Glossary of Terms Used in the Measurement of Fluid Flow in Pipes

AN A MERICAN NA TIONAL S T AND ARD

ASME MFC-1–2014

[Revision of ASME MFC-1M–2003 (R2008)]

ASME MFC-1–2014

[Revision of ASME MFC-1M–2003 (R2008)]

Glossary of Terms Used in the Measurement of Fluid Flow in Pipes

AN AMERICAN NA TIONAL S T AND ARD

Two Park Avenue • New York, NY • 10016 USA

Date of Issuance: August 28, 2015

This Standard will be revised when the Society approves the issuance of a new edition.

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CONTENTS

iii

FOREWORD

The greatest aid to communication, whether verbal or written, is a common vocabulary. Even within a single technical discipline, the same word can have different meanings to different people. In order to help overcome this obstacle in the field of fluid flow measurement, this Standard consists of a collection of terms and their definitions so that a common base of reference is available, so we can speak a common language.

To this end, we need to understand that language is fluid and the definitions given here provide a snapshot of usage at the time of publication. In the preparation of this Standard, an attempt has been made to standardize suitable terms and not to perpetuate unsuitable ones, merely because they have been used in the past. Recognition of terms in common parlance is acknowledged and less ambiguous ones are suggested. Self evident and irrelevant terms have been excluded, as have those terms that are unique to methods of measurement not widely used.

The international standard vocabulary and symbols concerning the measurement of fluid flow in closed conduits prepared by ISO/TC30 has been considered, as well as many other reference sources, both national and international, have been used in order to make this glossary as useful as possible to a broad segment of the measurement community. This Standard varies from earlier revisions in that all terms are listed alphabetically.

The first edition of this Standard was approved by the American National Standards Institute on October 15, 1979. It was subsequently reaffirmed, without change, on August 7, 1986. The previous edition of this Standard was approved by the American National Standards Institute (ANSI) on September 10, 2003. It was subsequently reaffirmed, without change, in 2008.

Suggestions for improvement of this Standard are welcome. They should be sent to Secretary, ASME MFC Standards Committee, Two Park Avenue, New York, NY 10016-5990.

This revision was approved by the American National Standards Institute on August 1, 2014.

iv

ASME MFC COMMITTEE

Measurement of Fluid Flow in Closed Conduits

(The following is the roster of the Committee at the time of approval of this Standard.)

