide variable flow by varying the cam action eccentricity. Illustrated above in Figure 8 is a vane-in-rotor, constant displacement, unbalanced vane pump design.

10

Positive Displacement Pumps 300.5

Progressive Cavity pumps

Figure 9. Progressive Cavity pump Progressive cavity pumps are a unique type of positive displacement pump. The simplest PC pumps have a single-threaded screw, called a rotor, turning inside a double-threaded nut called a stator. As the rotor rotates inside the stator, two cavities form at the suction end, with one cavity opening at the same rate as the other cavity is closing. The cavities progress (hence the name), from one end of the stator to the other. In most PC pumps, the stator is made with an elastomeric material (rubber, Teflon, etc.), that fits on the rotor with a compressive fit. The metallic rotor can be plated in order to increase wear resistance. This compressive fit between the rotor and stator creates seal lines where the two components contact. The seal lines keep the cavities separated as they progress through the pump. Progressive cavity pumps are known for their ability to self prime, suction lift up to 28 feet, and handle shear-sensitive and high-viscosity materials, abrasive fluids, as well as fluids with large particles in suspension.

300.6

Diaphragm Pumps

Figure 10: Diaphragm pump in operation n

AlChE Equipment Testing Procedure The Hydraulic Institute groups diaphragm pumps with controlled volume-type pumps. Hydraulically or mechanically actuated diaphragms displace the fluid from suction to discharge side and are aided by the valving mechanism, which allows fluid to enter the pump chamber during the suction stroke, and displaces it during the discharge stroke.

300.7 Piston/Plunger Pumps

Figure 11. Piston pump cross-section Piston/plunger pumps are of the reciprocating type. T h e liquid chamber is alternatively connected to the suction and discharge sides, with a system of internal valving. These pumps are particularly well suited for extremely high pressures.

12

Positive Displacement Pumps 400.0 GENERAL NOTES ON TEST PREPARATION LOGISTICS— Instruments and Methods of Measurements 400.1 Flow For positive displacement pumps, the key measured parameter is flow. For chemical plants, the most common way to measure flow is with a flow meter. Other simple methods, such as known volume vessel plus a stopwatch, or other open-end measurements, are not practical for the hazardous environment of a chemical plant. For better accuracy, flow meters should be periodically cleaned and calibrated. In theory, the viscosity of the measured fluid must be similar to the calibration fluid, but in practice there can be a wide variation of viscosity (+/- 1000 cP), and the flow measurement error would be within + / - 2%, which is acceptable for most field tests. Because the theoretical flow of positive displacement pumps is directly proportional to speed, another simple method is to measure the pump shaft rpm, and multiply it by the pump unit flow (gallons-per-revolution). The unit flow is constant for a given pump and can be calculated from the pump performance curve at zero differential pressure. The net (actual) flow is the difference between the theoretical (zero pressure differential) flow and slip. Slip can be obtained from the pump curve at a given differential pressure and fluid viscosity. In practice, for high-viscosity fluids (over 100 cP) and/or low differential pressures (less than 20 psi), the slip can be neglected and the net flow simply calculated as measured rpm times the unit flow from the curve. Note: Pump rpm can be measured using a tachometer or a strobe light. It may also be assumed, with some accuracy, to be close to the motor nameplate value, adjusted by the gearbox ratio if a gearbox is present.

It is always a good practice to conduct a pump field test soon after it has been installed, in order to generate a baseline field-specific curve for future test comparisons.

400.2

Pressure

400.3

Power and Efficiency

A common mistake is to assume the pressure at the pump inlet flange from the known pressure, such as tank level, and adjust by calculating the losses, or by assuming losses are negligible. This approach is particularly wrong for calculating the suction pressure, as collapsed filters, debris, solids, or other obstructions can make the pressure estimates completely invalid. The only reliable way is to install and read gauges and measure the pressure in suction and discharge pipes as close to the pump flanges as possible.

The most practical way to measure pump input power is to measure the motor's electric current and voltage. The available shaft power can then be calculated as: KW = I x V x ri

t

/ 1000, for 1-phase motors

13

(400.3.1)

AlChE Equipment Testing Procedure K W = I x V x 1.732 x r|

motor

x PF / 1000, for 3-phase motors

BHP = K W / 0.746

(400.3.2) (400.3.3)

The power factor and motor efficiency can normally be obtained from the motor manufacturer, at least for full load conditions. Both of these items va ry widely from motor to motor, and with changes in load on the motor. If power factor and efficiency cannot be accurately determined at the motor's operating conditions, it may not be possible to accurately determine the pump's input power. Checking that the motor current is not above the nameplaterated current at pump operating conditions may be the only possible test for input power. If there is a gear reducer, or any other device that absorbs motor output power, coupled between the motor and the pump, its power losses must be estimated. This is often available from the manufacturer. If the pump and motor are directly coupled together, motor output power can be taken as pump input power. Below are power factor multipliers recommended for three-phase Toshiba motors. For factors of particular equipment, contact the equipment manufacturer. In most cases, the power factor and motor efficiency are not readily known, and obtaining the exact values is impractical. However, as an approximation, the efficiency of the electric motor can be assumed as 95%, and the power factor is also 0.95, such that their product is approximately 0.90. As long as the performance does not change with time, such approximation would still serve a valid purpose. Finally, it is recommended the information be reviewed and confirmed, as the values for motor efficiency and power factor both seem to be the highest obtainable. These high values are usually reserved for motors in the 200 horsepower and above range. This would indicate a lower horse power motor would be required in the estimating stages than would actually be needed in operation. The key to field testing is simplicity and fully utilizing the available tools.

Table 2. Typical power factor correction table

© T.M Eiiifjson

1398

14

Positive Displacement Pumps The hydraulic (net) pump fluid power is:

FHP = (AP x Q Q / 1714) + viscous losses

(400.3.4)

The current to calculate the K W must be read at actual operating differential pressure. The overall pump efficiency is then: TI = FHP / BHP

400.4

(400.3.5)

Temperature

In the field, fluid temperature and the pump skin temperature are determined to make sure they are not excessive, and thus affecting the pump internal clearances. For certain types of pumps, especially the progressive cavity type, the internal clearances change dramatically with temperature, effecting flow slip, mechanical friction, efficiency, and pump life.

15

AlChE Equipment Testing Procedure 500.0 TESTING ROTARY PUMPS (Gear, Multiple Screw, Lobe and Vane Pumps) The objective of a test is to measure the performance of the pump under a known set of conditions. Pump performance may be defined as a group of six interrelated variables: flow through the pump (Q), power input (BHP), drive shaft speed (rpm), pressure at the suction port (ps), pressure at the discharge port (p^), and the kinematic viscosity of the liquid being pumped (v). Most of the time, flow and power are considered to be the dependent variables, and the others are independent variables. The first step in any field pump test is to decide which variables will be set, and which ones will be measured as the results. When the test is performed in the field, some of the variables will be difficult, or impossible to change from the normal values determined by the system in which the pump is installed. For example, a constant speed motor without a variable speed control cannot operate at different speeds for the test, so in this case shaft speed (rpm) would be one of the independent variables, or one of the values to be set, instead of measured. With this in mind, there are two standardized types of pump tests commonly used in factory testing that may not be suitable for field-testing conditions without some modifications. For these cases, the example test report form in Table 3 may be used to design a new test by filling in the quantities that will not be changed, or c a n n o t be changed, and measuring the other quantities. All applicable plant safety rules should be reviewed and followed whenever a facility attempts to test any rotating piece of equipment. In some cases it may be advisable to complete a plant safety review prior to attempting the test. Finally, make sure that, when the test is conducted, the operating team is, at minimum, aware of your plans and is in communication with you.

Table 3. Performance test report form (also used for the suction test, with some parameters omitted)

16

Positive Displacement Pumps 501.0

Test Equipment

Each of the variables should have an instrument to record its quantity during the test. Section 400 presents general notes on instrumentation. Even fixed variables, such as the speed of a fixed speed electric motor, should be recorded during the test to ensure that no unknown influences are introduced. For example, motor speed tends to decrease as the motor load increases, and this should be observed and recorded during the test. 501.1 Shaft Speed There are many types of tachometers that can be used on either the pump or motor shaft, as long as a device connects the two shafts and maintains a constant speed ratio between them. If a device, such as an eddy current drive, is used that varies the speed ratio between the shafts, the tachometer must be used only on the pump shaft. The tachometer should be accurate to within 2% at the test speeds. A small change in speed can make a large difference in the performance of a large, low-speed pump. A strobe light is less accurate, although it is acceptable. 501.2 Suction and Discharge Pressures Pressure gauges or transducers should be accurate to within 5% of the test pressures, and the test pressure should be between 20% and 80% of a gauge's range. Suction and discharge pressure gauges, or transducers, usually have different pressure ranges. Suction pressure is usually recorded in psia (absolute) units, and discharge pressure in psig units, (psia = psig + 14.7). 501.3 Fluid Viscosity at Range of Temperatures The simplest way to obtain an idea of viscosity during a pump test is to measure the liquid temperature and then find the viscosity from a chart of temperature versus viscosity for the test liquid. These charts are available for many liquids in reference books, as well as from the manufacturer. If no chart is available, a test with a viscometer at several different temperatures will allow you to create such a chart. The thermometer or thermocouple used to measure the temperature should be accurate to within 5% at the test temperature. If the fluid to be pumped is Newtonian, defined as having a viscosity constant with changing shear rate, it is acceptable to test a range of viscosities by using several liquids that have different viscosities at the same temperature. This is often easier than heating or cooling a single fluid to obtain a range of viscosity. Positive displacement pumps are not very sensitive to changes in liquid density or specific gravity, so one liquid can substitute for another in the test. This must not be done, however, if the liquid is non-Newtonian (thixotropic or dila17

AlChE Equipment Testing Procedure tant). If a pump is intended to operate on a non-Newtonian liquid, the test should only be performed using that liquid. Dilatant liquids, which increase in viscosity as the shear rate increases, are especially tricky because a test on a Newtonian liquid would understate the necessary input power and the pump's driver could be overloaded in operation. When a viscous fluid is involved, which is quite common with PD pumps, there are two persistent problems: establishing a reasonably accurate system curve at which the fluid will be pumped at its actual viscosity. Emphasis is placed on the "actual viscosity" that typically is a function of temperature. Start-up conditions frequently result in lower temperatures and higher viscosities than at operating temperatures, and in turn, higher horsepower than anticipated. Unless motors, pumps, and relief systems are selected appropriately this can cause a major delay in the start-up of a new system, or in conducting tests that may pass through auxiliary piping. Pump vendors have compiled technical manuals that graphically establish the relationship between pressure loss, viscosity, and pipe size. Calculations for precise values are often laborious. Consequently, estimates are frequently employed. Such methods approximate performance and do not generate a true bench test performance curve. 501.4 Flow Rate A positive displacement pump moves a fixed volume for each revolution of the drive shaft; it is volumetric flow rate, which is most closely tied to pump performance. It is possible to measure mass flow and divide by the density of the liquid. Placing a flow meter in line with the pump is the simplest method, but measuring the time to pump out or fill a tank of known volume may also be used, if possible. 501.5 Input Power In a field test it will rarely be possible to put a torque meter between the pump and driver to measure pump-input power directly. Usually, the best available option is to measure the current and voltage going into an electric motor. The power output of a three-phase AC motor can be calculated from the formulae given in Section 400.3.

