1、Specification Forms forProcess Measurement andControl Instruments, PrimaryElements, and Control ValvesApproved 30 October 1981ISA201981 FormerlyISAS201981STANDARDISA The Instrumentation,Systems, andAutomation Society TMCopyright 1981 by the Instrument Society of America. All rights reserved. Printed
2、 in the UnitedStates of 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
3、12277Research Triangle Park, North Carolina 27709ISA-20-1981, Specification Forms for Process Measurement and Control Instruments, Primary Elements and Control ValvesISBN 0-87664-347-0ISA-S20-1981 3PrefaceThis Preface is included for information purposes and is not part of ISA-20-1981.This Standard
4、has been prepared as a part of the service of the ISA toward a goal of uniformity in the field of instrumentation. To be of real value this report should not be static, but should be subjected to periodic review. Toward this end the Society welcomes all comments and criticisms, and asks that they be
5、 addressed to the Standards and Practices Board Secretary, ISA, 67 Alexander Drive, P.O. Box 12277, Research Triangle Park, North Carolina 27709, Telephone (919) 549-8411, Fax (919) 549-8288, e-mail: standardsisa.org.This document was prepared by the Subcommittee on Instrument Specification Forms (R
6、P20.1) and was originally published in 1956 under the direction of G. G. Gallagher of the Fluor Corporation. In 1961 additional forms were published, prepared by Committee 8D-RP20 under the direction of W. Carmack of the Fluor Corporation. This revision was prepared, with the supervision of the Chai
7、rman, R. E. Frey of Rohm and Haas Company, by the committee as listed below.SP20 COMMITTEENAME COMPANYR. E. Frey (deceased) Rohm and Haas CompanyW. S. Buzzard Fisher and Porter CompanyJ. G. Converse Sun Oil CompanyG. F. Erk Sun Oil CompanyJ. Imber Atlantic Richfield CompanyR. D. Irwin Honeywell, Inc
8、.E. F. Kremer E. I. duPont deNemours width x height.4) It is assumed that the instrument has its own case or shelf suitable for single mounting, unless “MULTICASE“ is checked. Shelf or separable case for multiple case mounting instrument is not included unless listed and described as an accessory.5)
9、 Enclosure class refers to composite instrument. If electrical contacts are the case they must meet this classification inherently or by reason of the enclosure. Use NEMA identification system or ISA system RP8.1.6) Specify electrical power to the entire instrument from an external source.7) For mul
10、tiple instruments list ranges on secondary sheet, but specify other chart options on primary sheet. Chart graduations assumed to be uniform unless otherwise noted. Circular charts assumed to have 24 hr/revolution speed; strip charts 3/4 in. to 1 in. per hour.8) Chart drive mechanism assumed to be sy
11、nchronous motor operating on 117V 60 Hz and suitable for ENCLOSURE CLASS specified on line 5. If the chart drive is pneumatic so state identify pneumatic pulser under options. Note deviations from standard (MFR) under notes, i.e., dual speed or special speeds.9) The scale type may be SEGMENTAL, VERT
12、ICAL, HORIZONTAL, DIAL (CIRCULAR) or other. Ranges 1, 2, 3 and 4 are used for multiple inputs. The first listed (No. 1) is assumed to be the controller input, if a controller is used.10) See explanation of terminology given on specification sheet. For further definition refer to American National St
13、andard C85.1-1963, “Terminology for Automatic Control.“ Specific ranges of control modes can be listed after “OTHER,“ if required.11) For multiple items specify on second sheet.12) If standard auto-manual switching is not known or not adequate, specify particular requirements, such as BUMPLESS, PROC
14、EDURELESS, 4-POSITION, or as required.13) Remote set point adjustment assumes full adjustment range. Specify limits if required. Under other can be noted bias or ratio.14) Specify if applicable.15) Specify if applicable.16) All input signals on multi-channel instruments assumed to be the same range
15、unless otherwise noted.17) Specify number of inputs.18) Check if power source for the loop is contained in this instrument or in some external instrument.ISA-S20-1981 1319) Form may be SPST, SPDT, DPDT or other. Rating refers to electrical rating of switch or contacts in amps.20) Specify if alarm is
16、 actuated by measured variable or by deviation from controller set point. Give contact action if single throw form.21) Specify required accessories and options, fill in number of charts. This is assured to be number of chart rolls for strip charts.22) After selection is made fill in manufacturer and
