Isa 5.1

AMERICAN NATIONAL STANDARD

ANSI/ISA–S5.1–1984 (R1992)

Instrumentation Symbols
and Identification

Reaffirmed 13 July 1992

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ANSI/ISA-S5.1 — Instrumentation Symbols and Identification

ISBN 0-87664-844-8
Copyright © 1984 by the Instrument Society of America. All rights reserved. Printed in the United
States of America. 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, or
otherwise), without the prior written permission of the publisher.
ISA
67 Alexander Drive
P.O. Box 12277
Research Triangle Park, North Carolina 27709

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COPYRIGHT 2003; The Instrumentation, Systems, and Automation Society

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Preface

This preface is included for information and is not a part of ANSI/ISA-S5.1.
This standard has been prepared as part of the service of ISA toward a goal of uniformity in the
field of instrumentation. To be of real value, this document should not be static, but should be
subject toperiodic review. Toward this end, the Society welcomes all comments and criticisms,
and asks that they be addressed to the Secretary, Standards and Practices Board, ISA, 67
Alexander Drive, P.O. Box 12277, Research Triangle Park, NC 27709, Telephone (919) 5498411, e-mail: standards@isa.org.
The ISA Standards and Practices Department is aware of the growing need for attention to the
metric system ofunits in general, and the International System of Units (SI) in particular, in the
preparation of instrumentation standards. The Department is further aware of the benefits to
U.S.A. users of ISA standards of incorporating suitable references to the SI (and the metric
system) in their business and professional dealings with other countries. Toward this end, this
Department will endeavor tointroduce SI-acceptable metric units in all new and revised
standards to the greatest extent possible. The Metric Practice Guide, which has been published
by the Institute of Electrical and Electronics Engineers as ANSI/IEEE Std. 268-1982, and future
revisions will be the reference guide for definitions, symbols, abbreviations, and conversion
factors.
It is the policy of ISA to encourage andwelcome the participation of all concerned individuals and
interests in the development of ISA standards. Participation in the ISA standards-making
process by an individual in no way constitutes endorsement by the employer of that individual, of
ISA, or of any of the standards that ISA develops.
The information contained in the preface, footnotes, and appendices is included for information
onlyand is not a part of the standard.
The instrumentation symbolism and identification techniques described in the standard
accommodate the advances in technology and reflect the collective industrial experience gained
since the publication of Recommended Practice RP5.1 in 1949.
This revision attempts to strengthen the standard in its role as a tool of communication in the
process industries.Communication presupposes a common language; or, at the very least, it is
facilitated by one. The standard offers the foundation for that common language.
When integrated into a system, the symbols and designations presented here form a concise,
dedicated language which communicates concepts, facts, intent, instructions, and knowledge
about measurement and control systems in the process...