STANDARDS COMMITTEE OFFICERS

R. J. DeBoom, Chair

Z. D. Husain, Vice Chair

D. C. Wyatt, Vice Chair

C. J. Gomez, Secretary

C. J. Blechinger, Honorary Member, Consultant

R. M. Bough, Rolls-Royce Corp.

M. S. Carter, Flow Systems, Inc.

G. P. Corpron, Honorary Member, Consultant

R. J. DeBoom, Consultant

STANDARDS COMMITTEE PERSONNEL

G. E. Mattingly, The Catholic University of America

R. W. Miller, Honorary Member, R. W. Miller and Associates, Inc.

A. Quraishi, American Gas Association

W. Seidl, Colorado Engineering Experiment Station, Inc.

D. W. Spitzer, Contributing Member, Spitzer and Boyes LLC

D. Faber, Contributing Member, Badger Meter, Inc.

C. J. Gomez, The American Society of Mechanical Engineers

F. D. Goodson, Emerson Process Management/Daniel Division

Z. D. Husain, Chevron Corp.

C. G. Langford, Honorary Member, Consultant

T. O. Maginnis, Consultant

W. M. Mattar, Invensys/Foxboro Co.

R. N. Steven, Colorado Engineering Experiment Station, Inc.

T. M. Kegel, Alternate, Colorado Engineering Experiment Station, Inc.

J. H. Vignos, Honorary Member, Consultant

D. E. Wiklund, Emerson Process Management/Rosemount Division

J. D. Wright, Contributing Member, NIST

D. C. Wyatt, Wyatt Engineering

D. C. Wyatt, Chair, Wyatt Engineering

R. J. DeBoom, Consultant

SUBCOMMITTEE 1 — GLOSSARY OF TERMS

G. E. Mattingly, The Catholic University of America

A. Quraishi, American Gas Association

F. D. Goodson, Emerson Process Management/Daniel Division

Z. D. Husain, Chevron Corp.

R. N. Steven, Colorado Engineering Experiment Station, Inc.

D. E. Wiklund, Emerson Process Management/Rosemount Division

v

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vi

ASME MFC-1–2014

GLOSSARY OF TERMS USED IN THE MEASUREMENT OF FLUID FLOW IN PIPES

1. GENERAL

   1. Scope

      This Standard consists of a collection of definitions of those terms that pertain to the measurement of fluid flow in pipes. The definitions provided also give guid- ance for recommended usage in the application of flow measurement devices.

   2. Organization

      This Standard is organized alphabeticlly. Symbols nor- mally applied to various quantities are tabulated in section 3.

   3. References

      This Standard was compiled from many sources, including various reports and standards from The American Society of Mechanical Engineers (ASME), the American Gas Association (AGA), the American Petroleum Institute (API), the International Society of Automation (ISA), the British Standards Institute (BSI), the International Organization for Standardization (ISO), the National Institute for Standards and Technology (NIST), and the International Organization of Legal Metrology (OIML).

      
      

2. GLOSSARY OF TERMS

absolute pressure: algebraic sum of the atmospheric pres- sure and gauge pressure.

absolute static pressure of a fluid: static pressure of a fluid measured with reference to a perfect vacuum.

acceptance test: the evaluating action(s) to determine if an instrument satisfactorily meets its performance criteria, permitting the owner/purchaser to formally accept it from the supplier.

accuracy of measurement: the extent to which a given mea- surement agrees with a reference for that measurement; often used by manufacturers to express the performance characteristics of a device.

NOTE: “Accuracy” is not the same as “uncertainty” (see “uncer- tainty of measurement”).

acoustic matching layer: material comprising one or more

acoustic path: the path that the acoustic signals follow as they propagate through the measurement section between the transducer elements.

acoustic ratio: the differential pressure ratio divided by the isentropic exponent (compressible fluid).

air: mixture of gases and associated water vapor sur- rounding the earth; dry air plus its associated water vapor. The term is used synonymously with atmosphere.

air, dry: mixture of dry gases present in the atmosphere.

ambient temperature: temperature of the atmosphere mea- sured in the immediate vicinity of the point of measure- ment and unaffected by wind or other atmospheric phenomena.

annular chamber: piezometer ring integral with the pipe or the primary device that simplifies the construction of annular pressure taps.

annular space: area between the tapered tube and the float that normally increases as the float rises.

area meters: flowmeter in which a variation in the cross section of the fluid stream under constant head is used as an indication of the rate of flow, e.g., a float is sus- pended in a vertical tapered tube and as the fluid flow rate changes, the position of the float in the tube changes.

arithmetic mean: the sum of values divided by the number of values, also called “average.”

NOTES:

1. The term “mean” is used generally when referring to a popula- tion parameter, and the term, “average,” when referring to the result of a calculation on the data obtained in a sample.

2. The average of a simple random sample taken from a popula- tion is an unbiased estimator of the mean of this population. Other estimators, such as the geometric or harmonic mean, the median, or the mode are sometimes used.

atmospheric pressure: force per unit area exerted by the atmosphere.

NOTE: Standard atmospheric pressure is 760 mm of mercury at 0°C. This is equivalent to 101.325 kPa and 14.696 psia.

average value: arithmetic mean of n readings of the quantity x. The average value x is calculated using the following formula

layers, selected to maximize the acoustic coupling coeffi- 1 n

cient between two media.

n

Xw p xi

ip1

1