502.0 Standardized Tests 502.1 Performance Test The purpose of this test is to generate graphs of flow rate versus differential (discharge minus suction) pressure, and also input power versus differential pressure, with a constant liquid viscosity, suction pressure, and shaft speed. In addition to the test equipment listed in 18

Positive Displacement Pumps Section 400, this test requires a valve near the outlet port of the pump that can be used to throttle the flow to increase the pressure at the pump. The highest pressure during the test should not be more than 90% of the opening pressure of any relief valve in the system or in the pump. Any restrictions in the system downstream of the pump should be reduced as much as possible to reach lower pressures at the pump during the test. See Figure 12 for a diagram of a typical installation and field-test setup.

Figure 12: Installation and set-up for pump performance field test Estimate the range of discharge pressures to be tested, and divide the maximum expected differential pressure by five (i.e., six points test). The result is the amount to increase the discharge pressure by the next test point. To begin, operate the pump with the throttling valve open, and record the values of all six variables. Close the discharge throttling valve slowly, and record all six variables. Record all six points in Table 3, increasing pressure incrementally. Plot the data in the form of graphs, as shown in Figure 13.

19

AlChE Equipment Testing Procedure

* If the current is measured instead, calculate and plot power using formulae in Section 400.

Figure 13: Example of pump performance curves 502.2 Minimum Required Suction Pressure Test (MRSP) This test determines the effect of changing suction pressure on pump performance. Below a certain pressure, the flow out of the pump will drop dramatically. Above this pressure, the flow asymptotically approaches the theoretical flow of the pump, as defined by The Hydraulic Institute. The suction pressure that causes the flow to drop 5% below this asymptote is considered to be the pump's minimum required suction pressure. This test requires a throttling valve in the 20

Positive Displacement Pumps suction piping near the pump, as well as another valve on the discharge side. At the beginning of the test, all valves on the discharge side of the pump should be open in order to lower the pump's discharge pressure as much as possible. The pump's supply tank should be full or, if it is portable, raised as high above the pump as possible. This will increase the pressure at the pump's suction as much as possible, so that during the test, the flow will be as close as possible to the theoretical ( Q J when the suction valve is open. Figure 14 shows the test setup, and Figure 15 shows the outcome of the test in a graph of flow versus suction pressure. The same table (Table 3) can be used with only suction pressure and the flow recorded, or other parameters of interest can be noted as well. During this test, shaft speed, discharge pressure, and liquid viscosity are held constant. Input power does not change too much, and it is usually not measured for this test.

Vent Tank Overflow Discharge Tank

■©■ «

Flow Meter Relief Valve

Motor

If*

Tachometer

ps

£ y$-

f4Throttling Valve

Supply Tank

Throttling Valve Pump

testing for p .illlin>

Figure 14: Minimum suction pressure test set-up Operate the pump with both throttling valves open, and record the values of all of the variables. Start slowly, closing the suction sidethrottling valve until the suction pressure drops 2 psi below its previous value. Record the values of all the variables again. Repeat this process using increments of 2 psi in the suction pressure until the pump's flow has dropped to 90% of what it was at the beginning of 21

AlChE Equipment Testing Procedure the test. Do not operate the pump in this condition for any longer than is necessary to record the data, and never close the suction side valve all the way while the pump is running. Plot the flow at the various pressures recorded for this test in Table 3, in the form of the graph in Figure 15. Note: If increased noise or vibrations are encountered, do not operate beyond that point. Minimum required suction pressure, in this case, would be determined not by the 5% flow decrease rule, but by the mechanical and structural limitations of the pump oryour system. Discuss these results with the pump manufacturer. If the minimum required suction pressure determined is significantly different from the manufacturer's catalog value, pump and/or system troubleshooting might be advis able.

Figure 15: Minimum suction pressure results 503.0 Other Tests There are many other tests that may be performed on pumps other than the two described above. The three most common are sound pressure level, vibration, and temperature measurements.

22

Positive Displacement Pumps 503.1 Sound Pressure Level Sound pressure level measurements may be taken at the pump's normal operating condition, or may be made in conjunction with one of the performance tests above to give a record of sound pressure levels across a wide range of conditions. The microphone locations for the test should be approximately 5 feet above the floor or walkway nearest the pump. One reading should be taken from each end of the pump and motor set, approximately 3 feet away from the pump or motor housing. Other readings should be taken at the pump's inlet and discharge ports and on both sides of the motor. All of these readings are taken 5 feet above the floor. If the pump and motor are mounted vertically, take a reading at four positions, 90 degrees apart, around the pump. These should all be taken 5 feet above the floor, and 3 feet away from the nearest part of the pump or motor housing. Note that the environment around the pump, such as acoustically reflective or absorbent surfaces, can have a great influence on the sound pressure measured value. Other equipment operating nearby will also influence sound pressure measurements. 503.2 Vibrations and Temperature Vibration and temperature measurements are usually taken for maintenance reasons, and can be used to predict an upcoming failure so the problem can be corrected before it occurs. To do this, it is very important to take baseline measurements before any problems occur. Then changes in these quantities (with time) can signal an upcoming problem. Vibration and temperature measurements are normally taken at a pump's normal operating condition. The key parts of the pump that affect its reliability must be determined, and the measurements taken as close as possible to these components. Measurements are usually taken on the surface of the pump housing; instrumentation can be put inside the pump before installation to monitor particularly critical components. The most commonly monitored components are bearings, rotors, and shaft seals. Table 4 can be used to detect changes by recording pump parameter trends with time. However, the basic parameters, such as speed, operating pressure, pumped liquid, and so forth, must remain the same, in order to obtain a valid comparison of the parameters that are truly changing with time.

504.0 Test Process Example Figure 16 is an illustration of a rotary gear pump installed at a chemical plant on an acid transfer application. A magnetic flow meter was present further downstream, past the check valve. It was equipped with an electronic data port and connected to the plant

23

AlChE Equipment Testing Procedure Table 4: Time trending of basic parameters

control room, where operators could read the pump flow directly. There was a gearbox between the motor and a pump, with a resultant pump speed of 1000 rpm. The pump took suction from the vented tank, but with a slightly pressurized nitrogen blanket, about 10 psig. The maximum discharge pressure was below 80 psig. The normal rated operating point was 20 gpm at 50 psig discharge pressure, although a pump manufacturer catalog allowed pump maximum differential pressure to 100 psig at the given fluid viscosity and pump speed. Unfortunately, there were no pressure gauges installed near the pump. Gauges had to be added near the existing vent/drain connections. This was considered sufficiently close to the pump inlet and discharge flanges. Shaft speed was monitored by a handheld tachometer reading the signal from the translucent reflective tape mounted near the coupling. Motor current was monitored from the operator's console in the control room. Fluid viscosity (approximately 40 cP) was measured at the ambient temperature of 80 °F before the test. Specific gravity could not be measured, but was assumed to be 1.2, per the pump datasheet. 504.1 Performance Test In accordance with a six-point test procedure, described in section 502, the incremental pressure steps were approximately established as:

(504.1.1)

During the test these increments were actually held between 15 and 20 psi.

24

Positive Displacement Pumps

Figure 16. Sample installation for a rotary pump test The operating personnel were notified that the test was about to start. Discharge and suction valves were opened. It was verified that the pump suction was flooded. The pump was started and operated for about 10 minutes to stabilize the process. Air was purged from the system and the instruments. The discharge valve was throttled slowly and the data were recorded in the following table.

25

AlChE Equipment Testing Procedure Table 5: Raw performance data for rotary pump test Speed

Test Point

#

rpm 1003 1001 998 998 995 997

1 2 3 4 5 6

Suction Pressure psia 22 22 21 22 21 22

Discharge Pressure psig 9 20 37 57 74 94

Flow QPm 23.7 23.5 22.5 22 21.7 20.8

Current Temperature Amps 0.7 0.8 1.7 2 3.1 3.5

Comments

78 78 78 78 79 79

For the three-phase 3 Hp electric motor, rated at 440V, the horsepower was calculated as: KW = I x V x 1.732 x PF x E F F m o t o r /1000 Voltage at the motor leads was measured as 465V This did not change significantly during the test. The power factor times the motor efficiency was assumed to be 0.9, because the motor performance curve was not available. BHP = K W x 0.746 = I x (465 x 1.732 x 0.9 x 0.746 / 1000) = I x 0.54. The results of the test, listed in Table 6, were then plotted. The resultant performance curve, shown in Figure 17, was compared with the manufacturer's catalog curve (Figure 18) and determined to be within close agreement.

