ISA 7 0 01-1996 Quality Standard for Instrument Air《仪表气源的质量标准》.pdf

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1、Quality Standard forInstrument AirApproved 12 November 1996ANSI/ISA 7.0.01 1996Formerly ANSI/ISAS 7.0.01 1996AMERICAN NATIONAL STANDARDISA The Instrumentation,Systems, andAutomation Society TMCopyright g227 1996 by the Instrument Society of America. All rights reserved. Printed in the UnitedStates o

2、f America. No part of this publication may be reproduced, stored in a retrieval system, ortransmitted 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

3、 Park, North Carolina 27709ANSI/ISA-7.0.01-1996, Quality Standard for Instrument AirISBN: 1-55617-606-6ANSI/ISA-7.0.01-1996 3PrefaceThis preface, as well as all material contained in the footnotes and annexes, is included for information purposes and is not part of the ANSI/ISA-7.0.01-1996.This Stan

4、dard has been prepared as a part of the service of ISA, the international society for measurement and control, 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 to periodic review. Toward this end, the Society w

5、elcomes 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) 549-8411; Fax (919) 549-8288; E-mail: standardsisa.org.The ISA Standards and Practices Depar

6、tment 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, recommended practices, and technical reports. The Department is further aware of the benefits to USA u

7、sers 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 to introduce SI and acceptable metric units as optional alternatives to English units in all n

8、ew and revised standards, recommended practices, and technical reports to the greatest extent possible. The Metric Practice Guide, which has been published by the Institute of Electrical and Electronics Engineers as ANSI/IEEE Standard 268-1982, and future revisions, will be the reference guide for d

9、efinitions, symbols, abbreviations, and conversion factors. SI (metric) conversions in this Standard are given only to the precision intended in selecting the original numerical value. When working in SI units, the given SI value should be used; when working in customary U.S. units, the given U.S. v

10、alue should be used.It is the policy of ISA to encourage and welcome the participation of all concerned individuals and interests in the development of ISA standards, recommended practices, and technical reports. Participation in the ISA standards-making process by an individual in no way constitute

11、s endorsement by the employer of that individual, of ISA, or of any of the standards that ISA develops.This Standard, complete with all updates, incorporates the following previous SP7 Subcommittees and documents:SP7.1 Pneumatic Control Circuit Pressure TestSP7.3 Air Quality Standards for Pneumatic

12、InstrumentsSP7.3 Application and Tests for Quality Standards for Instrument AirSP7.4 Air Pressures for Pneumatic Controllers and Transmission SystemsSP7.6 Pneumatic Control Circuit Transmission DistancesISA-RP7.1-1956 Pneumatic Control Circuit Pressure TestISA-7.3-1975 (R1981) Quality Standard for I

13、nstrument AirISA-7.4-1981 Air Pressures for Pneumatic Controllers, Transmitters and Transmission SystemsISA-RP7.7-1984 Producing Quality Instrument Air4 ANSI/ISA-7.0.01-1996The following people served as members of ISA Committee SP7:NAME COMPANYD. Hendrick, Chairman Consultant C. Parry, Co-Chairman

14、Pacific Gas b) to provide limits for entrained particle size and oil content in instrument quality air;c) to establish an awareness of possible sources of corrosive or toxic contamination entering the air system through the compressor suction, plant air system cross connection, or instrument air con

15、nections directly connected to processes;d) to establish standard air supply pressures (with limit values) and operating ranges for pneumatic devices;e) to specify ranges of pneumatic transmission signals used in measurement and control systems between elements of systems. It includes, but is not li

16、mited to, the following:1) Pneumatic controllers2) Pneumatic transmitters and information transmission systems3) Current-to-Pressure transducers4) Pneumatic control loops; andf) to establish criteria for testing compliance with instrument-quality air standards.2 PurposeThe purpose of this Standard i

17、s to establish a standard for instrument quality air.3 Definitions3.1 ambient temperature: The temperature of the medium surrounding a device.3.2 dew point temperature: The temperature, referred to at a specific pressure, at which water vapor condenses.10 ANSI/ISA-7.0.01-19963.3 elements of measurem

18、ent and control systems: Functional units or integrated combinations thereof that ensure the transducing, transmitting, or processing of measured values, control quantities or variables, and reference variables. A valve actuator in combination with a current to pressure transducer, valve positioner,

19、 or a booster relay is considered an element that receives the standard pneumatic transmission signal or standard electric current transmission signal.3.4 instrument quality air: Air, which is the working media for various devices, that has been treated to minimize liquid and particulate matter. NOT