17、 specific model number.SECONDARY SHEET for listing multiple instruments. List all instruments of the same type specified on the primary sheet, with variations as shown. “Notes” refers to notes listed by number at the bottom of the sheet. Line 11 of sheet 1a is tabulated under measurement increases,
18、output tabulate increase or decrease.14 ISA-S20-1981ISA-S20-1981 15ISA Form S20.2b16 ISA-S20-19814 AnnunciatorsInstructions for ISA Forms S20.2a and 20.2b1) Write in Tag Number of entire Annunciator system.2) Omit if single unit.3) Specify cabinet mounting.4) Specify type of cabinet.5) Refers only t
19、o display and audible.6) Specify power supply required.7) Check WHITE TRANSLUCENT, or write in color of plate and engraving required. Specify window size in height x width.8) Number of independent displays in one box, or position in cabinet.9) If individual bullseyes, specify number and color requir
20、ed. If self-contained unit, specify number of normal and off-normal lights and color of each. (Example two red independent off-normal and one green common normal light.)10) Describe display if other than blacklighted nameplate or bullseye. For example; Blacklighted prism, Electrolumenescent, Two-col
21、or pneumatically operated.11) Specify type of logic unit which operates display and audible system.12) Check required location of logic components.13) Check Enclosure Class of logic components and or enclosure. General purpose relays inside an explosion proof housing, or explosion proof relays will
22、both satisfy the hazardous area classification. Use NEMA identification system or ISA system RP8.1.14) Specify voltage across contacts which actuate alarm.15) Give contact action.16) Sequential Alarm refers to “First Out“ system.17) Specify type of ring back, if applicable.18) An operational test ac
23、tuates audible as well as lamps.19) Specify flasher location and model number.20) Specify type of Acknowledgment, and Pushbutton locations.21) Specify reset and pushbutton location.22) Write in ISA Sequence number as described in RP18.1, Specifications and Guides for the Use of General Purpose Annun
24、ciators, or fill in the table for the sequence required.23) Write in the model number, or describe type, if required.24) Write in the model number, or describe type, if required.ISA-S20-1981 1725) Write in the model number, or describe type, if required.26) Specify number required, and color.27) Spe
25、cify power supply location, i.e., in logic cabinet, or separate cabinet.28) For any additional accessories required.29) Fill in after selection is made.18 ISA-S20-1981ISA-S20-1981 1920 ISA-S20-1981ISA-S20-1981 2122 ISA-S20-1981ISA-S20-1981 235 Potentiometer instruments specification sheet instructio
26、nsInstructions for ISA Forms S20.10a and 20.10bPrefix number designates line number on corresponding specification sheet.1) To be used for single item. Use secondary sheet for multiple listing.2) Check as many as apply.3) Check one. Note that sheet may be used to specify galvanometric type of instru
27、ment.4) Nominal size refers to approximate front of case dimensions; width x height.5) It is assumed that the instrument has its own case or shelf suitable for single mounting unless “multi-case“ is checked. Shelf or separable case for multiple case mounting instrument is not included in this sheet
28、unless listed as an accessory.6) Enclosure Class refers to composite instrument. If electrical contacts are in the case, they meet this rating inherently or by reason of the enclosure. Use NEMA identification system or ISA system presented in RP8.1.7) Specify electrical power to entire instrument.8)
29、 For multiple instruments list ranges on second sheet, but specify other items here.9) Ranges 1 and 2 refer to multi-channel instruments. The first listed is assumed to be the controller input (if any).10) For multiple items list number of points on second sheet. “Point Select“ permits by-passing an
30、y or all points by a switching mechanism.11) For multiple items show number of switches on second sheet under “No. of Points.“12) Specify if applicable.13) See explanation of terminology given on spec. sheet. Specific ranges of control modes can be listed under “other“ if required.14) For multiple i
31、tems specify on second sheet.15) If standard auto-manual switching is not known or not adequate, specify particular requirements, such as BUMPLESS, PROCEDURELESS, 4-POSITION, or as required.16) Remote set point adjustment assumes full adjustment range. Specify limits if required.17) Specify if appli