Table 6: Calculated parameters for performance test Test Point #

1 2 3 4 5 6

Delta P (Pd - Ps) psia 1.7 12.7 30.7 49.7 67.7 86.7

Flow

Bhp

gpm 23.7 23.5 22.5 22.0 21.7 20.8

0.40 0.45 0.94 1.10 1.70 1.90

Comments

Note: A manufacturer's catalog may not always have the curves at the exact viscosity, and some interpola tion may be required. In this example, the test curvesfor the 40 cPfluid correlate reasonably between the published curves for 1 cP and 200 cP, as shown in Figure 18. 26

Positive Displacement Pumps

Figure 17: Performance curve drawn from data in Table 6 504.2 Observations: 1) The pump performed as expected. At the normal operating point, there was sufficient flow (20.5 gpm). This was slightly above the required 20 gpm. Qgj- = 23.7-20.5 is approximately 3 gpm. 2) No abnormal noises or vibrations were observed. 3) There was no problem with the motor. Amperage readings throughout the test did not exceed the motor's nameplate full-load amps. In addition, observations did not detect excessive motor temperature rise, which would have been an indication of overload. At the maximum operating pressure (80 psig), the pump requires 1.8 hp, which is below the motor nameplate rating of 3 hp. An oversized motor had been selected in anticipation of future applications for heavier liquids. 4) It is usually not a practice to calculate efficiencies for PD pumps, but, if desired, the calculation would be as follows:

Volumetric efficiency at the rated point:

27

AlChE Equipment Testing Procedure Overall efficiency at the rated point:

Figure 18: Performance comparison to the manufacturer's catalog curve

28

Positive Displacement Pumps 504.3 Minimum Required Suction Pressure Test The pump was operated again with open discharge and suction valves and allowed to stabilize for five minutes. The suction valve was then slowly closed, and data were recorded at different pressure points. See Table 7 for results. The test was started at 4 psi intervals, and increments of pressure were reduced as the flow started to decrease. Test Point

Pressure (Ps)

Flow

Comments

#

psia

qpm

1 2 3 4 5 6 7 8 9 10 11

22 18 15 12 10 8 6 5 4 3 2

23.5

Start up of the test

23.5

Estimated 5% loss @ 22.3 gpm

23.5 23.4 23.3 23.2 23.1

Cavitation "crackling" has started

23.0

Cavrtation more intense at this point

22.8 22.4

Near Ps min (5% flow drop at this point) Beyond 5%, sever, loud noise experienced:

-

21.4 -

-

-

The pump should not be kept at this operating condition for long Return to normal operating condition by opening the suction valve.

Table 7: Minimum required suction pressure test (Field data) The results from Table 7 were then plotted in Figure 19.

29

AlChE Equipment Testing Procedure

Figure 19: Minimum required suction pressure test graph For data in Table 7

504.4 Observations: 1. Minimum required suction pressure for cavitation-free operation is P'suction = 2.-7 psia at 1000 rpm and 40 cP. 2. Some cavitation "crackling" noise was observed at approximately 6 psia. Since the installation had plenty of available suction pressure, about 22 psia (7.3 psig), the pump should not experience future cavitation problems. 3. The results are applicable only to the given pump, operating at the given speed and pumping similar viscosity material. At other speeds or viscosities, the value of the minimum required suction pressure would be different and would need to be established by performing a test procedure similar to that outlined above. 504.5 Other Tests Sound, vibrations, or other parameters were not recorded in these tests, but could be easily accommodated if required. Such extended tests are usually performed to troubleshoot a pump/system to pinpoint internal problems, such as mechanical rub, cavitation, or failing bearings, which can be determined by using a frequency analysis.

30

Positive Displacement Pumps 600.0 Progressive Cavity Pump Testing Progressive cavity pumps are a unique type of rotary positive displacement pump. The simplest form of a progressive cavity pump is a single-threaded helical rotor turning inside a double-threaded helical stator. In most progressive cavity pumps the stator is made with an elastomeric material and fits on the rotor with a compressive fit. The contact between the rotor and stator creates a seal that results in the formation of cavities. The geometry of the parts is such that, as the rotor turns through one complete rotation, two cavities are formed. One cavity closes at the same rate as the second cavity opens, progressing from the suction to the discharge end of the stator, thus giving it the name "progressive cavity pumps." Progressive cavity pumps can generally be tested in the field in accordance with the procedures outlined in Section 400. However, due to the wide range of functions for which progressive cavity pumps can be applied, the unique characteristics of the pumped fluid must be considered. In many applications, pump testing is performed with water and the results achieved with water must be correlated to the actual process fluid. Precautions: Before operating progressive cavity pumps, it is essential that the system be reviewed to ensure that the suction and discharge lines to the pump are not obstructed. Progressive cavity pumps cannot operate dry or withoutfluid passing through them for prolonged periods of time without damaging the pump. Similarly, progressive cavity pumps cannot be operated against a closed or obstructed discharge line without possible damage to the pump and system, and possible injury to personnel.

The pressure capability of progressive cavity pumps is a function of the number of stages, pump size, pump speed, and fluid pumped. It is recommended that the operating characteristics of the particular pump model be known before operating the pump.

601.0

Test Equipment

The instrumentation described in paragraph 500.0 (Test Equipment) is generally acceptable for use with progressive cavity pumps, with some additional consideration given to the unique characteristics and capabilities of this pump design. 601.1 Shaft Speed Progressive cavity pumps typically operate at slower speeds than other types of pumps. Although the use of mechanical shaft speed indicators is preferred, properly calibrated strobe tachometers are also acceptable. In many applications, a speed indicator is included as part of the drive package and, when properly calibrated, are acceptable for accurately determining shaft speed.

31

AlChE Equipment Testing Procedure 601.2 Pressure Instrumentation Since progressive cavity pumps are often used for pumping viscous and solids-laden fluids, suitable isolation devices must be used with the pressure measuring equipment to avoid plugging of the stem to the pressure gauge or transducer. Suitable isolation devices have an elastomeric or other pliable membrane in contact with the pumped fluid. A reservoir behind the pliable member is filled with a suitable sensing fluid and the pressure measuring device is threaded into a port in direct contact with the fluid reservoir. Preferred devices will not obstruct the fluid flow. If NPSH tests are to be performed, a compound gauge or transducer must be used on the suction of the pump to permit both positive and negative pressures to be read. 601.3 Fluid Viscosity The actual viscosity of a fluid as it passes through a progressive cavity pump can have a significant effect on volumetric efficiency and required shaft horsepower. Since most viscous fluids pumped by progressive cavity pumps are non-Newtonian, the actual fluid viscosity in the pump and in the piping systems will depend on the shear rate. Therefore, viscosity measurement instruments, which enable a plot of viscosity vs. shear rate to be developed, are essential. In reality, proper sizing and selection of a progressive cavity pump requires some knowledge of fluid viscosity. Some pump manufacturers evaluate a potential customer's fluid and perform viscosity tests prior to selling them a pump. If this data is available, then testing the fluid viscosity in the field would serve to verify the rheological properties of the fluid, but would otherwise be of little value. If the viscosity of the fluid was not evaluated prior to the test, then viscosity measurement instrumentation, which enables determination of the viscosity of the fluid at various shear rates, is essential. If the pump is to be tested with water but will eventually pump a viscous fluid or slurry, the pump manufacturer should provide documentation supporting that any conclusions drawn from the water test could be extrapolated to expected performance with the actual process fluid. 601.4 Flow Measurement Progressive cavity pumps are rated in terms of theoretical displacement per revolution. As the discharge pressure increases, the actual output may be somewhat less than the theoretical displacement per revolution times the shaft speed. This reduction in flow is due to internal leakage, or "slip." Therefore, using the shaft speed and theo32

Positive Displacement Pumps retical displacement to determine flow rate is not recommended at discharge pressures in excess of 15% of the rated pressure limit of the pump. A calibrated flow meter compatible with the process fluid, or recording the time it takes to fill or empty a tank of known volume, are recommended for determining the flow rate at the specified design point or across the range of operating pressures. 601.5 Input Power Determining the pump input power for a progressive cavity pump in the field is difficult. The power output of a three-phase AC motor can be calculated from the formulas given in Section 400. However, most progressive cavity pumps are not driven at synchronous motor speeds, so speed reduction devices, such as gear reducers or belts and pulleys, must be used to reduce the speed. Speed reduction device specifications must be consulted to determine the efficiency of the reduction device used in order to arrive at the pump-input power. It is also common practice to use variable frequency drive (VFD) packages for progressive cavity pumps. Many of the newer drives provide readouts of the power to the driven equipment. The drive manufacturer should be consulted for the accuracy of data obtained from the readouts. O n a larger VFD it is possible to record the current and voltage into the drive and obtain reasonably accurate power values using the appropriate formulae. On smaller drives (approximately 10 HP and smaller), the accuracy of obtaining readings this way is questionable, and the drive manufacturer should be consulted.

602.0

Tests

The following tests are generally applicable to progressive cavity pumps as long as certain characteristics of this type of pump are recognized. One is that the performance of progressive cavity pumps is affected by fluid temperature. Factory performance tests are typically performed with water at 20° C. Temperature changes affect both fluid viscosity and pump clearances. As temperature increases, clearances and viscosity decrease and these changes compete to determine the effect on slip, Therefore, if the pump is to be tested with a fluid at a temperature or viscosity different than originally specified, the pump manufacturer should be contacted for help in correlating the test results. Progressive cavity pumps recommended for use when pumping fluids at temperatures in excess of 70° C are typically assembled with undersized rotors. This is necessary to accommodate the significant thermal expansion of the stator elastomer and prevent excessive compression between the rotor and stator. If the pump is to be tested with a fluid that is not at the same temperature as the process fluid, performance may not meet the specified flow rate at the specified pressure. The pump manufacturer must be contacted to correlate recorded performance results to the specified operating conditions. 33

AlChE Equipment Testing Procedure Progressive cavity pumps intended for highly viscous fluids, but tested on water or a similar low viscosity fluid, may produce performance test results that do not correspond to the specified operating conditions. The pump manufacturer should be contacted for assistance in correlating the test results to the specified process conditions. 602.1 Performance Tests Performance tests can be carried out in accordance with the procedures described in 502.1. 602.2 NPSHTest The minimum suction pressure test (NPSH) can generally be performed as described in paragraph 502.2. However, the unique characteristics of progressive cavity pumps permit them to be used in low suction pressure applications where the flow rate is considerably below the 5% reduction in flow defined by The Hydraulic Institute. Therefore, the test described in paragraph 502.2 may be continued until the onset of clearly audible noise from the pump, until the pressures become erratic, or until there is no flow from the pump, whichever occurs first. In performing tests where a valve is slowly closed to create a restriction in the suction and or discharge lines, it is possible that the nearly closed valve will create cavitation across the valve, and will often be quite audible. The noise originating from the valve should not be confused with noise related to pump cavitation. Whenever possible and affordable, pumps should be bench tested at the factory to avoid NPSH problems during start-up. Correcting NPSH problems after installation can be expensive and impractical.

