trans duct ores piezoelectricos y sonicos

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Standard

I S A - S 3 7 . 1 0 - 1 9 8 2 ( R 1 9 9 5 )

Approved September 29, 1995

Specifications and Tests

for Piezoelectric Pressureand Sound-Pressure

Transducers


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Copyright 1995 by ISA. All rights reserved. Printed in the United States of America. No part ofthis publication may be reproduced, stored in a retrieval system, or transmitted in any form or byany means (electronic, mechanical, photocopying, recording, or otherwise), without the priorwritten permission of the publisher.

ISA67 Alexander DriveP.O. Box 12277Research Triangle Park, North Carolina 27709

ISA-S37.10 Specifications and Tests for Piezoelectric Pressure and Sound-Pressure Transducers

ISBN 0-87664-382-9


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ISA-S37.10-1982 (R1995) 3

Preface

This preface, as well as all footnotes and annexes, is included for informational purposes and is

not part of ISA-S37.10.This standard 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 realvalue, this document should not be static but should be subject to periodic review. Toward thisend, the Society welcomes all comments and criticisms and asks that they be addressed to theSecretary, Standards and Practices Board; ISA; 67 Alexander Drive; P.O. Box 12277; ResearchTriangle Park, NC 27709; Telephone: (919) 549-8411; Fax: (919) 549-8288; E-mail:[email protected].

The ISA Standards and Practices Department is aware of the growing need for attention to themetric system of units in general, and the International System of Units (SI) in particular, in thepreparation of instrumentation standards, recommended practices, and technical reports. The

Department is further aware of the benefits to USA users of ISA Standards of incorporatingsuitable references to the SI (and the metric system) in their business and professional dealingswith other countries. Towards this end, this Department will endeavor to introduce SI and

acceptable metric units in all new and revised standards to the greatest extent possible. TheMetric Practice Guide, which has been published by the Institute of Electrical and ElectronicsEngineers as ANSI/IEEE Std. 268-1992, and future revisions, will be the reference guide fordefinitions, symbols, abbreviations,and conversion factors.

It is the policy of ISA to encourage and welcome the participation of all concerned individuals andinterests in the development of ISA standards, recommended practices, and technical reports.

Participation in the ISA standards-making process by an individual in no way constitutesendorsement by the employer of that individual, of ISA, or of any of the standards which ISA

develops.This Standard was originally prepared by the SP37.10 Committee which operated under theguidance of SP37.

The following individuals served on the original SP37.10 Subcommittee:

NAME COMPANY

N. Keast, Chairman Bolt, Beranek and Newman, Incorporated

G. T. Cozad McDonnell Douglas Corporation

L. Horn National Bureau of Standards

R. W. Lally PCB PiezotronicsJ. Rhodes Endevco Corporation


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4 ISA-S37.10-1982 (R1995)

The following individuals served on ISA Committee SP37, who reaffirmed ISA-S37.10 in 1995:

NAME COMPANY

E. Icayan, Chairman Westinghouse Hanford Co.

J. Weiss Electric Power Research Inst.

P. Bliss, Deceased Consultant

M. Brigham The Supply SystemD. Hayes LA Dept. Water & Power

M. Kopp Validyne Corp.

C. Landis Weed Fiber Optics

J. Miller Rosemount Inc.

A. Mobley 3M Co.

J. Mock Consultant

D. Norton McDermott Energy Svces Inc.

H. Norton Consultant

M. Tavares Boeing Defense & Space Group

R. Whittier EndevcoJ. Wilson Consultant

This standard was reaffirmed by the ISA Standards and Practices Board on September 29, 1995.

