1、Specifications and Tests for Potentiometric PressureTransducersReaffirmed 29 September 1995ISA37.61982 (R1995)Formerly ISAS37.61982 (R1995)STANDARDISA The Instrumentation,Systems, andAutomation Society TMCopyright 1982 by the Instrument Society of America. All rights reserved. Printed in the UnitedS
2、tates 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 12277Research T
3、riangle Park, North Carolina 27709ISA-37.6-1982 (R1995), Specifications and Tests for Potentiometric Pressure TransducersISBN 0-87664-380-2ISA-S37.6-1982 (R1995) 3PrefaceThis preface, as well as all footnotes and annexes, is included for information purposes and is not part of ISA-37.6-1982 (R1995).
4、This standard has been prepared as a part of the service of ISA, the international society for measurement and control, toward the 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, t
5、he 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) 549-8411; Fax: (919) 549-8288; E-mail: standardsisa.org.The ISA Standards and P
6、ractices 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, recommended practices, and technical reports. The Department is further aware of the ben
7、efits to USA 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 to introduce SI-acceptable metric units in all new and revised standards to the
8、greatest extent possible. The Metric Practice Guide, which has been published by the Institute of Electrical and Electronics Engineers as ANSI/IEEE Std. 268-1992, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors.It is the policy of ISA
9、 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 constitutes endorsement by the employer of that indiv
10、idual, of ISA, or of any of the standards which ISA develops.This Standard is intended as a guide for technical personnel at user facilities as well as by manufacturers technical and sales personnel whose duties include specifying, calibrating, testing or showing performance characteristics of poten
11、tiometric pressure transducers. By basing users specifications as well as technical advertising and reference literature on this Standard, or by referencing portions thereof, as applicable, a clear understanding of the users needs or of the transducers performance capabilities, and of the methods us
12、ed for evaluating or proving performance, will be provided. Adhering to the specification outline, terminology and procedures shown will not only result in simple, but also complete specifications; it will also reduce design time, procurement lead time, and labor, as well as material costs. Of major
13、 importance will be the reduction of qualification tests resulting from use of a commonly accepted test procedure and uniform data presentation.The development of this Standard was initiated as the result of a survey conducted in December, 1960. A total of 240 questionnaires was sent out to transduc
14、er users and manufacturers. A strong majority indicated in their replies a need for transducer standardization. As potentiometric pressure transducers were one of the types shown to be most in need of standardization, a project subcommittee, SP37.6, Potentiometric Pressure Transducers, was formed un
15、der the cognizance of Committee SP37, Transducers for Aerospace Testing, and a standard was developed and published in 1967. Subsequently, the standard was reviewed extensively, and revised in 1974. The reviewers were selected from a broad cross-section of all industries and sciences in which transd
16、ucers are applied for measuring purposes.4 ISA-S37.6-1982 (R1995)The following individuals served on the 1969 SP37 committee:NAME COMPANYP. S. Lederer, Chairman National Bureau of StandardsJ. F. Mayo-Wells National Bureau of StandardsR. R. Bouche ENDEVCOH. C. Chandon Rosemount, Inc.J. Hilten Nationa
17、l Bureau of StandardsH. N. Norton Jet Propulsion LaboratoryJ. J. Elengo Revere Corporation of AmericaO. C. Ingebritsen NASA/Langley Research CenterR. D. Bronson Lockheed Electronics CompanyJ. Z. Inskeep Jet Propulsion LaboratoryThe following individuals served on the ISA Committee SP37, who reaffirm
18、ed ISA-S37.5 in 1995:NAME COMPANYE. Icayan, Chairman Westinghouse Hanford Co.J. Weiss Electric Power Research Inst.P. Bliss, Deceased ConsultantM. Brigham The Supply SystemD. Hayes LA Dept. Water e.g., psia for absolute pressure in psi. In the interim it is recommended that for the SI system, the ty
19、pe of pressure be indicated in this manner: “. . . An absolute pressure of _Pa.“ “. . . A differential pressure range of _ kPa,“ etc.2. For differential pressure transducers, the allowable range of reference pressures shall be listed; e.g., “0 to 1MPa“ or “0 to 100 psi.“4.1.1.2 Measured fluids*The f
20、luids in contact with pressure port(s) shall be listed; e.g., nitric acid, liquid oxygen. Requirements for and limitations on the isolating element (if used) shall be listed.4.1.1.3 Configuration and dimensionsThe outline drawing shall show the configuration with dimensions in millimeters (inches).