603.0

Other Tests

603.1 Sound Pressure Level For most applications and operating conditions the sound pressure level of progressive cavity pumps is less than the driver sound pressure level. Therefore, determining background sound pressure levels before operating the pump is extremely important for obtaining accurate readings. The procedures outlined in paragraph 503.1 are appropriate for use with progressive cavity pumps. 603.2 Vibration Measurements Rotors in progressive cavity pumps rotate eccentrically within the stator. This results in unbalanced forces, which are generally absorbed by the rigid supports and mounting structures typically used with progressive cavity pumps. However, these forces can affect readings taken on the bearings, reducers, and other components. Therefore, if vibration readings are to be used for predicting maintenance intervals, it is important to make accurate baseline measurements before and during pump operation. 34

Positive Displacement Pumps 603.3 Temperature Measurements Temperature measurements are generally of limited use in determining appropriate maintenance intervals for progressive cavity pumps. However, if temperature is to be used as a possible indicator of required maintenance, baseline readings should be taken after the pump has been in normal operation for a minimum of 100 hours. Certain components of PC pumps, such as the bearings and universal joints, may operate at slightly elevated temperatures until the lubrication is evenly distributed and the components are seated. 603.4. Miscellaneous As with all new or different equipment, the manufacturer should be contacted if there are any doubts or questions about its safe and proper operation. This is especially true of positive displacement pumps, since many are capable of developing high pressures and require safety protection to avoid equipment failure and possible injury to personnel.

35

AlChE Equipment Testing Procedure 700.0 Air-Operated Diaphragm Pumps The objective of diaphragm pump testing is to measure the performance of a pump under a known set of conditions. Pump performance may, in turn, be defined by a group of inter-related variables, including liquid flow rate, the air inlet pressure, the liquid inlet pressure, the liquid discharge pressure, and the kinematic viscosity of the fluid being pumped. When conducting a test involving head pressure, the total dynamic head (TDH) needs to be used. The T D H is the difference of the total discharge head and the total suction head. Typically, flow and air consumption are considered dependent variables, and the others are considered independent variables. However, sometimes the flow is held constant and the resulting air inlet and T D H pressures are recorded. Note that these tests are commonly used for factory testing, but field conditions may not be suitable for performing these tests without modifications.

700.1

Recommended Installation

There are four factors that need to be addressed when installing an air-operated double diaphragm pump. These factors are listed in the following sections.

700.2

Access

700.3

Air Supply

Convenient access to the test pump is very important. If there is adequate access to the test pump, technicians will have an easier time performing tests and routine inspections. Ease of access can play a key role in speeding up the testing process. Every pump location should have an air line large enough to supply the volume of air necessary to achieve the desired pumping rate. Use air pressure up to 125 psi (8.6 bar) depending on pumping requirements. For best results, pumps should use a 5 micron air filter and an air pressure regulator. Using an air filter before the pump will ensure that the majority of any pipeline contaminants will be eliminated.

700.4

Elevation

Selecting a site that is within the pump's dynamic lift capability will ensure that loss of prime troubles will be eliminated.

700.5

Flexible Connections

Due to the natural reciprocating nature of the pump, it is recommended that flexible connections be used at the inlet, discharge, and air inlet of the pump. Flexible connections between the pump and rigid piping will help to reduce the vibration of the pump. The best installation location will be a site involving the shortest and straightest hook-up of suction and discharge piping. Unnecessary bends, elbows, and fittings should be avoided to keep friction losses to a minimum. In addition, the piping should be configured so that it does not put any additional stress on the pump connections. A typical set up of a test pump is shown in Figure 20. 36

Positive Displacement Pumps Air-operated diaphragm pumps can handle a wide variety of liquids. The manufacturer should always be consulted about the chemical compatibility of the test pump components and the instruments used in the test.

Figure 20. Typical installation of a test pump 701.0

Test Equipment

Each of the twelve variables should have an instrument to record quantities during the test. Fixed variables should always be measured and recorded to ensure that unknown influences are not introduced. 701.1 Inlet Air Pressure (psi, kPa) Inlet air pressure is typically varied for different tests through the use of a pressure regulator placed on the inlet air line of the pump. Pressure gauges and transducers should be accurate to within + 5%, and the test pressures should be within 20% and 8 0 % of the gauge range. 701.2 Fluid Discharge Pressure (psi, kPa) The discharge pressure can be controlled through the use of a valve placed in the discharge piping of the pump. Pressure gauges and transducers should be placed between the valve and the discharge of 37

AlChE Equipment Testing Procedure the pump. Pressure gauges and transducers should be accurate to within ± 5 % , and the test pressures should be within 20% and 80% of the gauge range. Discharge pressure is usually recorded in psig (gauge) units (psig =psia + 14.7). 701.3 Fluid Inlet Pressure (in Hg, kPa) The liquid inlet pressure can be controlled through the use of a valve placed in the inlet piping of the pump. Pressure gauges and transducers should be placed between the ball valves and the inlet of the pump. Pressure gauges and transducers should be accurate to within ± 5%, and the test pressures should be within 20% and 80% of the gauge range. Suction pressure is usually recorded in psia (absolute) units. 701.4 Process Fluid Temperature (°F, °C) Process fluid temperature should be measured and recorded several times during the test. The thermometer or thermocouple should be accurate to within + 5%, and the fluid pressure should be within 20% and 80% of the gauge range. Record the process fluid temperature on the Field Test Data Sheet in Table 8. 701.5 Environment and Inlet Air Temperature (°F, °C) Environment and inlet air temperatures should be measured during the test. The inlet air temperature reading should be taken as close to the pump inlet as possible. This is typically done through the use of a thermometer placed in the air line just before the pressure regulator. The environment temperature readings should be taken in the same area as the test pump location. The thermometers or thermocouples should be accurate to within ± 5 % , and the air temperature should be within 20% and 80% of the gauge range. Record environmental and inlet air temperatures in the Field Test Data Sheet in Table 8. 701.6 Viscosity (SSU, centipoise) The simplest way to determine the viscosity of a liquid is to measure the liquid temperature, then find the viscosity from a temperature vs. viscosity table for that liquid. These tables are available from the manufacturer or in reference books. If no table is available, one may be created using a viscometer to measure the liquid at various temperatures. The thermometer or thermocouple should be accurate to within ± 5% and the air temperature should be within 20% and 80% of the gauge range. Record the viscosity in the Test Data Sheet in Table 8.

38

Positive Displacement Pumps 701.7 Specific Gravity The simplest way to determine the specific gravity of a liquid is to measure the liquid temperature, then find the specific gravity from a temperature vs. specific gravity table for that liquid. These tables are available from the manufacturer or in reference books. The thermometer or thermocouple should be accurate to within ± 5°/0, and the air temperature should be within 20% and 80% of the gauge range. Record the specific gravity in the Field Test Data Sheet in Table 8. 701.8 Ambient and Inlet Air Relative Humidity (%) The simplest way to measure the ambient relative humidity is to use a relative humidity sensor or a sling psychrometer. If a sensor is not available, then ambient relative humidity can be calculated by measuring the wet and dry bulb temperatures to determine the relative humidity. The inlet air relative humidity reading should be taken as close to the inlet of the compressor as possible, and the ambient relative humidity readings in the same area as the test pump location. Record the ambient and inlet air relative humidity on the Test Data Sheet in Table 8. 701.9 Air Consumption (SCFM) The best way to measure the amount of air used by the pump is by an air consumption meter. The meter should be placed in the air inlet line between the compressor tank and the pump inlet. If a reading is taken in ACFM (actual cubic feet per minute), then it should be converted to SCFM (standard cubic feet per minute). SCFM is the standard of measurement used by the American Society of Mechanical Engineers and the Compressed Air & Gas Institute, and is the reading taken at 14.7 psia, 68° F, and 36% relative humidity. The meter should be accurate to ± 5% and the measurement should be within 20% and 80% of the meter range. 701.10 Flow (GPM, m 3 /hr) A flow meter installed in the discharge line of the pump is the simplest method for measuring flow. Alternatively, flow can be determined by measuring the amount of time it takes to fill a tank of known volume. The flow meter should be installed downstream from the pump with a minimum of 10 pipe diameters of straight pipe between itself and any fittings or flow restrictions, such as a discharge valve. The flow meter should be accurate within + 5 % , and the measurement should be within 20% and 80% of the meter range.

39

AlChE Equipment Testing Procedure Table 8. Datasheet for field test of an air-operated diaphragm pump

701.11 Sound (dBA) Sound measurements should be taken using a sound level meter with an octave band filter. Both meter and filter must meet ANSI S1.41983, and IEC-651 Type 2 codes. The measurement should be within 20% and 80% of the meter range.

40

Positive Displacement Pumps 701.12 Blow-by (ft/m, m/s) Blow-by measurements should be taken using an air velocity meter, accurate to ± 5%, and the measurement should be within 20% and 80% of the meter range.