NAME COMPANY

M. Widmeyer, Vice President Washington Public Power Supply System

H. Baumann H. D. Baumann & Associates, Inc.

D. Bishop Chevron USA Production Company

P. Brett Honeywell, Inc.

W. Calder III Foxboro CompanyH. Dammeyer Phoenix Industries, Inc.

R. Dieck Pratt & Whitney

H. Hopkins Utility Products of Arizona

A. Iverson Lyondell Petrochemical Company

K. Lindner Endress + Hauser GmbH + Company

T. McAvinew Metro Wastewater Reclamation District

A. McCauley, Jr. Chagrin Valley Controls, Inc.

G. McFarland Honeywell Industrial Automation and Controls

J. Mock Consultant

E. Montgomery Fluor Daniel, Inc.D. Rapley Rapley Engineering Services

R. Reimer Allen-Bradley Company

R. Webb Pacific Gas & Electric Company

W. Weidman Consultant

J. Weiss Electric Power Research Institute


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ISA-S37.10-1982 (R1995) 5

Contents

1 Scope ................................................................................................................................. 7

2 Purpose.............................................................................................................................. 7

3 Drawing Symbol ............................................................................................................... 8

4 Characteristics ................................................................................................................. 9

4.1 Design characteristics............................................................................................ 10

4.2 Performance characteristics .................................................................................. 13

4.3 Additional terminology ........................................................................................... 17

5 Individual acceptance tests and calibrations .............................................................. 18

5.1 Visual inspection .................................................................................................... 18

5.2 Voltage or charge sensitivity, range, and linearity ................................................. 185.3 Proof pressure (pressure transducers) (4.2.2.6).................................................... 20

5.4 Frequency response, resonant frequency andresonant frequency amplification ........................................................................... 20

5.5 Transducer capacitance ........................................................................................ 22

5.6 Shunting resistance ............................................................................................... 22

5.7 Insulation resistance (for transducers isolated from case ground) ........................ 22

5.8 Transducer cable (non-integral)............................................................................. 22

6 Qualification tests .......................................................................................................... 23

6.1 Transducer seal test (sealed transducer only). ..................................................... 23

6.2 Cable noise test. ................................................................................................... 23

6.3 Ambient-pressure sensitivity shift (4.2.1.12). ........................................................ 24

6.4 Vibration error (4.2.1.10) . ..................................................................................... 24

6.5 Linear-acceleration effects (4.2.1.11.f) ................................................................. 24

6.6 Thermal sensitivity shift at maximum and minimumoperating temperature (4.2.1.7). ........................................................................... 25

6.7 Temperature gradient error (4.2.1.8). ................................................................... 25

6.8 Sensitivity stability (4.2.1.11). ............................................................................... 26

6.9 Burst Pressure (pressure transducers) (4.2.1.6) ................................................... 26

7 Sample data sheets ........................................................................................................ 26

Annex A References ..................................................................................................... 33

Figures

1 Sample data sheet No. 1............................................................................................... 27




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ISA-S37.10-1982 (R1995) 7

1 Scope

1.1 This standard covers piezoelectric (including ferro-electric) pressure transducers and piezo-electric sound pressure transducers. Pressure and sound-pressure types could be the same

instrument differing only in the method of calibration and manner of specifying performance. Withthe exception of certain impedance and charge measurements, this standard is also applicable to

piezoelectric transducers with built-in amplifiers.

Sound pressure transducers sense and measure the pressure oscillations within an elastic fluidmedium experiencing stress-strain waves. When installed near the sound source or in the wall ofa test object, the transducer behavior relates to its pressure response. When installed in a soundfield, considerable interaction occurs at higher frequencies during the measuring transaction,changing the quantity being measured and relating transducer behavior to its free-field or diffuse-

field response. Both aspects of transducer behavior are covered in this standard.

1.2 Included among the specific types of piezoelectric pressure transducers to which this standard

is applicable are the following:

a) Piezoelectric pressure transducers for transient pressure measurements

b) Piezoelectric pressure transducers that, in conjunction with associated electronicequipment, have quasi-dc response to gage pressures

c) Piezoelectric transducers for sound pressure levels in excess of 100 dB overall re20 Pa associated with fluid-borne noise

1.3 Terminology used in this document is defined in ISA-S37.1, except that additional definitionsparticularly applicable to piezoelectric pressure and piezoelectric sound-pressure transducers are

defined in 4.3 of this document.

