1、 STANDARD ISA-5.4-1991 Formerly ANSI/ISA-5.4-1991 Instrument Loop Diagrams Approved 9 September 1991 Copyright g227 1991 by the Instrument Society of America. All rights reserved. Printed in the UnitedStates of America. No part of this publication may be reproduced, stored in a retrieval system, ort
2、ransmitted in any form or by any means (electronic, mechanical, photocopying, recording, orotherwise), without the prior written permission of the publisher.ISA67 Alexander DriveP.O. Box 12277Research Triangle Park, North Carolina 27709ISA-5.4-1991Instrument Loop DiagramsISBN 978-1-55617-227-4ISA-5.
3、4-1991 3PrefaceThe information contained in the Preface and Forward is for information only and is not a part of the standard.This standard is 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,
4、but must be subject to periodic review. Toward this end, the Society welcomes all comments and criticisms, and request 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) 549-8411, e-mail:
5、 standardsisa.org.The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units 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
6、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 try to introduce SI-acceptable metric units in all new and revised standards to the greatest
7、 extent possible. The Metric Practice Guide, 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 and welcom
8、e 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 employers of the individual, of the ISA, or of any of the standards that ISA develops.At the
9、 time it approved this standard revision, the ISA-SP5.4 Committee had the following members:NAME COMPANYW. Richard Shaw Stearns Roger*Gerald V. Barta Dow Corning CorporationWilliam H. Cleary Stone & WebsterRichard L. Emerson Bechtel Power CorporationEdward E. Olinek Stearns Roger*Raymond Robertson P
10、PGRobert P. Larkin Ford, Bacon & DavisJ. Slavin Delmar ControlsJohn Lorenz Leeds & NorthrupRichard E. Terhune ConsultantMike Wiley Lummus CrestThomas C. McAvinew Metropolitan Denver Sewage Disposal District*One vote4 ISA-5.4-1991This recommended practice was approved for publication by the ISA Stand
11、ards and Practices Board in 1989.NAME COMPANYD. Bishop, Vice-President Chevron U.S.A. Inc.N. Conger Fisher Controls Intl. Inc.C. Gross Eagle TechnologyH. Hopkins Utility Products of ArizonaR. Jones Dow Chemical CompanyA. McCauley Chagrin Valley Controls, Inc.E. Nesvig ERDCO Engineering Corp.R. Presc
12、ott Moore Products CompanyD. Rapley Rapley Engineering ServiceR. Reimer Allen-Bradley CompanyJ. Rennie Factory Mutual Research CorporationW. Weidman Gilbert/Commonwealth, Inc.J. Whetstone National Inst. of Standards & TechnologyM. Widmeyer The Power Supply SystemP. Bliss* ConsultantW. Calder III* Th
13、e Foxboro CompanyB. Christensen* ConsultantL. Combs* ConsultantR. Galley* ConsultantT. Harrison* Florida State UniversityR. Jones* Philadelphia Electric CompanyR. Keller* ConsultantO. Lovett* ConsultantE. Magison* Honeywell, Inc.R. Marvin* ConsultantW. Miller* Moore Products CompanyJ. Mock* Bechtel
14、Western Power CorporationG. Platt* ConsultantJ. Williams* Stearns Catalytic Corporation*Director EmeritusISA-5.4-1991 5ForewordInstrument loop diagrams are suitable for general use throughout industry. It is important to consider their value for design, construction, checkout, start-up, operation, m
15、aintenance, rearrangement, and reconstruction. Benefits can include reduction in engineering costs, improved loop integrity and purchasing accuracy, and easier maintenance troubleshooting.An instrument loop diagram can be effective on any size project from one or two loops up to large and complex in
16、stallations. It can present on one sheet all the information or references to the information needed for installation, checkout, start-up and maintenance. Without the use of an instrument loop diagram, that information is spread among many other documents and is not readily available. Updating this
17、single diagram to “as built“ status is more easily achieved than updating the variety of other documents.This standard does not mandate the style and content of instrument loop diagrams, but rather it is a consensus concerning their generation. As such, it has the same strengths and weaknesses as ot
18、her consensus standards. Its primary strength is that the format and content guidelines apply to the majority of instrumentation applications. Its weakness is that it is not specific enough to satisfy the special requirements of particular interest groups.The ISA Standards Committee on Instrument Lo
19、op Diagrams operates within the ISA Standards and Practices Department. This committee is appreciative of the work of previous SP5.4 committees and has tried to treat their work with respect. This committee would like to acknowledge the work of the SP5.1 committee in developing ISA-5.1, Instrumentat
20、ion Symbols and Identification. One of our major goals has been to have the ISA 5.4 standard conform to the revised 5.1 standard.ISA-5.4-1991 7Contents1Purpose .92 Scope . 93 Applications 93.1 Serve many purposes. 93.2 Design . 93.3 Construction 93.4 Start-up 103.5 Operation . 103.6 Maintenance 103.