702.0

Tests

702.1 Performance Test To test the general performance of the pump, the following tests should be performed. 702.1.1 FLOW: The purpose of this test is to determine the amount of liquid the test pump will deliver over a certain period of time, data which is then used to create the flow curves for the pump. Required equipment: flow meter, pressure gauges at the air inlet and the discharge of the pump, pressure regulator, intake and discharge valves, SCFM meter. To conduct this test, the air inlet pressure should be set to 20 psig and the discharge head should be set to 0 psig. The pump is then run for 1 minute and the air use and the flow rate are recorded. The discharge head pressure is increased using the discharge valve, and the procedure is repeated for the various air inlet and discharge head pressures listed in Table 9. The results for this test are recorded in the Flow Test Data Sheet in Table 9. 702.1.2 START-UP PRESSURE: The purpose of this test is to determine the amount of air pressure needed to initiate operation of the pump in the test application. Required equipment: pressure regulator, and a gauge on the air inlet of the pump. To conduct this test, first set the pressure regulator so there is no air entering the pump. Next, adjust the regulator slowly to release air to the pump and continue until the pump begins to operate. This procedure should be repeated three times, and average pressure at which the pump begins to run should be recorded. Start-up pressure is recorded in the test data sheet shown in Table 8.

41

AlChE Equipment Testing Procedure Table 9. Flow test datasheet showing startup pressure Flow Test

702.1.3 STALL PRESSURE: The purpose of this test is to determine the minimal amount of air pressure needed to keep a pump running in the test application. Required equipment: pressure regulator, and a gauge on the air inlet of the pump. 42

Positive Displacement Pumps Table 10. Test inspection log for life test

To conduct this test, the pressure is slowly reduced to a running pump through the use of the pressure regulator until the pump no longer operates. This procedure should be repeated three times, and average pressure at which the pump stops running should be recorded in the Field Test Datasheet in Table 8. 43

AlChE Equipment Testing Procedure 702.2 Life Test A life test is used to gather information on product wear and/or performance. Required equipment: no additional equipment are needed for this test. To perform this test, the pump is operated under normal conditions for the test location until a wear part (diaphragm, ball, etc.) fails, or for a specified amount of time. The pump is visually inspected periodically and the results are recorded in Table 10.

703.0

Other Tests

The following are optional tests users may want to conduct, but are not required. 703.1 Blow-by This test is performed to measure the amount of air that passes through the air valve/center section and out the exhaust at 100-psig air inlet pressure when the discharge valve is closed. Required equipment: pressure regulator, gauge on the air inlet line of the pump, discharge valve, air velocity meter. To perform this test, operate the pump at 100-psig line inlet pressure and close the discharge valve. Place an air velocity meter at the exhaust and measure the velocity of the air passing by. Results are recorded, then the process is repeated with the discharge valve opened slightly to allow the pump to shift once. The results are recorded in Table 8. 703.2 Dry Vacuum The dry vacuum test is performed to determine the maximum dry vacuum the pump will draw. For this test the pumping medium is air. Required equipment: vacuum gauge installed between the inlet valve and the liquid inlet of the pump. To begin this test, disconnect the inlet of the pump from the pumping medium, operate the pump at 10-psi inlet air pressure, close the ball valve on the inlet fixture, and record the vacuum reading in Table 11. Open the ball valve slowly to let the pump return to normal cycle. A total of three vacuum readings should be taken at each inlet air pressure setting, and should be adjusted in 10-psi inlet air increments up to 100 psig. The results are recorded in the Vacuum Test Datasheet in Table 11. 44

Positive Displacement Pumps Table 11. Vacuum test datasheet

703.3 Wet Vacuum This test is performed to determine the maximum wet vacuum the pump can draw. For this test the pumping medium is the process fluid. Required equipment: a vacuum gauge installed between the inlet valve and the liquid inlet of the pump. To begin this test, operate the pump at 10-psi inlet air pressure and close the ball valve on the inlet fixture. Record the vacuum reading in Table 11. Open the ball valve slowly to let the pump return to normal cycle. A total of three vacuum readings should be taken at each inlet air setting, and the inlet air should be adjusted in 10-psi inlet air increments, up to 100 psig. Results are recorded in the Vacuum Test Datasheet in Table 11. 45

AlChE Equipment Testing Procedure 703.4 Sound Test (100/0) Sound tests conducted at 100-psig inlet and 0-psig head are used to quickly evaluate a product's sound emissions in the "A' band. Required equipment: pressure regulator, a gauge on the air inlet line of the pump, and a sound level meter with an octave band filter. Ideally, the test should be performed in an area free from extraneous sound. All other equipment in the testing area must be off. The procedure for obtaining sound emissions is based on OSHA Noise Exposure Standard 1975. Results are recorded in Table 12.

Table 12. Sound test datasheet

704.0

Field Test Process Example

An example of a pump test installation in a water transfer application is shown in Figure 21 on the next page. A flow meter was installed downstream from the discharge ball valve so the flows did not have to be measured using a scale. Gauges were installed in the air inlet, just before the suction manifold, and just after the discharge manifold. The estimated ideal operating point was at an air inlet pressure around 70- and 30-psi discharge head. The target flow rate was at least 20 GPM. Air consumption was measured with an air consumption meter. Fluid viscosity was measured at an ambient temperature of 80° F before the test, and was found to be 31.5 SSU's. The specific gravity of water is 1. Relative humidity readings were taken using a sensor at both the inlets of the compressor, and in the area of the test pump. The relative humidity of the test area and the inlet air were 65% and 70%, respectively. These readings were all recorded in Table 13.

46

Positive Displacement Pumps

Figure 21. Typical installation of a pump test system 704.1 Performance Test Flow Test: For this test, the air inlet pressure was set to 40 psi and the discharge valve was completely open. The T D H for this test was calculated to be approximately 22 psi; therefore, no readings for the flow test could be taken at head pressures lower than 30 psi. The pump was first operated at 40-psi air inlet and 30-psi discharge. Readings were taken from the flow and air meters and recorded in Table 14. The process was repeated for all of the applicable inlet air and discharge head pressures, and the results were plotted in Figure 22. 704.2 Observation: The pump performed as expected. At normal operating pressures— 70-psi inlet air pressure and 30 psi discharge pressure—the pump had a flow of 31.7 GPM, which is well above the required 20 GPM.

47

AlChE Equipment Testing Procedure Table 13. Example of a field test datasheet for an air-operated diaphragm pump in a water transfer application

These results are applicable for the liquid pumped during this test. Using other liquids would change the viscosities and results would need to be re-established through similar testing.

48

Positive Displacement Pumps Table 14. Data from a sample flow test

AlChE Equipment Testing Procedure

Figure 22. Sample flow curve

Positive Displacement Pumps 800.0 RECIPROCATING POSITIVE DISPLACEMENT PUMP (RPDP) TESTING This section covers the testing of piston and plunger pumps, although many of the considerations are similar to diaphragm pumps operated by a reciprocating mechanism. In a pis ton pump, the seal moves with the piston. In a plunger pump, the plunger moves within a stationary seal. Although they are used for pressures as low as 100 psi, they are typically known to operate at high pressures, from 300 psi to 15,000 psig. The major advantage of modern piston, and especially plunger, pumps is that they are virtually slip-free, so that the flow is independent of pressure. Volumetric efficiency is reduced at very high pressures due to compression of the metal surrounding the plunger (the plunger cavity/cylinder increases in volume) or when liquid compressibility starts to become significant. For practical purposes, compressibility up to 8,000 psig for liquids such as water can be ignored. With more compressible liquids, such as liquid COo, compressibility comes into play much earlier. Piston pumps are generally limited to operating at less than 1,500 psig because of the limited support offered to the seal.

800.1

Safety Precautions

When these pumps are tested, it is important to remember that they move discrete volumes of liquid. These volumes are defined by the displacement of the piston or plunger, are cut off from the inlet feed when the inlet valve closes, and are discharged when the cylinder pressure exceeds the pressure on the discharge side. There is no going back! So, be careful not to dead-end the pump during test. The liquid has to go somewhere or something else has to give. Therefore, it is essential to first ensure that there is a safety valve fitted on the discharge side of the pump. Any system changes necessary for the tests must be installed after the safety valve.

800.2

Piping

There are two phenomena with RPDPs that affect the piping, and these should be given consideration over and above the general piping requirements provided in Appendix C, paragraph 900.3. There is torque about an axis perpendicular to the crankshaft, and at its center. As one side plunger is under pressure, it is pushing back on the crankshaft, trying to twist it. As the crankshaft rotates and the opposite side plunger comes under load, it tries to twist the crankshaft the other way. For a horizontal pump, this creates a side-to-side rocking movement at the pump head of very small magnitude. However, if there is a long, rigid pipe attached to the head, what might be a very small movement at the head can become very large at the other end of the pipe. It is therefore very good practice to install flexible links 51

AlChE Equipment Testing Procedure in both inlet and discharge lines, close to the pump. As discharge pressures are usually high, high-pressure hose can be relatively stiff, especially under pressure. If space is tight, use a loop of hose to isolate the movement. As individual cylinders operate, there is a discrete forcing frequency to the flow. If there is a resonant length of pipe in the system, this can lead to noise and/or damage to the piping, especially on the discharge side. On the inlet side, design care should be taken to review the requirement to accelerate the liquid into the cylinders as well as the bubble point of the fluid being handled. The supplier should be consulted for proper design considerations.

800.3

Test Objective

The objective of the test is to measure pump performance at the operating point or over its range of operating points. The principal values that need to be measured are flow through the pump (Q), pump shaft speed (rpm), pressure at the discharge port (p^), and pressure at the inlet port (ps). Pressures can vary with time: maximum discharge pressure, as well as its average, should be recorded. A whole duty cycle should be examined as the actuation of system valves can cause pressure spikes. For the inlet pressure, both maximum and minimum are required in order to establish how well the pump is running, preferably as a pressure trace versus time that would allow subsequent frequency analysis. The viscosity and density of the liquid have less influence on the power absorbed by the pump than with other designs. Providing a full charge of liquid can enter the cylinder on demand (i.e., sufficient NPSHA), viscosity has little effect on flow. Unless these pumps run very slow (less than 100 rpm) and at low discharge pressures (less than 300 psi), the pumps have a very high efficiency (over 80%). Therefore, it is only necessary to check that the motor draws no more than its rated current at the rated voltage. Voltage and current values can be used to calculate the power absorbed if it is required.