2 Purpose

This Standard establishes the following for piezoelectric pressure and piezoelectric sound-pressure transducers.

2.1 Uniform minimum general specifications for describing design and performance characteristics

2.2 Selected uniform acceptance and qualification test methods, including calibration techniques

2.3 Uniform procedures for the presentation of transducer test data

2.4 A drawing symbol for use on measurement system electrical schematics (See Note in

Section 3.)


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8 ISA-S37.10-1982 (R1995)

3 Drawing Symbol

The drawing symbol for a transducer is a square with an added equilateral triangle, the base ofwhich is one side of the square. The triangle symbolizes the sensing element.

The piezoelectric element is symbolized by a small rectangle encompassing two diagonallycrossing lines. Surrounding this rectangle is the electrical symbol for a capacitor. Lines from thesymbolic capacitor to the right side of the large square represent the electrical leads.

NOTE This symbol is not ANSI-approved at this time. It has been submitted to theANSI Y32 Committee on Graphic Symbols for their consideration and approval.

Indicates caseconnection,if any


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ISA-S37.10-1982 (R1995) 9

4 Characteristics

Summary

Individual Acceptance

Tests Qualification

TestsBasic Supplemental go/no-go measured

Cable Characteristics

(state whether integral or nonintegral)

Type 4.1.1 5.1Length 4.1.1 5.8.1Connector(s) used 4.1.1 5.1Temperature range 4.1.1

Capacitance at Room Temperature 4.1.3 5.8.1Noise Characteristics 4.1.4 6.2Case Connector Sealing (if applicable) 4.1.1 6.1Dimensions, configurations, and markings 4.1.1 5.1Connector Type 4.1.1 5.1Exposed Materials 4.1.1Transduction Element Material

Type 4.1.1Sensing Mode 4.1.1

Mounting Method 4.1.1 5.1

Transducer Temperature Range (excluding cable ifnonintegral)

Operating 4.2.1.9 6.6Storage 4.1.4

Dead Volume 4.1.2Equivalent Volume 4.1.2Diaphragm Material and Thickness 4.1.2Vibration Isolation or Cancellation Descriptions

Mechanical 4.1.2 6.4Electrical 4.1.4 6.4

Capacitance

Room Temperature 4.1.3 5.5Over Temperature Range 4.1.4 6.6

Grounding 4.1.3 5.7Insulation Resistance (if applicable)

Room Temperature 4.1.3 5.5

Over Temperature Range 4.1.4Shunting Resistance

Room Temperature 4.1.3 5.5Over Temperature Range 4.1.4 6.6

Range 4.2.1.1 5.2Sensitivity

At Room Temperature (nominal+tolerance)

Over Temperature Range 4.2.1.7 6.6Over Ambient Pressure Range (sound-pressure

transducers only) 4.2.1.13 6.3Stability 6.8

Frequency Response

Pressure Transducers 4.2.1.3 5.4.1Sound-Pressure Transducers 4.2.1.3 5.4.2

Linearity 4.2.1.4 5.2Pressure-Excited Resonance

At lowest resonant frequency 4.2.1.14 5.4.1At additional frequencies 4.2.2.1 5.4.1

Proof Pressure Pressure Transducers 4.2.1.5 5.3Burst Pressure Rating Pressure Transducers 4.2.1.6 6.9Spurious Output from Temperature Gradient 4.2.1.8 6.7Vibration Error 4.2.1.10 6.4Directivity 4.2.1.15 5.4.2Susceptibility to Environments

Mechanical Shock 4.2.1.11Humidity 4.2.1.11Salt Spray 4.2.1.11Nuclear Radiation 4.2.1.11Electromagnetic Interference 4.2.1.11 6.8Steady-state Acceleration 4.2.1.11 6.5