32、cable.18) Specify if applicable.19) Check if thermocouple input applies. Lead resistance required only for galvanometer.20) Specify any input other than thermocouple. “Calibration“ refers to curve used and does not imply that element is specifically calibrated for this instrument.21) Form may be SPS
33、T, SPDT, DPDT, etc. Rating is electrical rating of switch in amps.24 ISA-S20-198122) Check if alarm is actuated by measured variable or by deviation from controller set point. Give contact action if single throw form. Specify calibrated or blind alarm index setter.23) Specify if applicable.24) Speci
34、fy if applicable.25) Accessories for multiple items may be covered by “notes“ second sheet.26) May be filled in after selection is made.SECONDARY SHEET for listing multiple instruments. List all instruments of the same type, specified on Primary Sheet, with variations as shown. “Notes“ refers to not
35、es listed by number at the bottom of the sheet. Or use Secondary Sheet to list and identify the multiple points of a single multipoint instrument.ISA-S20-1981 2526 ISA-S20-1981ISA-S20-1981 276 Temperature instruments (filled systems)Instructions for ISA Forms S20.11a and 20.11b1) To be used for a si
36、ngle item. Use secondary sheet for multiple listing.2) Check as many as apply.3) Nominal size refers to approximate front of case dimensions; width x height.4) Yoke refers to a bracket designed for mounting the instrument on a pipe stand.5) Enclosure class refers to composite instrument. If electric
37、al contacts are in the case, they must meet this classification inherently or by reason of enclosure. Use NEMA identification or ISA identification RP8.1.6) Specify electrical power to the entire instrument from an external source.7) Specify chart size, range and number if applicable.8) Chart drive
38、mechanism assumed to be synchronous motor operating in 117V 60 Hz and suitable for ENCLOSURE CLASS specified on line 5. If the chart drive is pneumatic so state identify pneumatic pulser under options. Note deviations from standard (MFR) under notes, i.e., dual speed or special speeds.9) The scale t
39、ype may be SEGMENTAL, VERTICAL, HORIZONTAL, DIAL (CIRCULAR) or other. Ranges 1, 2, 3 and 4 are used for multiple inputs. The first listed (No. 1) is assumed to be the controller input, if a controller is used.10) Specify transmitter output if applicable.11) See explanation of terminology given on sp
40、ecifications sheet. For further definition refer to American National Standard C85.1-1963, “Terminology for Automatic Control.“ Specific ranges of control modes can be listed after “OTHER,“ if required.12) For multiple items specify on second sheet.13) If standard auto-manual switching is not known
41、or not adequate, specify particular requirements, such as BUMPLESS, PROCEDURELESS, 4-POSITION, or as required.14) Remote set point adjustment assumes full adjustment range. Specify limits if required.15) Specify if applicable.16) Specify if applicable.17) Filled thermal systems can be of the followi
42、ng SAMA classifications:Class IA: Liquid filled, uniform scale, fully compensated.Class IB: Liquid filled, uniform scale, case compensated only.Class IIA: Vapor pressure, non-linear scale with measured temperature abovecase and tubing temperature.Class IIB: Vapor pressure, non-linear scale with meas
43、ured temperature belowcase and tubing temperature.28 ISA-S20-1981Class IIC: Vapor pressure, non-linear scale with measured temperature aboveand below case and tubing temperature.Class IIIA: Gas filled, uniform scale, fully compensated.Class IIIB: Gas filled, uniform scale, case compensated only.Clas
44、s VA: Mercury filled, uniform scale, fully compensated.Class VB: Mercury filled, uniform scale, case compensated only.19) Range refers to process input span for which an output is desired. Adjustable range means that the unit can give its normal output over a range of inputs.20) Bulb type can be pla
45、in, averaging, rigid, adjustable union connections, fixed union connection. Capillary extension length can be rigid or flexible, etc.21) Capillary tube specifications22) Well Specifications23) Form may be SPST, SPDT, DPDT, etc. Rating is electrical rating of switch in volt amps.24) Check if alarm is to be actuated by measured variable or by deviation from controller set point. Give contact action if single throw from.ISA-S20-1981 2930 ISA-S20-1981
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