Table 15. Data collection table for reciprocating pump test Data Collection Date:

Site:

Liquid:

Max liquid Temp F/C:

Speed RPM

Flow Average discharge US gpm Pressure-psi(g)

T e s t e d by: Vp @ Max Temp:

Specific Gravity:

Psl(a)

Viscosity: centipoise (cP)

Maximum discharge Maximum inlet Pressure - psi (g) Pressure- psi (a)

52

Minimum inlet Drawn Pressure" - psi(a)HP:

Positive Displacement Pumps 801.0 Test Equipment Any instruments to be used in testing should have been recently calibrated. Instrument accuracy is often quoted as a percentage of full-scale reading. A 2000-psi gauge with a ± 2% accuracy will measure to ± 40 psi. That is a ± 4 % accuracy for a measurement of 1000 psi. The same accuracy on a 5000-psi gauge is ± 100 psi to give ± 10% accuracy at 1000 psi. Gauges used should be properly sized for tested range. 801.1 Shaft Speed Shaft speed should be measured by a tachometer, as with other PD pumps. If it is acceptable that the flow rate can be ± 5%, then the tachometer needs to measure to + 2 % at the test speeds. Use of calibration charts is recommended. The measured value should be recorded, the correction from the chart logged, and the corrected figure calculated. This is best achieved when the tachometer has a digital readout. The column for shaft speed data in Table 1 could be expanded to add:

Measured rpm

Correction Arpm

True rpm

801.2 Suction Pressure It is important to keep the liquid well away from forming vapor. This is why absolute gauges are preferred (psia) to avoid dealing with negative numbers. Generally, the minimum pressure required, or the NPIPR, is sufficiently large that the normal sea level variations in atmospheric pressure can be neglected. At higher altitude it may be necessary to record the barometric pressure and increase the NPIP accordingly. Ninety percent of problems with RPDPs are associated with poor inlet conditions. Do not compromise when testing inlet pressure. The most effective way to measure inlet pressure is with a pressure transducer. Pressure variation generated by a smooth-running pump will mean that pressure gauges need to be glycerin-dampened to prevent them from being damaged. This dampening hides the fluctuation. At the frequency of the variations, an undamped gauge cannot respond fast enough. When there is a problem, the variations can be extremely violent. A pressure transducer requires circuitry to provide a stable input voltage and to display the output voltage. The choice of transducer and 53

AlChE Equipment Testing Procedure display must take into account the response rate needed to catch the transients. A value less than 20 kHz is unlikely to be useful. Inexpensive instruments that display mean and peak values of pressure are available. Output can always be ported to an oscilloscope to display the waveform. When instruments are calibrated, ensure that a square wave input signal produces an almost square wave output. It should not overshoot or undershoot. Know what the pressure is doing, not what the electronics are doing wrong! It is not always possible to fit transducers in ideal positions. However, aiming for the ideal will give more reliable results. Install the transducers with the "pocket" upwards. Fill with liquid when possible to reduce any possibility of dampening from air pockets. Do not fit to the outside or inside of bends. Fit the transducer as flush to the inside of the pipe as possible. If the pump is being run under conditions of severe cavitation, the transducer can be damaged when exposed for too long. If this is suspected then isolate the transducer with a valve to limit its exposure (at the expense of accuracy). Solve the problem of the cavitation before refitting the transducer correctly. 801.3 Discharge Pressure A glycerin-damped calibrated pressure gauge is often sufficient for measuring discharge pressure. (Note: the site gauge may not be reading cor redly!). However, if vibrations are a problem (pipe noise, fatigued welds, etc.) then the pressure transducer helps aid the analysis. The discharge pressure usually varies considerably because of varying restrictions to the flow. Absolute accuracy is not usually demanded, so use a transducer with a high maximum pressure to avoid damage from pressure spikes. 801.4 Differential Pressure RPDP produces flow of liquid, which is, ignoring compressibility effects, independent of the input pressure. The discharge pressure is solely determined by the downstream restrictions. High inlet pressure will, however, reduce the power absorbed. Inlet pressures in typical installations are usually not high enough to be taken into account when determining the power requirement. Ensure that the maximum inlet pressure specified by the manufacturer is not exceeded. 801.5 Crankcase Temperature Crankcase temperature is not usually a consideration unless conditions are excessive (over 140° F), in which case it is necessary to 54

Positive Displacement Pumps ensure that the oil is capable of performing at this temperature, and the supplier has to be consulted. 801.6 Liquid Temperature Most methods for determining temperature are adequate. Ambient usually covers most applications. However, where cavitation is suspected, it is necessary to check the inlet pressure trace at the maximum possible liquid temperature. Feeding the discharge to a back pressure regulator and returning the bypass to the supply tank will often be sufficient to raise the feed temperature to the necessary value. 801.7 Vapor Pressure Vapor pressure is the most critical liquid characteristic for RPDPs. A margin in excess of vapor pressure is required at the inlet at all times, and will depend upon pump design (valve spring stiffness, etc.). The pressure in the liquid will be lowered as it is accelerated through the valve opening. The required margin will also depend on the liquid's characteristics as it approaches its vapor pressure. An example is the liquid's specific heat, which affects the vaporization temperature and rate. 801.8 Viscosity Pump flow is virtually independent of liquid viscosity until the viscosity reaches a value where the cylinder does not become filled quickly enough. This is dependent upon the rpm. For viscous liquids, the pump should run slower and increased NPIP may be required. Absolute accuracy for determining the viscosity is not needed. When checking, ensure that the lowest running temperature is used to determine the value. Then consult the pump manufacturer as to the maximum recommended rpm and NPIP for that viscosity. Very low viscosity applications are not usually recommended for positive displacement pumps. 801.9 Flow Rate Flow rate is the most important parameter to measure. A calibrated flow meter can be used, although these meters are expensive for the pressure ranges of these pumps. Using a back pressure regulator, and having the flow meter on the bypass line, allows a low-pressure flow meter to be used for testing. Ensure that there are no other valves or paths flow can pass through when fitting such a regulator. Do not isolate the safety valve, which must have an open exit port from which to check that it is not passing liquid. If it is practical, diverting the back pressure regulator bypass flow into a container for a timed duration is the most accurate method. The flow can fill a container to a prede-

55

AlChE Equipment Testing Procedure termined volume or it can be weighed before and after, and the mass adjusted by the specific gravity to get the volume. When these methods are impractical, or a number of pumps are running in identical installations and need to be tested, a calibrated orifice is another solution. The pressure generated to force the flow through the orifice is recorded, and then checked against the orifice calibration to determine the flow rate. 801.10 Input Power For an electric drive it is possible to measure the input voltages and currents and use the formulae given in paragraph 400.3. If there is a gearbox or pulley drive causing a speed reduction, then this can absorb up to 5% of the input power. If there is a high power absorption by the speed reducer, then there will be evidence of abnormal heat generation. For sheave drives it is necessary to check for belt slip. Belt slip will cause heat buildup and premature belt failure.

802.0

Standardized Tests

802.1 Performance Test The purpose of this test is to check to see if the pump is performing according to specification. Usually it is only possible to test at the installed speed. However, when a variable speed drive is used, the tests can be repeated a number of times at different speeds and the results plotted. For multiple speed tests it is suggested that each set of results be separated by at least two empty lines when using Table 16. Before testing, obtain site information about causes for concern, such as loss of pressure, vibrations, etc. Set up the pump with the necessary instruments and piping gauges. In addition to installing the pressure transducer, the inlet piping should not be altered, as this will give a false test. If a back pressure regulator is installed, back off the adjustment. SLOWLY adjust the regulator until the desired pressure is reached. In the event that a complete turn of the adjustment does not give an increase in pressure, then back off one turn and adjust no further. Run the pump to purge the system of air for about 20 minutes. Then, take the required measurements as close to each other in time as is practical. Log the results. After testing, the manufacturer's data can be entered in a different color pen on the line under the test results in Table 16. The next line can be used to highlight differences that need attention. 56

Positive Displacement Pumps 802.2 Inlet Pressure Trace A pressure transducer should be fitted just upstream of any smoothing device. It should ideally be installed facing up with the pocket filled with liquid. This will avoid an air pocket that might dampen any signal. Connecting the transducer to a balanced Whetstone bridge circuit will give an output that can be viewed on an oscilloscope. A trace can be printed and compared with the maximum and minimum values provided by the manufacturer.

803.0 Other Tests 803.1 Sound Pressure Level A sound pressure level test can be carried out as per paragraph 500.3.1. 803.2 Analysis of Results Did the pump produce the correct flow against the back-pressure regulator? If "YES" — Inlet pressures acceptable? If "YES" — The pump is OK. Worn restrictions or other system problems may cause operational low pressure or vibrations. See paragraph 800.0 for more help. If " N O " — Improve the inlet conditions and re-test. See section paragraph 800.0 for explanation. If " N O " — Is the inlet pressure acceptable? If "YES" — Check the pump seals or packing rings, orings and all mating faces. Replace worn parts and re-test. If this has been done and the results still require a re-test, seek help from the manufacturer. If " N O " — Improve the inlet conditions and re-test.

804.0

Test Process Example

The instrumentation included a tachometer, a weighing scale, a pressure gauge, and a digital oscilloscope. All the instrumentation had been currently calibrated, and was accurate so that no correction needed to be made. Operators used the calibration table (Table 17), which records the instrumentation used. The inlet pressure trace is also shown in Table 18.

57

AlChE Equipment Testing Procedure

Figure 23. Horizontal triplex pump, Duty 12.5 US gpm, at 1275 psig for pumping methanol; tested using water.