21、Unless pressure and electrical connections are specified (reference 4.1.1.5 and 4.1.3.4), the outline shall include limiting maximum dimensions for these connections.4.1.1.4 Mountings and mounting dimensionsUnless the pressure connection serves as a mounting, the outline drawing shall indicate the m
22、ethod of mounting with hole size, centers, and other pertinent dimensions in millimeters (inches), including thread specifications for threaded holes, if used.4.1.1.5 Pressure connectionThe pressure connection(s) shall be indicated on the outline drawing. For threaded fittings, specify Applicable Mi
23、litary or Industry standards or nominal size, number of threads per millimeter (threads per inch), thread series, and thread class. For hose tube fitting, specify tube size.4.1.1.6 Mounting effectsThe maximum mounting force or torque shall be specified if it will tend to affect transducer performanc
24、e (reference 4.2.28).4.1.1.7 MassThe mass of the transducer shall be specified to grams (ounces).4.1.1.8 Case sealingIf case sealing is necessary, the mechanism and materials used for sealing should be described. The same requirement applies to the electrical connector. The resistance of the sealing
25、 materials to cleaning solvents and commonly used measured fluids should be stated.4.1.1.9 IdentificationThe following characteristics shall be permanently inscribed on the outside of the transducer case or on a suitable nameplate permanently attached to the case.a) Nomenclature of transducer (accor
26、ding to Section 3 of ISA-S37.1)*Defined in ISA-S37.112 ISA-S37.6-1982 (R1995)b) Name of Manufacturer, (Part number to reflect one controlled configuration), and Serial Numberc) Range* in Pa (psi) and designation of type of pressure (see 4.1.1.1). Maximum excitation*d) Transduction element resistance
27、* (Potentiometric Element)e) Identification of Measured and Reference Ports* (for differential pressure transducers)f) Reference Pressure Range* (for differential pressure transducers)g) Identification of Electrical Connectionsh) Inscription of the following characteristics is optional:i) Customer S
28、pecification or Part Number or bothj) Type of Electrical Connector and Mating Connector (if applicable)k) Operating Temperature Range*l) Proof Pressure*NOTE Identification of Pressure Ports may be abbreviated MEAS e.g.,a) diaphragm (flat or corrugated)*;b) capsule*;c) bellows*; andd) bourdon tube* -
29、 “C“ or “U“ shaped, spiral, helical, or twisted.NOTE Where used, an isolating element with transfer fluid shall be detailed as to composition.4.1.2.3 Damping fluidWhere used, the type, composition, temperature characteristics, and compatibility with transducer components shall be specified.*Defined
30、in ISA-S37.1*Defined in 4.3ISA-S37.6-1982 (R1995) 134.1.2.4 Number of potentiometric elements* or taps*Where more than one potentiometric transducer element or a tapped element is required, they shall be specified.4.1.2.5 Dead volumeThe dead volume shall be given in cubic millimeters (cubic inches).
31、 For differential pressure transducers, the volume of both cavities should be listed.4.1.2.6 Volume change due to full scale pressureThe change in volume of the sensing element due to application of full scale pressure shall be given in cubic millimeters (cubic inches).4.1.2.7 Materials in contact w
32、ith the measured fluidThe materials in contact with the measured fluid shall be listed.NOTE For differential pressure transducers, materials in both ports must be considered.4.1.2.8 Gage vent (port)In gage pressure transducers where the transduction element is exposed to ambient atmosphere, the allo
33、wable types and concentrations of atmospheric contaminant shall be specified.4.1.2.9 Maximum and minimum temperaturesThe maximum and minimum temperatures of fluids or environments, which can be applied to the transducer and which will not cause permanent calibration shift, shall be listed.NOTE Expos
34、ure time shall be specified, if relevant.4.1.3 Required electrical design characteristicsThe following electrical design characteristics shall be listed. All are applicable at Room Conditions.*4.1.3.1 Excitation*Expressed as “_volts (mA) DC“ or “_ volts (mA) AC rms at _ Hz.“4.1.3.2 Maximum excitatio
35、nExpressed as “_volts (mA) DC“ or “_volts (mA) AC rms at _ Hz.“4.1.3.3 Transduction element resistance*Expressed as “_ _ohms.“4.1.3.4 Electrical connectionsWhether the electrical termination is by means of a connector or a cable, the pin designations or wire color code shall conform to the following