20、E Some individual devices may require further conditioning of the air (filtration, dehumidification) to ensure reliable operation.3.5 lower limit: The lowest value of the measured variable that a device can be adjusted to measure.3.6 measured value: The numerical quantity resulting, at the instant u

21、nder consideration, from the information obtained by a measuring device.3.7 micrometer (m): A metric measure with a value of 10-6meters or 0.000001 meter (previously referred to as “micron“).3.8 parts per million (ppm): Represents parts per million and should be given on a weight basis. The abbrevia

22、tion shall be ppm (w/w). If inconvenient to present data on a weight basis (w/w), it may be given in a volume basis; (v/v) must be stated after the term ppm; e.g., 5 ppm (v/v) or 7 ppm (w/w).3.9 pneumatic controller: A device that compares the value of a variable quantity or condition to a selected

23、reference and operates by pneumatic means to correct or limit the deviation.3.10 pneumatic transmission system: A system that develops an output directly corresponding to the input information for conveying informationcomprising a transmitting mechanism that converts input information into a corresp

24、onding air pressure, interconnecting tubing, and a receiving element responsive to air pressure.3.11 pressure dew point: The dew point value at line pressure of the compressed air system (usually measured at the outlet of the dryer system or at any instrument air supply source prior to pressure redu

25、ction). When presenting or referencing dew point, the value shall be given in terms of the line pressure; e.g., -40C (-40F) dew point at 690 kPa (approximate) (100 psig).3.12 range of a pneumatic transmission signal: The range determined by the lower and upper limit of the signal pressure.3.13 relat

26、ive humidity: The ratio (expressed as a percentage) of the partial pressure of water vapor contained in the air at a given temperature and pressure to the maximum partial pressure of water vapor that could be present at the same temperature under saturated conditions.3.14 span: The algebraic differe

27、nce between the upper and lower range values.3.15 supply pressure: The pneumatic supply pressure that enables the system element to generate the pneumatic transmission signals specified to provide the final device with required operational force.3.16 upper limit: The highest value of the measured va

28、riable that a device can be adjusted to measure.ANSI/ISA-7.0.01-1996 114 Instrument air system designThe specifications for instrument air systems vary in order to meet a range of application requirements. This makes the specification of any specific design requirements impractical, but in general,

29、a properly designed instrument air system shoulda) provide a sufficient quantity of air to supply the highest anticipated load plus margin for future growth including leakage;b) provide the quality air required by the user; andc) provide for maintenance and testing of the system.5 Instrument air, qu

30、ality standardThis Standard establishes four elements of instrument air quality for use in pneumatic instruments (see Annex B.2).5.1 Pressure dew pointThe pressure dew point as measured at the dryer outlet shall be at least 10C (18F) below the minimum temperature to which any part of the instrument

31、air system is exposed. The pressure dew point shall not exceed 4C (39F) at line pressure. A monitored alarm is preferred; however, if a monitored alarm is unavailable, per shift monitoring is recommended. See Annex B.2.1. See Table B-1, Note 3 when using a refrigerant dryer.5.2 Particle sizeA maximu

32、m 40 micrometer particle size in the instrument air system is acceptable for the majority of pneumatic devices. Pneumatic devices that require instrument air with less than 40 micrometer particle sizes shall have additional filtration to meet the particulate size limit for the device.Subsequent to a

33、ny maintenance or modification of the air system, maximum particle size in the instrument air system should be verified to be less than 40 micrometers.12 ANSI/ISA-7.0.01-19965.3 Lubricant contentThe lubricant content should be as close to zero as possible, and under no circumstances shall it exceed

34、one (1) ppm w/w or v/v. Any lubricant in the compressed air system shall be evaluated for compatibility with end-use pneumatic devices. For example, the use of automatic oilers is strongly discouraged.* 5.4 ContaminantsInstrument air should be free of corrosive contaminants and hazardous gases, whic

35、h could be drawn into the instrument air supply. The air system intake should be monitored for contaminants. If contamination exists in the compressor intake area, the intake should be moved to a different elevation or location free from contamination. Some sources of contamination area) painting;b)

36、 chemical cleaning; andc) engine exhaust.*For details on why the use of automatic oilers is strongly discouraged, read the United States Nuclear Regulatory Commission Inspection Report IN 95-53 (refer to Annex A). Some cylinder-type actuators recommend a lubricant. If an in-line automatic oiler is u

37、sed in such a case, the location of the oiler must be selected to minimize the amount of the air system exposed to the lubricant. Also, the other control devices exposed to the lubricant must be of compatible material. The typical installation for an automatic oiler is at the point of use. Often the