21、7 Modification . 104 Definitions . 105 Content 106 Format 127 Symbols . 127.1 Instrument connection and action information . 127.2 General terminal or bulkhead symbol 137.3 Instrument terminals or ports . 137.4 Instrument system energy supply 137.5 Identification of instrument action 148 Examples .
22、14ISA-5.4-1991 91 Purpose1.1 Provide guidelines. This standard will provide guidelines for the preparation and use of instrument loop diagrams in the design, construction, start-up, operation, maintenance, and mod-ification of instrumentation systems.1.2 Assist understanding. This standard will assi
23、st the understanding of instrument loop dia-grams and improve communications among technical, non-technical, management, design, con-struction, operating, and maintenance personnel.2 Scope2.1 Additional information for individual loop. This standard establishes minimum required information and ident
24、ifies additional optional information for a loop diagram for an individual instru-mentation loop. This loop is typically part of a process depicted on the class of engineering drawings referred to as Piping and Instrument Drawings (P&IDs).2.2 Suitability. This standard is suitable for use in the che
25、mical, petroleum, power generation, air conditioning, metal refining, and many other industries.2.3 Specialty fields. Certain fields, such as astronomy, navigation, and medicine, use very specialized instruments that are different from the conventional industrial process instruments. No specific eff
26、ort to have this standard meet the requirements of those fields has been made. However, this standard is flexible enough to meet many of the needs of specialty fields.3 Applications3.1 Serve many purposes. Loop diagrams serve many purposes. Several of these stated below are in the chronology of proj
27、ect development.3.2 Design1) Illustrate control philosophy and confirm the completeness of submitted data2) An extension of P&IDS, which show the components and accessories of the instrument loop, connections between devices, and identification of component action3) The specification of instrument h
28、ardware items and a means of communicating requirements to vendors3.3 Construction1) Panel instrumentation interconnections and checkout diagram10 ISA-5.4-19912) Instrumentation installation references and special requirements3) Instrumentation interconnections4) Instrumentation loop checkout5) Insp
29、ection and documentation3.4 Start-up1) Pre-start-up commissioning and calibration2) Training tool and aid3.5 Operation1) Communication medium between operations, maintenance, and engineering personnel2) Training device for operations3.6 Maintenance1) Troubleshooting2) Routine calibration3) Preventat
30、ive and corrective maintenance tool3.7 Modification1) Rearrangement2) Reconstruction3) Enhancement4 DefinitionsThis standard is an extension of the communications defined by ISA-5.1, “Instrumentation Symbols and Identification”, and the definitions of that standard therefore apply. The guidelines of
31、 this standard cover the content of a loop diagram drawing, and it does not produce any new definitions for that presentation process.5 Content5.1 General. The instrument loop diagram is a composite representation of instrument loop information. It contains all associated electrical and piping conne
32、ctions and should contain all of the information needed to accommodate the intended uses. Classified below are minimum require-ments and some established options that can be used to match the desired uses.ISA-5.4-1991 115.2 Minimum content requirements. As a minimum, an instrument loop diagram shall
33、 contain the information covered below.1) Identification of the loop and loop components shown on the P&IDS. Other principal components of the loop to be shown and identified under ISA-5.1, “Instrumentation Symbols and Identification”.2) Word description of loop functions within the title. If not ad
34、equate, use a supplemental note. Identify any special features or functions of shutdown and safety circuits.3) Indication of the interrelation to other instrumentation loops, including overrides, interlocks, cascaded set points, shutdowns and safety circuits.4) All point-to-point interconnections wi
35、th identifying numbers or colors of electrical cables, conductors, pneumatic multitubes, and individual pneumatic and hydraulic tubing. This identification of interconnections includes junction boxes, terminals, bulkheads, ports, and grounding connections.5) General location of devices such as field