36、 transducer wiring standard.*Defined in ISA-S37.1*Defined in 4.314 ISA-S37.6-1982 (R1995)NOTES1. For differential pressure transducers, the arrow indicates pressure at the measurand port greater than pressure at the reference port.2. The transduction element(s) shall be arranged with increasing “pos
37、itive“ voltage output as caused by increasing resistance between the wiper and low pressure (common) end of winding.4.1.3.5 Insulation resistance*Expressed as “ _ megohms at _ volts DC between all transduction element terminals in parallel and the transducer case at a temperature of _ C and 90 perce
38、nt relative humidity.“4.1.3.6 Breakdown voltage rating*Expressed as “Capable of withstanding volts ac-rms at _ hertz, at a temperature of _ C and 90 percent relative humidity for _ minutes.“4.1.3.7 Load impedance*Expressed as “ _ ohms“ (see 4.2.29).NOTE Although load impedance (the impedance present
39、ed to the output terminals of the transducer by the associated external circuitry) is not a transducer but a system characteristic, it should be specified in order to define loading error. A single, close-tolerance value of load impedance shall be specified for use during all tests where not otherwi
40、se noted.*Defined in ISA-S37.1ISA-S37.6-1982 (R1995) 154.2 Performance characteristicsThe performance characteristics of the potentiometric pressure transducers should be tabulated in the order shown. Unless otherwise specified, they apply at Room Conditions as defined in ISA-S37.1. Characteristics
41、are usually referred to the output and expressed as “% VR“ (i.e., “percent Voltage Ratio“ *).4.2.1 Range*Expressed as “ _ to _ Pa (psi)“ or “+ _ Pa (psid).“NOTE Equivalent pressure units in the SI system are expressed in Pascals.1 psi = 6894.8 Pa10KPa = 1.4504 psi4.2.2 End points*Expressed as “ _ %
42、_ % and _ % _ % VR.“NOTE “%VR“ is “percent *Voltage Ratio.“End Points shall be omitted where adequately defined using Error Band specifications.4.2.3 Full scale output*Expressed as “_ % _ % VR.“NOTE Full scale output shall be omitted where adequately defined using End Points or Error Band specificat
43、ions.4.2.4 Linearity*Expressed as “_ linearity shall be within _ % VR.“NOTE The linearity modifier shall be one of those defined in ISA-S37.1; namely, end point, independent, least squares, terminal, or theoretical slope.4.2.5 Hysteresis*Expressed as “ _ % VR.“Alternately, 4.2.4 and 4.2.5 may be com
44、bined as 4.2.6.4.2.6 Combined hysteresis* and linearity*Expressed as “combined hysteresis and linearity within _ % VR.“NOTE The linearity modifier shall be stated.4.2.7 Friction error*Expressed as “within _% VR.“*Defined in ISA-S37.116 ISA-S37.6-1982 (R1995)4.2.8 Repeatability*Expressed as “within _
45、% VR over a period of _ hours.“Alternately, 4.2.2, 4.2.3, 4.2.4, 4.2.5, 4.2.7, and 4.2.8 may be combined as 4.2.9.4.2.9 Static error band*Expressed as “ _%VR as referred to _ (curve) _.“NOTE The curve shall be stated asa) End Point Line a straight line between end points.b) Best Straight Line a line
46、 midway between the two parallel lines closest together and enclosing all output versus measurand values.c) Least Square Line a straight line for which the sum of the squares of the residuals is minimized.d) Terminal Line a straight line between 0 and 100% of both measurand and output.e) Theoretical
47、 Slope a straight line between the theoretical end points.f) Other curves shall be defined if specified; e.g., mean-output curve.4.2.10 Friction-free error band*Expressed as “ _% VR as referred to _ (curve) _.“NOTE The reference curve shall be specified (see 4.2.9).4.2.11 Resolution* (see also 4.3)E
48、xpressed as “average resolution within _% VR and maximum resolution within _% VR.“4.2.12 Reference-pressure errorExpressed as “change in end points within _% VR for a reference pressure change of _Pa (psi) over a reference pressure range of _ to _Pa (psi).“ Alternately expressed as “operation at ref
49、erence pressures from _Pa (psi) to _Pa (psi) shall not cause output readings which exceed the specified error band.“4.2.13 Frequency response*Expressed as “within _% from zero to _ Hz.“NOTE Frequency response should be referred to response at a frequency within the specified frequency range, preferably zero, and to a specific static pressure. Mounting conditions
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