38、 oiler is an integral part of an actuator assembly.ANSI/ISA-7.0.01-1996 13Annex A ReferencesNOTE This annex is for information purposes only and is not part of ISA-7.0.01.AMERICAN NATIONAL STANDARD INSTITUTE (ANSI)ANSI/B93.2 Fluid Power Systems and Products, 1986ANSI/B93.45M Pneumatic Fluid Power, C

39、ompressed Air Dryers, Methods for Rating and Testing, 1982ANSI/ANS-59.3 Nuclear Safety Criteria for Control Air Systems, 1992ANSI/IEEE 268 Metric Practice, 1982Available from: ANSI11 W. 42nd Street, 13th FloorNew York, NY 10036 Tel. (212) 398-0023AMERICAN PETROLEUM INSTITUTE (API) API 550 Manual on

40、Installation of Refinery Instruments and Control Systems, Fourth Edition, Part 1, Section 9, February, 1980Available from: API1220 L Street, NWWashington D.C. 20005 Tel. (202) 682-8232AMERICAN SOCIETY OF HEATING, REFRIGERATING, AND AIR CONDITIONING ENGINEERS (ASHRAE)1993 ASHRAE Handbook Fundamentals

41、, Chapters 11, 13, and 19Available from: ASHRAE1791 Tullie Circle, NEAtlanta, GA 30329-5478 Tel. (404) 636-840014 ANSI/ISA-7.0.01-1996CHEMICAL RUBBER COMPANY (CRC) Handbook of Chemistry and Physics, 75th Edition (1994-1995), Chapter 6: Fluid properties, 6.1 Thermodynamic properties of air Available

42、from: CRCCRC Press2000 Corporate Blvd. Northwest Boca Raton, FL 33431 Tel. (407) 994-0555MISCELLANEOUSCompressed Air and Gas Handbook, Fifth Edition, 1989; Published by Prentice-Hall, Inc.Compressed Gas Association, Inc., Chapter 3, Methods of Producing Compressed Air for Human Respiration.Considine

43、, D.M., Handbook of Applied Instrumentation, 1982; McGraw-Hill Book Company. Hankison, Paul M., Theory and Filtering Technique for Compressed Air Instruments, November 1953.Hehn, A.H., “Can Component Failures in Air and Oil Systems be Predicted?” Hydraulics and Pneumatics, July 1971.Lapple, C.E., “C

44、haracteristics of Particles and Particle Dispersoids,” Stanford Research Institute Journal, 1961; Stanford Research Institute, Palo Alto, CA.Queer, Elmer R. Fairmont Press, Inc., 700 Indian Trail, Lilburn, GA 30247.Weiner, Arnold L., “How to Clean and Dry Compressed Air,” Hydrocarbon Processing, Feb

45、ruary 1966; CGA Publishing, Arlington, VA.NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA, Document No. 70, Chapter 5Available from: NFPAP. O. Box 9101One Batterymarch ParkQuincy, MA 02269-9101 Tel. (617) 770-3000ANSI/ISA-7.0.01-1996 15SOCIETY OF AUTOMOTIVE ENGINEERS, INTERNATIONAL (SAE)ARP-1156 Req

46、uisites for Design Specifications for Absorptive Systems, 1969 (Revised 1992)Available from: SAE International400 Commonwealth DriveWarrendale, PA 15096-0001 Tel. (412) 776-4841UNITED STATES NUCLEAR REGULATORY COMMISSION (U. S. NRC)NRC Information Notice 95-53 Failures of Main Steam Isolation Valves

47、 as a Result of Sticking Solenoid Pilot Valves, December 1, 1995This notice is available on the World Wide Web URL:http:/www.nrc.gov/NUREG 1275 Volume 2 Air Systems Problems in U.S. Light Water Reactors, 1987Available from: U.S. NRC11555 Rockville PikeRockville, MD 20852 Tel. (301) 492-7000ANSI/ISA-

48、7.0.01-1996 17Annex B Equipment and application guidelines for producing instrument airNOTE This annex is for information purposes only and is not part of ISA-7.0.01.B.1 Instrument air system designAn instrument air supply and conditioning system consists of components required to provide an adequat

49、e volume of instrument quality air at the desired pressure.B.1.1 Instrument air supply systemTypical components of the air supply system (see Figures B-1, B-2, therefore, “unlubricated“ compressors are recommended.Although not recommended, if lubricated compressors are used, lubricant removal is required to avoid the damaging effects on air system components and end-use devices. Provisions should be made to recover lubricants for disposal in accordance with national and local environmental requirements.If synthetic oil is used to lubricate compressors, compatib