36、, panel, auxiliary equipment, rack, termination cabinet, cable spreading room, I/0 cabinet, etc.6) Energy sources of devices, such as electrical power, air supply, and hydraulic fluid supply. Identify voltage, pressure, and other applicable requirements. For electrical sources, identify circuit or d
37、isconnect numbers.7) Process lines and equipment sufficient to describe the process side of the loop and provide clarity of control action. Include what is being measured and what is being controlled.8) Actions or fail-safe positions (electronic, pneumatic, or both) of control devices such as contro
38、llers, switches, control valves, solenoid valves, and transmitters (if reverse-acting). These are to be identified in accordance with ISA-5.1, “Instrumentation Symbols and Identification”.5.3 Optional content information. Additional information needs to be considered for its effec-tiveness in accomm
39、odating the intended uses. Stated below are typical examples of items for inclusion at the users discretion.1) Process equipment, lines, and their identification numbers, source, designation, or flow direction.2) Reference to supplementary records and drawings, such as installation details, P&IDs, l
40、ocation drawings, wiring diagrams or drawings, and instrument specifications.3) Specific location of each device, such as elevation, area, panel subdivision, rack or cabinet number and location, I/O location, etc.4) Cross reference between loops that share a common discrete component, such as multip
41、en recorders, dual indicators, etc.5) References to equipment descriptions, manufacturers, model numbers, hardware types, specifications or data sheets, purchase order numbers, etc.6) Signal ranges and calibration information, including setpoint values for switches, and alarm and shutdown devices.7)
42、 Software reference numbers, such as I/O addresses, control block types and names, network interfaces, point names, etc.8) Engraving or legend information that helps identify the instrument or accessory.12 ISA-5.4-19919) Accessories, tagged or otherwise identified, such as regulators, filters, purge
43、 meters, manifold valves, root valves, etc.10) References to manufacturers documentation such as schematics, connection details, operating instructions, etc.11) Color code identification for conductors or tubes that use numbers for differentiation.6 Format6.1 Consistency for ease of use. The followi
44、ng format conventions should be consistently employed for improved communications and ease of use.6.2 Size of drawing. The minimum size for the original drawing should be 11 inches X 17 inches. Attention to the proper size of text and symbols will keep them legible on reduced copies. (For convenienc
45、e in printing and binding, this standard uses reduced size example figures.)6.3 Drawing content. An instrument loop diagram should typically contain only one loop. Avoid showing a loop on multiple pages or sheets where practical. Use judgment to accommodate the individual situations where loops that
46、 share common components can be adequately and com-pletely communicated on a single diagram. Prevent overcrowding and provide space for future additions and loop data.6.4 General layout. Maintain a consistent layout (horizontal or vertical) throughout a project. A suggested layout is to divide the d
47、rawing into sections for relative locations of devices.7 Symbols7.1 Instrument connection and action information. The symbols in ISA-5.1 apply for instrument loop diagrams. However, expansion of those symbols to include connection points, energy source (electrical, air, hydraulic), and instrument ac
48、tion is necessary to provide the information required on instrument loop diagrams.NOTE: The terminals or ports shown are not to be pictorial.ISA-5.4-1991 137.2 General terminal or bulkhead symbol7.3 Instrument terminals or ports7.4 Instrument system energy supply7.4.1 Electrical power supply. Identi
49、fy electrical power supply followed by the appropriate supply level identification and circuit number or disconnect identification.7.4.2 Air supply. Identify air supply followed by air supply pressure.14 ISA-5.4-19917.4.3 Hydraulic fluid supply. Identify hydraulic fluid followed by the fluid supply pressure.7.5 Identification of instrument action. Show the direction of the instrument signal by placing appropriate letters close to the instrument bubble. Identify an instrument in which the value of the output signal increases or changes to its maximum value, as input (measured variable) incr
