Measurement and safety

Measurement

and Safety

INSTRUMENT AND AUTOMATION ENGINEERS’ HANDBOOK

FIFTH EDITION

VOLUME I

Measurement

and Safety

VOLUME I

INSTRUMENT AND AUTOMATION ENGINEERS’ HANDBOOK

FIFTH EDITION

BÉLA G. LIPTÁK, Editor-in-Chief

KRISZTA VENCZEL, Volume Editor

CRC Press

Taylor & Francis Group

6000 Broken Sound Parkway NW, Suite 300

Boca Raton, FL 33487-2742

© 2017 by Bela G. Liptak

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Version Date: 20160725

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Library of Congress Cataloging‑in‑Publication Data

Names: Liptâak, Bâela G., editor.

Title: Instrument and automation engineers’ handbook : measurement and safety

/ editor, Bela Liptak.

Other titles: Instrument engineers’ handbook.

Description: Fifth edition. | Boca Raton : Taylor & Francis, CRC Press, 2017.

| Revision of: Instrument engineers’ handbook. | Includes bibliographical

references and index.

Identifiers: LCCN 2016025938 | ISBN 9781498727648 (hard back : alk. paper)

Subjects: LCSH: Process control--Handbooks, manuals, etc. | Measuring

instruments--Handbooks, manuals, etc. | Automatic control--Handbooks,

manuals, etc. | Plant engineering--Safety measures--Handbooks, manuals,

etc.

Classification: LCC TS156.8 .I56 2017 | DDC 658.2/8--dc23

LC record available at https://lccn.loc.gov/2016025938

Visit the Taylor & Francis Web site at

http://www.taylorandfrancis.com

and the CRC Press Web site at

http://www.crcpress.com

This handbook is dedicated to the next generation of automation engineers working

in the fields of measurement, control, and safety. I hope that learning from these

pages will increase their professional standing around the world and that our

knowledge accumulated during the last half century will speed the coming of

the age of full automation. I also hope that what we have learned in optimizing

industrial processes will be used to improve the understanding of all processes and

that this knowledge will also help in overcoming our environmental ills and will

smooth the conversion of our lifestyle into a sustainable, safe, and clean one.