Table 16. Test results

Maximum experimental error (48.55 - 48.40) MOO / 48.55 = 0.3% Accepted

58

Positive Displacement Pumps

Table 17. Calibration table

AlChE Equipment Testing Procedure Table 18. Inlet pressure trace

Positive Displacement Pumps 900.0 Auxiliaries 900.1

Appendix A: Seals

Sealing arrangements for positive displacement pumps are similar to other types of rotating equipment, such as centrifugal pumps. Positive displacement pumps may be sealed with packing or a mechanical seal, depending on the service conditions. The stuffing box or seal chamber is normally located on the suction side of the pump. The seal will then be subject to pump suction pressure. If the pump is run in reverse direction, the seal will be subject to discharge pressure. An example of a seal subject to reverse pressure can be found in applications involving high-suction lifts on progressing cavity pumps. Here reverse pressure operation, for a short period of time, occurs when the suction pipe is filled. If the suction line contains restrictions, such as a foot valve or similar device, the exit pressure from the pump to the seals can be excessive, which can result in damage to the sealing system. Some positive displacement pumps, such as screw pumps cannot, by design, run in the reverse direction. 900.1.1 Packing When packing is used to seal the equipment, care must be taken to ensure that the installation is done correctly. If the installation is the replacement of existing packing, be sure the sealing surfaces on a shaft or sleeve are not scored. Consult the manufacturer's recommended procedures for the installation of specific grades or types of packing. Note that the ends of the packing rings, when assembled to the equipment, must be off-set by 90° from each other for maximum leakage control. Basic causes for packing malfunction and tests for corrective action are: 900.1.1.1 Stuffing box overheats—Here the packing has been installed too tight. Release the gland pressure and retighten. Be sure leakage is present at the packing. 900.1.1.2 Pump leaks excessively—In this case, the packing may be too loose. Tighten the packing. If heavy leakage still continues, check for shaft or sleeve damage. Repair or replace as required. 900.1.1.3 Not enough liquid being delivered by the pump—In this case, suction pressure may be less than atmospheric pressure. Determine if air is leaking into the stuffing box when the pump is running. The corrective measure is to retighten the packing.

61

AlChE Equipment Testing Procedure 900.1.2 Mechanical Seals Many positive displacement pumps use mechanical seals. Once an installation is made, no further adjustments are required. However, liquid circulation to the seal chamber is required to remove the heat developed at the seal faces. Reliability of the entire pump and seal assembly is important and may be confirmed through dynamic and static testing. 900.1.2.1 Dynamic testing—Some applications will require a dynamic test before the unit is shipped from the pump manufacturer. Here water or oil would be used in a performance test and a visual check needs to be made of any leakage coming from the seal area. The acceptance criteria may vary depending on the application. Normally up to three drops of water per minute or a slight moistening of the exterior surface of the seal chamber with oil is acceptable after the pump has run briefly. 900.1.2.2 Static testing-Where practical and possible, the pump containing the seal can be pressurized with a test fluid, such as oil or air, and then blocked off. The pressure decay over a short period of time is then monitored. Air pressure tests are easier to perform. Air at 10 psig can be used for testing, and units are considered acceptable when the pressure decay is less than 2 psi over a period of 30 seconds. 900.1.2.3 Dual seal testing-Some applications involving fluids that are hazardous to the environment and present a safety issue to a chemical process plant or refinery may require a dual seal installation in either a double or tandem seal arrangement. Double seals may be tested statically in the pump using any pressure decay over a given period of time. Similarly, a tandem seal may be pressure tested statically as well. In this case, the pump and the inboard seal are pressurized to operating pressure. Leakage through the inboard seal of the tandem seal arrangement will be detected by a change of pressure in the outboard seal cavity. This is accomplished by blocking off the outboard seal cavity at atmospheric pressure for 10 minutes and noting the increase in pressure. Advances in seal technology and construction materials have allowed positive displacement pumps to be applied to more demanding applications such as hot chemicals and viscous fluids. As heat generated between the seal faces can become significant, manufacturers' recommendations for installation and cooling need to be implemented to avoid premature failure. 62

Positive Displacement Pumps 900.2

Appendix B: Bearings and Rotor Dynamics

The vibration of positive displacement pumps is typically not an issue in regard to expected performance. However, the design of the majority of these pumps can give rise to very large hydraulic forces. As a result of this fact, the pump components must be designed to avoid natural frequencies that could be excited by the system hydraulics. The rotor-bearing system should be designed so there is essentially rigid shaft performance over the expected operating speed range. This includes the excitation from the once per rev component but, more importantly, the multiple from the number of cylinders or chambers or vanes or gear teeth that produce the hydraulic force frequency to the casing vibration. No pump rotor or stator component should have a damped critical speed that is below 130% of the highest fundamental hydraulic force frequency. Calculations can account for hydraulic stiffness and damping of the pump element and the rotor sealing system. It is desirable to mount these pumps on rigid and or massive foundations that result in a casing rms. vibration level of less than 1 in/sec. Documented successful operation at higher vibration levels should also be available to users in order to justify these designs. The stiffness of the mounting structure to satisfy the above vibration levels can be predicted or verified by test data from the pump in place. A massive foundation, with a mass to hydraulic force ratio of 4 or more, is suggested to better assure that vibration levels are acceptable. Internal (product-lubricated) sleeve journal bearings are often used in many rotary pump designs. The lubrication of these product-lubricating bearings is critical to successful operation. If viscosity of the pumped fluid is sufficiently high, hydrodynamic lubrication occurs. In this case, the rotor does not contact the sleeve and so the composition of the bearing material is not important. However, if the viscosity of the pumped fluid is low, the fluid film supporting the rotor becomes thin or disappears, causing the rotor to contact the sleeve. The composition of the bearing material becomes very important in such cases. Typically, rotary pump product-lubricating bearings are made of bronze, iron, carbon, silicon carbide, or sometimes of plastics. A "dry running" (low-viscosity) lubrication of these bearings is characterized by the so called PV value, where P = bearing projected unit loading in psi, and V = journal velocity, ft/min. The approximate upper limits for these materials are listed below.

Table 19: Materials data for pump internals

63

AlChE Equipment Testing Procedure The selection of the material for the pump internals is also important. For example, gear pumps used for chemicals need to have a variety of material internals, such as stainless drive gear running against Teflon idler gear, or analogous dissimilar material combinations. Running similar material combinations, such as stainless steel against stainless steel, should not be used for gear pumps for chemicals, as galling can occur, and the life of a pump would be significantly reduced.

900.3

Appendix C: Piping

900.3.1 Piping-size considerations 900.3.1.1 Suction-a compromise between reducing the cost by using smaller pipe size, and providing sufficient suction pressure, in terms of NPSHA at the pump inlet by using larger pipe size. The smaller the pipe size, the higher the friction, and, consequently, the greater the NPHA losses. Historically, and as a rule of thumb, the suction pipe is normally set for flow velocities of 5 ft/sec or less. 900.3.2 Discharge piping Trying to minimize the installation cost by abruptly changing the size of the discharge pipe can create many problems. The turbulence created by an abrupt change in the discharge piping, known as the vena contracta effect, can significantly affect the performance of the pump. Because discharge piping typically is significantly longer then suction piping, and thereby has a more significant impact on cost, the rule of thumb and a primary approximation is to keep the velocity in the pump discharge pipe under 15 ft/sec. 900.3.3 Bringing an appropriately supported pipe to the pump. It should be realized that piping issues directly affect the pump's life and its performance. Bringing the pump to the pipe in one operation and expecting a good pump flange or vessel fit is a very difficult, if not impossible, task. When bringing the pipe to the pump, the last spool should always be left until the pump has been leveled in place and roughly aligned. At this point, the pipe should be securely anchored just before the last spool to prevent future movement toward the pump's flanges. Fig. 24 shows typical anchors at the pump suction.

64

Positive Displacement Pumps

Figure 24. Typical anchors for the pump piping Piping lay out should not be finalized until certified elevation drawings are received from the engineering group or from the pump vendor. Once the final certified prints are received, the final isometrics and the piping takeoff can be completed.

900.4 Appendix D: Installation Equipment can be delivered to a site either early or late. When the equipment is late, it is critical to have certified elevation prints of the equipment available when it arrives. The certified prints of the isometrics required for the piping takeoffs can be made without impacting the construction schedule. If the equipment is early, it will arrive at the site prior to the construction team's readiness. In such cases, early preparations must be made for long-term storage. It is customary to use oil mist lubrication to keep the equipment in as-shipped conditions during storage. Pressurization of the bearing housing and the casing with 10 to 20 psig H ^ O pressure prevents moisture and contaminants from entering the sealed areas and damaging the components. Early delivery of equipment to the site has the advantage of allowing for verification of actual measurements. Once the location of the equipment is set, the baseplate can be put in place, leveled and rough-aligned, and the equipment mounted. Rough alignment of the equipment should be done prior to building the grout forms, as illustrated in Figure 25. 65

AlChE Equipment Testing Procedure

Figure 25. Rough alignment phase.

Note that the motor and the pump are not coupled yet, and the baseplate is still sitting free, not grouted.

900.4.1 Grouting Once you are satisfied with the rough alignment, remove all the equipment (pump, motor gearbox, etc.) from the baseplate. Level the baseplate to a maximum out of level of 0.025" (0.06 mm) from end to end in two planes. Use machined pads as the base for the leveling instruments. Inspect the foundation for cleanliness, and, if not clean, use solvent to remove grease and oil. (See Figure 26).

66

Positive Displacement Pumps

Figure 26. Baseplate leveling pads and grout location Allow time for the cleaning substances to evaporate. Form the base using the appropriate techniques to allow for the weight, temperature rise, and fluidity of the grout material. Grout the base using epoxy grout. Allow the grout to cure, following the grout manufacturer's recommendations. This normally requires 24 hours at 80 °F (27 °C). Remove the forms and clean all sharp residue and edges from the foundation. Figure 27 shows details of a typical baseplate, with anchor bolts and grouting.

Figure 27. Typical anchor bolt and leveling wedges 67

AlChE Equipment Testing Procedure The rough alignment step mentioned earlier is critical to minimize the changes that will be required to appropriately fit the piping to the pump. At the last stage, when the final spools are installed, the final alignment will be achieved with small adjustments. This will minimize the adjustments required on the motor feet/bolts. Unfortunately, motor hold-down bolts are often too tight and allow only for small adjustments to the motor before becoming bolt bound. Motor manufacturers could improve this situation significantly if motor feet were designed to be slotted, rather than drilled, for bolts. Figure 28 shows the tightness of space available to insert the foot hold-down bolt.