Béla G. Lipták

vii

C o n t e n t s

Introduction xi

Contributors xxiii

1 General Considerations 1

1.1 Accuracy and Rangeability 4

1.2 Binary Logic Diagrams 15

1.3 Calibration 27

1.4 Configuring Intelligent Field Devices 35

1.5 Evaluation of Instrument Quality 56

1.6 Instrument Installation 65

1.7 Redundant and Voting Systems 84

1.8 Soft Sensors 107

1.9 Terminology for Automation and Testing 119

1.10 Uncertainty: Estimation, Propagation, and Reporting 151

2 Flow Measurement 159

2.1 Flowmeter Selection 167

2.2 Applications: Abrasive, Corrosive, Slurry 205

2.3 Applications: Bidirectional Flowmeters 211

2.4 Applications: Multiphase and Subsea Flowmeters 221

2.5 Applications: Multiphase Hydrocarbon Metering 235

2.6 Calibration and Maintenance 246

2.7 Installation 261

2.8 Anemometers 270

2.9 BTU Flow Measurement: Fuel Gas 279

2.10 BTU Flow Measurement: Liquids 284

2.11 Cross-Correlation Flowmetering 290

2.12 Elbow Flowmeters 299

2.13 Flow Switches 306

2.14 Laminar Flowmeters 317

2.15 Magnetic Flowmeters 326

2.16 Mass Flowmeters: Coriolis 346

2.17 Mass Flowmeters: Indirect and Turbine 364

2.18 Mass Flowmeters: Thermal 371

2.19 Metering Pumps 384

viii Contents

2.20 Oil-Custody Transfer 394

2.21 Orifices 412

2.22 Paddle Flow Switches 437

2.23 Pitot and Area-Averaging Tubes 445

2.24 Positive-Displacement Gas Meters 460

2.25 Positive-Displacement Liquid Meters and Provers 469

2.26 Purge Flow Regulators 482

2.27 Segmental Wedge Flowmeter 486

2.28 Sight Flow Indicators 492

2.29 Solids Flowmeter and Feeder 500

2.30 Target Meters 525

2.31 Turbine and Other Rotary Element Flowmeters 531

2.32 Ultrasonic Flowmeters 550

2.33 Variable Area, Gap, and Vane Flowmeters 567

2.34 Venturi, Proprietary Tubes, and Flow Nozzles 578

2.35 Vortex and Fluidic Flowmeters 593

2.36 V-Shaped Cone Flow Elements 606

2.37 Weirs and Flumes for Open Channels 612

3 Level Measurement 621

3.1 Selection of Level Detectors 627

3.2 Installation Considerations 648

3.3 Applications: Interface, Foam, Boiling Services 653

3.4 Applications: Non-Contacting, Non-Penetrating 660

3.5 Applications: Tank Gauges for Oil and Gas 665

3.6 Applications: Water Level Measurement in Nuclear Reactors 680

3.7 Bubblers 686

3.8 Capacitance and Radio Frequency (RF) Admittance 697

3.9 Conductivity and Field-Effect Level Switches 715

3.10 Diaphragm Level Detectors 720

3.11 Differential Pressure Level Detectors 727

3.12 Displacer Type Level Detectors 748

3.13 Float Level Devices 762

3.14 Laser Level Sensors 773

3.15 Level Gauges, Including Magnetic 782

3.16 Magnetostrictive Level Transmitters 798

3.17 Microwave Level Switches 804

3.18 Optical and IR Level Switches 811

3.19 Radar: Contact Level Sensors (TDR, GWR, and PDS) 816

3.20 Radar: Non-Contacting Level Sensors 825

3.21 Radiation Level Sensors 835

3.22 Resistance Tapes 855

3.23 Rotary Paddle Switches (Solids Level Detector) 863

3.24 Tank Farm Gauges for Liquids and Solids 868

3.25 Thermal Dispersion Level Sensors 880

3.26 Ultrasonic Level Detectors 884

3.27 Vibrating Level Switches 897

4 temperature Measurement 901

4.1 Selection of Temperature Sensors 905

4.2 Applications: Cryogenic Temperature Measurement 936

4.3 Applications: High Temperature 942

4.4 Bimetallic Thermometers 965

4.5 Calibrators and Simulators 971

Contents    ix

4.6 Cones, Crayons, Labels, Paints, and Pellets 977

4.7 Filled-Bulb and Glass-Stem Thermometers 983

4.8 Integrated Circuitry (IC), Transistors and Diodes 997

4.9 Miscellaneous Temperature Sensors 1003

4.10 Optical Fiber Thermometers (OFT) 1012

4.11 Radiation Pyrometers: Infrared (IR), Total, and Optical 1022

4.12 Resistance Temperature Detectors (RTDs) 1040

4.13 Temperature Switches and Thermostats 1055

4.14 Thermistors 1067

4.15 Thermocouples 1078

4.16 Thermowells 1108

4.17 Ultrasonic Thermometers 1125

5 Pressure Measurement 1131

5.1 Selection of Pressure Detectors 1134

5.2 Accessories (Seals, Snubbers, Calibrators, Manifolds) 1145

5.3 Bellows Elements and Barometers 1159

5.4 Bourdon and Helical Pressure Sensors 1166

5.5 Diaphragm or Capsule Elements 1171

5.6 Differential Pressure Instruments 1178

5.7 Electronic Pressure Sensors 1192

5.8 High-Pressure Sensors 1208

5.9 Manometers 1214

5.10 Pneumatic Repeaters and Boosters 1226

5.11 Pressure and Differential Pressure (D/P) Switches 1232

5.12 Pressure Gauges 1242

5.13 Pressure Scanners 1252

5.14 Vacuum Sensors 1259

6 Density Measurement 1275

6.1 Selection of Density Detectors 1278

6.2 Displacement and Float-Type Densitometers 1293

6.3 Gas Densitometers 1301

6.4 Hydrometers 1313

6.5 Hydrostatic Densitometers 1317

6.6 Oscillating Densitometers (Coriolis) 1326

6.7 Radiation Densitometers 1333

6.8 Ultrasonic Sludge Slurry Densitometers 1343

6.9 Vibrating Densitometers 1347

6.10 Weighing Densitometers 1356

7 Miscellaneous sensors 1361

7.1 Building Optimization Sensors 1367

7.2 Electric Energy Management: Demand Shedding 1383

7.3 Electric Meters 1389

7.4 Machine Vision Technology 1406

7.5 Metal Detectors 1413

7.6 Noise Sensors and Nondestructive Testing 1419

7.7 Nuclear Reactor Measurements 1429

7.8 Pipe Integrity Gauges (PIGs) 1443

7.9 Position Measurement, Linear and Angular 1458

7.10 Proximity Sensors and Limit Switches 1471

7.11 Solar Collector Positioning 1484

x Contents

7.12 Tachometers and Angular Speed Detectors 1490

7.13 Thickness and Dimension Measurement 1499

7.14 Torque and Force Measurement 1508

7.15 Transportation Related Sensors 1520

7.16 Vibration, Shock, and Acceleration 1537

7.17 Visual Inspection Tools, Borescopes 1556

7.18 Weather Stations 1562

7.19 Weight Detectors Load Cells 1574

7.20 Weighing Systems 1606

8 safety sensors 1627

8.1 Annunciators and Alarms Management 1632

8.2 Electrical and Intrinsic Safety 1660

8.3 Excess Flow and Regular Check Valves 1677

8.4 Explosion Proofing of Instrumentation 1685

8.5 Explosion Suppression and Deluge Systems 1712

8.6 Flame Arrestor, Conservation and Emergency Vents 1722

8.7 Flame, Fire, and Smoke Detectors 1733

8.8 Nuclear Accidents 1743

8.9 Nuclear Radiation Detectors 1765

8.10 Oil Industry Accidents 1779

8.11 Relief Valves: Determination of Required Capacity 1802

8.12 Relief Valves: Sizing, Specification, and Installation 1825

8.13 Rupture Discs 1858

9 transmitters 1873

9.1 Transmitters: Electronic 1875

9.2 Transmitters: Fiber-Optic 1894

9.3 Transmitters: Pneumatic 1907

9.4 Transmitters: Smart, Multivariable 1922

9.5 Transmitters: Wireless 1933

Appendix 1941

A.1 Definitions 1943

A.2 Abbreviations, Acronyms, and Symbols 1990

A.3 Organizations 2010

A.4 Flowsheet and Functional Diagrams Symbols 2013

A.5 Conversion among Engineering Units 2060

A.6 Chemical Resistance of Materials 2097

A.7 Composition and Properties of Metallic and Other Materials 2120

A.8 Steam and Water Tables 2127

A.9 Friction Loss in Pipes 2135

A.10 Tank Volumes 2141

Index 2145

xi

I n t r o D u C t I o n

ArtIFICIAL InteLLIGenCe

I am breaking the traditions of scientific books by writing in

these paragraphs about issues that go beyond science. The

tradition of engineering handbooks is to present material that

we are fairly sure of and here, when I write about artificial

and super intelligence, I am on uncharted territory.

Automation opened a new chapter in human evolution,

because while it started as just another tool to make our lives

easier, with the development of robots, instant communica￾tion, and artificial intelligence, it is becoming much more.

This can be a great achievement, but it can also be the slip￾pery slope on our road of progress, one that we should not

take, because we could be risking human civilization.

It seems to me that throughout the ages, man was not only

struggling for survival, but was also struggling to understand

the universe and its purpose. Our ancestors traveled on two

roads. One was spiritual, and the other was scientific. Those

on the spiritual road assumed that understanding the intent of

the creator is beyond the abilities of humans, while the ones

on the road of science decided to try to understand it anyway!

Scientists focused on learning the laws that are guiding the

universe and thereby learning something about its creator.

The ones traveling on this second road included Aristotle,

Copernicus, Galileo, Newton, Einstein and now people like

Hawking. It matters little if Galileo discovered gravity,

because an apple fell on his head or because he climbed the

leaning tower of Pizza and noticed that bodies of different

weights increased their velocity at the same rate. It matters

little how the discovery of relativity, black holes, or the con￾tinuous expansion of the universe was achieved. What mat￾ters is our proving that we are capable of understanding the

laws that give order to and govern the universe and we still

keep learning more and more about them.

If we see a painting, we do not need any further proof

to know that there was a painter who created it. When we

observe the universe, we know that it too had a creator. But

just as we have to study the painting more, until it reveals

something about the painter, we have to study the universe,

to even begin to understand its creator. Over the millennia,

we have gained a bit of this understanding, but over this same

period, some have also developed the view that the spiritual

and scientific roads lead to different intellectual destinations,

that they do not merge, but contradict each other.

Well, it seems we were wrong! Today’s science has

proven, that time was created at the same time when space

and matter was, that neither time, nor space existed before

that. Scientists call this event the “big bang” and just as

Newton’s apple and Einstein’s relativity represented a quan￾tum jump in our understanding of the universe, the “big

bang” adds to it. This addition is important, because it proves

that the spiritual and scientific roads can merge.