Figure 28. Potential bolt-bound situation due to tight clearances between bolt, feet, and base This illustrates once again why good alignment at step 3 can save time and the cost of having to alter motor feet (a nightmare) by slotting or reaming. 900.4.2 Re-installation of the equipment and final alignment Reinstall the pump and the motor on the baseplate. Rough-align the equipment again, using reverse indicator or laser alignment or similar accurate techniques, as shown in Figure 29.

68

Positive Displacement Pumps

Figure 29. Rough alignment after grouting It should now be easy to fine-tune motor movement within the allowable alignment range without it becoming bolt bound. This is possible because of the rough alignment during the prior step (step 4). Note: Never install shims under the pump feet. If the shims are lost or mis placed, then alteration to the piping may be required to bring the pump to within the required alignment specification. The normal procedure is to place 0.125" (3.2 mm) thick shims under the motorfeet. This allows for the adjustments that will be required duringfinalalignment of the equipment.

Figure 30. Final connection of the suction piping

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AlChE Equipment Testing Procedure 900.4.3 Final piping installation Make up the final spool pieces for the suction and discharge spaces. Bring the piping to the pump as shown below.

Figure 31. Final piping 900.4.4 Final alignment Bring the piping to the equipment, take final measurements, and tack weld the spools in place. At this time the spools can be removed and taken back to the hot work permit area to finalize the weld. Leave a square and parallel gap between the flange faces. The gap should be wide enough to accommodate the size of the gasket required, plus 1/16 to 1/8", depending on piping sizing. (This is the only distance over which the piping will be pulled. However, because the piping is properly anchored before the spool pieces, this length is short, and stresses are minimized). Finally, align the equipment, taking into account hot and cold operating conditions, using two indicators on the pump shaft coupling area (Figure 32).

70

Positive Displacement Pumps

Figure 32. Overhead view of the motor and pump As the piping is tightened into place, the shaft must not be moved more than 0.002" (0.005 mm); modify the spool pieces until the piping misalignment is fixed. 900.4.5 Suggested periodic maintenance Several clues are common to piping misalignment. These clues become apparent when mechanical seals and/or bearings run hot, and parts fail. A quick analysis of the failed parts can clearly show evidence of piping misalignment. To make a final confirmation of the symptoms, unbolt the piping while measuring the movement in the vertical and horizontal plane. Again, piping that moves more than 0.002" (0.005 mm) must be modified to correct the misalignment. See Figure 33 for placement of the indicators.

71

AlChE Equipment Testing Procedure

Figure 33. Piping alignment verification Place an indicator in the horizontal and vertical planes, using the motor and pump coupling. Uncouple the pump and motor, while watching the indicator movement. Start unbolting the flanges, and continue watching for movement in the indicators. If the needle jumps over 0.002" (0.005 mm), the piping must be modified to improve the pump's performance.

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Positive Displacement Pumps 1000.0 References and Bibliography 1. Rotary Pump Standards, The Hydraulic Institute, Publication A N S I / H I 3.1-3.5, 3.6., 4.1-4.6, Parsippany, NJ, 2000. 2. API 610 Standard for Centrifugal Pumps, Revision 4 (ISO 13709), American Petroleum Institute, Washington, DC, October, 2004. 3. API 676 Standardfor Rotary Pumps, Revision 4, American Petroleum Institute, Washington, DC, March, 2000. 4. Centrifugal Pumps (Newtonian Liquids), 3rd Edition: A Guide to Performance Evaluation, Equipment Testing Procedure, AlChE, New York, June 2002. 5. Rotary Positive Displacement Pumps (Newtonian Liquids), 2nd edition, Equipment Testing Procedure, AlChE, New York, 1968. 6. Stepanoff, A.J., Centrifugal and Axial Flow Pumps, 2nd Edition, John Wiley & Sons, 1957. 7. Cameron Hydraulic Databook, 19th Edition, Flowserve Corporation, 5215 N. O'Connor Blvd., Suite 2300, Irving, T X 75039; www.flowserve.com. 8. Nelik, L., Centrifugal and Rotary Pumps: Fundamentals with Applications, CRC Press, Boca Raton, FL, 1999. 9. Rizo, L. and L. Nelik, "Piping-to-Pump Alignment," Pumps & Systems, April 1999.

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AlChE Equipment Testing Procedure INDEX Ambient Relative Humidity Anchor Bolts Baseplate Bearings Belt Slip Blow-by Test Bolts Break Horsepower Cavitation Compressibility

39 66

Glycerin Damping Grouting

53,54 64,66,68

3, 64-67 8, 23, 30, 35, 62,63,70 56 41,44 66,67 4, 5, 14-16,26

Head Positive Suction Pressure Pump Inlet Total Dynamic Velocity

3,4,36,41,46-47,51 3 36,41,47 3 4,36,41,47 4

3, 4, 30, 34, 54, 55 51,54

Inlet Port 4,52 Inlet Pressure. . 34,38,41,44,46,47,52,53-55,57

Damping 53,62 Diaphragm Pumps 11,37 Differential Pressure 3,4,6,13,18,19,24,54 Discharge 3, 4,8,10,12,21,53 Flange 3 Manifold 46 Port 14, 52 Pressure 6, 14, 19, 54 Valves 25 Dual Seal Testing 61 Dynamic Lift Capability . 36 Dynamic Viscosity 5,6 Elastomeric Material

Kinematic Viscosity

5,6,16,36

Lobe Pumps Lubrication

9,16 35,63,65

Materials of Construction Maximum Differential Pressure Discharge Pressure Operating Pressure Measurement Flow Temperature Vibration Pressure Mechanical Efficiency Minimum Required Suction Pressure Test Multiple-Screw Pumps

11,31-33

Flanges 3,13,24,63,71 Fluid Flow 32 Fluid Viscosity 13,17,24,32,33,46 Fluids 1,2,8,11,13,32-34,61 Flow, Net 3,5,13 Unit 13 Flow Measurement 13,32 Flow Meters 1,13,18,23,33,39,41,46,55 Flow Rate 18,33,34,36 41,46,53,55,56

8,11,62,63 24 24,52 27 13, 32 22.23,35 22,23,34 23, 32,52 56 29, 34 7,9,10,11,16,61

Net Flow 3-5,3 Net Positive Inlet Pressure 3,4,53,55 Net Positive Suction Head . . . 3,5,32,34,52,64 Newtonian Liquid 1,18 Non-Newtonian Liquid 1,17,18,32

Gauges . . . 1,13,17,24,36,37,38, 41,46,53,56 Gear Pumps 1,8,9,63

Packing Performance Curves

74

57,61 20

Positive Displacement Pumps

Performance Tests 22,23,33,34 Piping . . 1,3,21,32,36-38,51,52,56,64,65,69,72 Piston/Plunger Pumps 7,12,51 Power Fluid 4,5,15 Hydraulic 4,5 Pressure Air 36,37,41,42,44-47,62 Capability 31 Differential 3,4,6,13,18,19,24,54 Head 36,41,47 Fluid Discharge 37,38,54 Inlet 38,41,53-55,57 Minimum Required 29,30,53 Regulator 55,56 Sound 34,57 Suction 3,5,6,13,18,20-22,29,30,34,38,53, 61,64 Vapor 34,57 Pressure Spikes 52,54 Pressure Trace 52,60 Progressive Cavity Pumps . . . 7,10,11,15,31-35 Pump Types Diaphragm 11,37 Gear 1,8,9,63 Lobe 9,16 Multiple-Screw 7,9,10,11,16,61 Piston/Plunger 7,12,51 Progressive Cavity 7,10,11,15,31-35 Reciprocating Positive Displacement 7,12,51-60 Rotary 1,16-30,63 Vane 10,16

Rotor-Bearing System RPDP Piping Problems

63 51,52

Seals 23,57,61,62,71 Double 62 Mechanical 61,71 Pump 57 Shaft 23 Shaft Speed 1,16-18,24,31,32,52,53 Sling Psychrometer 39 Slip 3-5,13,15,32,33,51,56 Sound Pressure Levels 22,23,34,57 Start-up Pressure 41,42 Stall Pressure 42 Stator 11,31,33,34,63 Strobe Tachometer 13,17,24,33 Stuffing Box 61 Suction 3,5,11,12,16,21,24,30,36,61 Suction Manifold 46 Suction Piping 36,61,64,69 Suction Ports 5,16 Suction Pressure 3,5,6,17,18,20,21,29,30, . 34,38,53,61,64 Actual Available 3 Maximum Required 29 Minimum Required 22,29,34 Suction Valves 21,25,29 Synchronous Motor Speed 33 Test Procedures Tests Blow-by Dual Seal Dynamic Life Performance Static Suction Pressure Throttling Valves Torque Total Dynamic Head

Radial Hydraulic Force 8,10 Reciprocating Positive Displacement Pumps (RPDP) 7,12,51-60 Resisting Load 5 Reverse Pressure 61 Rotary Pumps 16-30,63 Rotor 9-11,31,33,63

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1,24,30 41,44 62 62 42,43 18,24,33,34,56 62 29,34 21 1,5,6,18,51 4,36,41,47

AlChE Equipment Testing Procedure Unit Flow

13

Vacuum Valves Suction Throttling Vane Pumps

Variable Frequency Drive 33 Viscosity 4-6,8,11,13,16-18,21, 24,26,30,32-33,38,46,52,55,63 Dynamic 5,6 Kinematic 5,6,16,36 Volumetric Efficiency 4,6,27,32,51

3,44,45 21,25,29,38,41,52,55 21,25,29 21 10,16

Other Equipment Testing Procedure Titles Centrifugal Pumps (Newtonian Liquids), Third Edition: A Guide to Performance Evaluation Continuous Direct-Heat Rotary Dryers: A Guide to Performance Evaluation, Third Edition Fired Heaters Mixing Equipment (Impeller Type), Third Edition Particle Size Classifiers, Second Edition Spray Dryers Tray Distillation Columns, Second Edition

For information on these and other titles, check AlChE's online catalog at

http://www.aiche.org/pubcat

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