Automation, robots, and AI

So does all this have anything to do with automation? Well,

automation opened a new age for mankind. First, it was just a

tool that served our comfort as it substituted for our muscles

and later for the routine functions of our brain. But today

we are beginning to realize that we have “created” some￾thing much more (Figure I.1). When we designed the first

gadgets that made industry safer and more efficient, we did

not realize where this will lead. Next we designed “smart”

instruments just so that we will not need to keep checking if

they are okay, because they could do it themselves through

“self-diagnosis.” This road naturally led to robots and today,

we are beginning to realize that these “human creations” are

much more than “mechanical slaves”!

Fig. i.1

Our creation the robot, which might get smarter than its creator.

(Courtesy of Can Stock Photo.)

xii Introduction

Robots can not only do things that we hate to do, because

they are boring, they can not only do them better and faster,

but they can also go to places which are unhospitable for us,

such as Mars or the war zones. And now, we are beginning to

realize that they can also change our life style! Today, when

our robots can not only build our cars, but can also drive

them, we begin to ask, does our “creation” make “the cre￾ator” unnecessary. And by this, I do not mean only that they

create unemployment!

When we in the automation profession created these

machines of unlimited memory and speed to analyze data

and execute logic, we have created a machine that could

have “superhuman intelligence.” It seems to me that artifi￾cial intelligence (AI) can not only build and drive cars, but

eventually can design them and can make them better. In the

same token, they can also design better robots. And when we

get to that point, when they can improve their own software,

they can become more intelligent than humans.

Naturally, we have just started on this slippery slope! We

are just beginning to sink to become “keyboard clickers” and

intellectual garbage consumers! But what is worst, we have

no idea where this road leads us or the next generations? Yet

we know that robots can not only spread fertilizer, but they

can also spread say, the Abola virus and to their present “AI

brain,” it is the same.

You might say that this is farfetched. You might believe

that AI will only be used for tasks like analyzing our genetic

code to unlock the secret of eternal youth. Well, this could

turn out to be only wishful thinking. Remember that we were

created with a conscience and machines have no “inner man”

unless we give them one. Therefore, the AI of robots is not

necessarily beneficial (Figure I.2).

the Dilemma

We do not know if it would be necessary and/or possible to

bestow morals to robots before we “let them loose.” Yet some

(like Stephen Hawking or Bill Gates) believe that superhuman

AI, that does not share human values, could be dangerous.

I certainly do not know the answer to these questions.

Obviously, I know that robots could replace us in today’s

workforce, but that in itself is not necessarily bad, because

technological unemployment could just free us to have more

time for our passions. Unfortunately, I am also beginning to

believe that AI could cause humans to become detached from

culture itself. Obviously, AI in the wrong hands can also do

immense harm, but danger as such is not new. After all man￾kind faced and survived many evils in the past, including the

mental poisons of brain washing by fanatics or the physical

dangers posed by nuclear weapons.

One could argue that AI does not have to be either benev￾olent nor evil, that it is possible to design it so, that it will be

simply neutral. But is that good enough? Can we live with a

machine that has a superior intelligence and no conscience?

In any case, we must realize that AI is more than a tool and

that it is up to us to overcome the potential risks it can pose,

before we “let it loose.” It is up to us, the automation engi￾neers, to give our “child” the upbringing it deserves, so that

when it reaches the age of super intelligence, it will not be

uncontrolled, but sage and sapient.

I started to work on the first edition of this handbook

when I was 25 years old. Today, when you start turning the

pages of this fifth edition, I am 80. This book started out as

an American handbook on instrumentation while today it is

an automation reference source used on all five continents.

When I started writing it, the toilet float and the thermostat

were considered to be automation and John von Neumann´s

Institute for Advanced Study (IAS) computer was barely

operational (Figure I.3). It was a time when vacuum tubes

had just been replaced by silicon transistors and nobody had

yet heard of metal–oxide–semiconductors (MOS) semicon￾ductors or microprocessors.

Fig. i.3

John von Neumann’s IAS computer.

Fig. i.2

Can this brain do more than just regurgitate what we put in it?

(Courtesy of John Keller.)

Introduction    xiii

And where are we today? We operate robots on Mars that

can vaporize the rocks using laser to determine their compo￾sition, and soon, we will be ordering pizza while sitting in

our hydrogen-fueled driverless cars so that the drone-deliv￾ered pizza will be hot and waiting for us in the driveway by

the time our smart car has completed parking itself.

Our profession has changed a lot during the last five

decades. In the first edition of my handbook, I was describing

how to tune single loop pneumatic controllers and was perfectly

satisfied with using filled bulbs for temperature and orifices for

flow measurement. At that time, the main job of the instrument

department in the plant was to clean plugged pressure taps and

stuck control valves, that our control panels were full of push

buttons, blinking lights, and manual loading stations.

At the time of the first edition, I was teaching process

control in the chemical engineering department of Yale

University, and my handbook was published in the electrical

engineering division of my publisher. Why? Not because

Yale or Chilton had something against our profession! No,

it was because they did not even know that the automation

profession existed!

Things have changed! Today, it is the basic know-how of

chemical or electrical engineering that is taken for granted,

and the focus is on the almost daily advances in automation

and optimization. The increased importance of automation

is helped by the dropping cost and increased reliability of

computers, the increased availability of self-checking digi￾tal components, wireless transmission, redundant backup,

ease of configuring complex algorithms, and generating

dynamic displays. Today, it is finally being realized that it is

only our profession that can simultaneously maximize the

production and safety of just about any industrial process; it

is automation that can be minimizing operating and energy

costs while maximizing both safety and profitability.

tHIs HAnDBooK

the Birth of this Handbook

In 1956, we Hungarians rose up to get rid of both Communism

and Soviet occupation. Our revolution was crushed and

250,000 young and educated Hungarians (2.5% of the popu￾lation) escaped. I was one of them. I received a scholarship

at the Stevens Institute of Technology and graduated there as

a naval architect in 1958, but I could not get a job, because

all ship design firms had some connection with the Navy and

I was considered to be a “security risk,” because my family

lived behind the Iron Curtain. So I had to pick a new profes￾sion and luckily I picked automation.

At this point I got lucky, because an engineer named Sam

Russell was just starting an engineering firm and he hired me.

Sam worked for President Roosevelt during WW2 in the effort

to replace the natural rubber supplies blocked by the Japanese

with synthetic rubber. Sam knew how to get things done! His

engineering design firm, focusing on plastics, was a success,

and I, as his chief instrument engineer, had to hire more people.

At the age of 25 with my thick Hungarian accent, I did not

feel comfortable to hire experienced engineers twice my age, so

I asked Sam to let me hire smart, fresh graduates from schools

like MIT and Caltech and let me use one day a week to teach

them our profession. He agreed, and in a couple of years, we

had one of the best automation engineering departments.

I kept the notes I used in my weekly classes, a pile which

grew to over a foot high, as it accumulated at the corner of

my desk. At this point, I got lucky again, because an old

fashioned publisher named Nick Gronevelt visited me. He

reminded me of my grandfather, as his hair was parted in the

middle and the gold chain of his watch was hanging out of his

vest pocket. Nick asked about the pile of notes on my desk,

and when I explained, he decided to publish it.

It took me nearly 5 years to complete the three volumes

of the first edition. My goal was to produce an experience￾based practical and reliable book, written by users for users.

The coauthors included the representatives of suppliers

(Hans Baumann and Greg Shinskey) and of academia (Paul

Murrill and Cecil Smith), but my focus was on authors who

were speaking from personal experience and these people

were busy and not used to writing. Edward Teller wrote the

preface, and the 100+ authors of the first edition were all

respected professionals within their fields.

recent Changes

This fifth edition is the first, which is written for a global

audience. To convert the IAEH from an American to a uni￾versal handbook, overseas products are also included and

the coauthors also represent all five continents. The IAEH is

available not only in the printed form but also on DVD, flash

drive, or can be downloaded directly from the Internet.

To take further advantage of the digital age, the supplier

and reading material web addresses are provided so that

the reader can gain access to the specifications of a spe￾cific product of a particular manufacturer by a single click.

Similarly included are the web addresses of reading materi￾als, so if the reader wants to read more about a particular

subject, that too can be done by just another click. Finally,

we have paid special attention to providing a very thorough

index that should provide the reader with quick access to

specific information.

the Content

This first volume of the IAEH describes the sensors and

detectors used in the measurement of process variables, while

the second volume describes the analytical instruments that

are used online and/or in the laboratory for the determination

of the compositions of process fluids and gases. The chapters

of this volume are grouped into 10 sections:

Section 1: General Considerations

Section 2: Flow Measurement

Section 3: Level Measurement

xiv Introduction

Section 4: Temperature Measurement

Section 5: Pressure Measurement

Section 6: Density Measurement

Section 7: Miscellaneous Sensors

Section 8: Safety Sensors

Section 9: Transmitters

Section 10: Appendix

When the reader needs to decide which measurement device to

use for a particular application, it is recommended to start with

reading the first chapter in the corresponding section. That chap￾ter gives an overview of the capabilities of the various designs

within that category of sensors and also guidance concerning

the selection of the right ones for the various applications. If

the reader is too busy to read the whole chapter, he/she can just

review the Orientation Table in the front of that chapter:

orientation tables

In the selection process, the first step is to review the Orientation

Tables provided in the first chapter of each section. The

Orientation Table is a bird’s eye view of the capabilities of all the

sensors covered in that section, and thereby, it can quickly guide

the reader to the best sensor(s) for the application at hand. In

these tables, I have placed check marks in the rows and columns,

indicating the sensor categories that can be considered for a par￾ticular measurement application. After studying the table, the

reader should select two or three best candidates after reviewing

their ranges, accuracies, costs, etc., and select the one(s) that are

closest to the requirements of the application. If the information

provided in the Orientation Tables is insufficient and more detail

is needed on sensors’ capabilities, the reader should proceed to

the front page of the corresponding chapter, which provides a

Feature Summary of the particular measurement device.

Feature summaries

At the front of each chapter, a summary is provided of the

basic features of the instruments described in that chapter.

This summary allows the reader to quickly determine if for

the particular application that sensor category is worth further

consideration. The data provided in this summary include

Range

Accuracy

Rangeability (turndown)

Design pressure and temperature

Materials of construction

Cost

Suppliers

A brief statement of advantages and disadvantages

A partial list of suppliers is given in alphabetic order, and in

some cases, where such information is available, the “most

popular” ones are noted. Next to the name of each manu￾facturer is the web address, where the reader can find the

specifications of the manufacturer’s products.

Experienced automation engineers might make the selec￾tion after just checking the Orientation Table. Those who want

to refresh their memories concerning the many sensor options

and receive selection guidance and relative merits for the many

different applications might read the first chapter in the par￾ticular section. After that, the reader might turn to the Feature

Summary on the front page of the specific chapter to find accu￾racy, rangeability, cost, supplier, and other information. If time is

available, it is also advisable to completely read the whole chap￾ter describing that category of measurement devices, including

recent developments in their features and capabilities. Finally, if

one wants to study the differences in the design features of the

products of the different manufacturers listed at the end of the

Feature Summary, they can visit the web addresses given there,

where the detailed specifications are provided.

Handling a Project

Once the selection of the sensor type is concluded, it is time to

use the specifications to obtain bids. In this handbook, at the end

of each chapter, there is a specification form for that purpose.

The form in most cases was prepared by International Society of

Automation (ISA), but any other forms can also be used as long

as they fully describe the process conditions and requirements

of the application. Once the specification form is completed, it is

time to obtain quotations from a half dozen suppliers.

Over the years, I have found that obtaining early bids from

the vendors is valuable, because the quotations usually bring up

additional considerations that help in making the right selection

in two ways. One valuable contribution to finding the best solu￾tion is that while several suppliers prepare their quotations, they

will ask a number of questions, which could have been over￾looked earlier, and by answering those questions, designers and

their clients will better understand their own requirements.

The other valuable advantage that early bidding provides is

accurate cost estimates, because until quotations are received,

estimates tend to be inaccurate. Once the bids are in, and the

bid analysis is prepared, costs, accuracies, rangeabilities, cali￾bration, and maintenance requirements are known and guar￾anteed. For these reasons, it is my recommendation that the

bid specifications be prepared at the early stage in the project.

This does not mean that the supplier will be selected as soon

as quotations are received. No! One’s options should be kept

open at this stage, but it does mean that from this point on the

decision will be based on guaranteed facts.

the Appendix

The Appendix contains information that engineers have to

look up daily and is provided here to save the time of search￾ing. The following data and information are provided in the

chapters of the Appendix section in the back of this volume:

Chapter A.1 Definitions

Chapter A.2 Abbreviations, Acronyms, and Symbols

Chapter A.3 Organizations

Chapter A.4 Flowsheet and Functional Diagrams Symbols