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10 ISA-S37.10-1982 (R1995)

4.1 Design characteristics

4.1.1 Basic mechanical design characteristics

The following mechanical design characteristics are required to be l isted:

a) Cable, non-integral

If a non-integral cable is supplied with the transducer, the type, length, connector types,and maximum operating temperature of this cable shall be specified. (Requirements forthe specification of electrical cable characteristics are given in 4.1.3).

b) Case sealing

If case sealing is employed, the mechanism and materials for sealing shall be described.The same requirement applies to the electrical connector. The resistance of the sealingmaterials to common and corrosive fluids shall be stated.

c) Connection, pressure

The pressure connection shall be indicated on the outline drawing [see (e) Dimensions].

For threaded cases of fittings, indicate the nominal size, thread pitch, thread series, andthread class. For a flush-mounted transducer, indicate whether flange mounting,cemented installation, or other specified means is employed.

d) Connector, electrical

The connector on the transducer shall be described. If the transducer is supplied withan integral cable, the connector at the end of the cable shall be described. The mating

connector for the above connector shall also be described or designated.

e) Dimensions

An outline drawing of the transducer shall show its complete configuration with

dimensions given in millimeters (or inches).

f) Identification

The following characteristics shall be permanently inscribed on the outside of the

transducer case or (for very small transducers) supplied with the transducer:

1) Nomenclature of transducer (According to ISA-S37.1, Section 3)

2) Name or trademark of manufacturer. Model (Part) Number, and Serial Number

3) Range (if applicable)

g) Materials, housing

The case materials exposed to the environment shall be identified.

h) Material, transduction element

The type of piezoelectric material employed as the transduction element shall beidentified. (A proprietary name is acceptable.) The sensing mode of this element shallalso be specified.


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ISA-S37.10-1982 (R1995) 11

i) Fluid limitations

If specific corrosive fluids are associated with a particular transducer application, thecompatibility of the transducer and its accessories with such specified fluids shall bestated.

j) Mounting and mounting dimensions

Unless the pressure connection serves as the transducer mounting, the outline drawingshall indicate the method of mounting with dimensions in millimeters or inches.

k) Mounting force or torque

Mounting force or torque shall be specified. When pressure connection is not integralwith mount, pressure-connection torque shall also be specified.

l) Weight

The weight of the transducer shall be specified in grams (or ounces). If the transducerincludes an integral cable, its weight also shall be stated.

4.1.2 Supplemental mechanical design characteristics

Listing the following mechanical design characteristics is optional.

a) Dead volume

For non-flush-mounted transducers, the dead volume may be given in cubic millimeters(or cubic inches). For piezoelectric sound-pressure transducers, theEquivalent Volumedue to the compliance of the diaphragm may be specified to assist in transducer

calibrations.

b) Identification

The following supplemental information may be inscribed on the transducer case:

1) Sensitivity

2) Customer Specification, Part Number, or both

3) Type of Electrical Connector

4) Maximum Operating Pressure

5) Maximum Operating Temperature

c) Material, pressure sensing

The diaphragm material and thickness may be specified, if a diaphragm is employed.

d) Vibration isolation

If the transduction element is mechanically isolated in some way from the transducermounting points (to reduce vibration sensitivity) this may be described.


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12 ISA-S37.10-1982 (R1995)

4.1.3 Basic electrical design characteristics

The following electrical design characteristics are required to be listed. They are applicable at"room conditions" according to the definition given in ISA-S37.1.

a) Capacitance

The capacitance of the transducer and that of any non-integral cable shall be stated

separately. Capacitances shall be expressed as "______ picofarads."b) Grounding

It shall be stated whether or not one of the transducer signal leads is internally connectedto case ground electrically.

c) Resistance, shunting

Expressed as "not less than______megohms at ______volts dc" as applied for twominutes between the two output terminals, unless a different time is specified.

d) Resistance, insulation

Insulation resistance shall be expressed as "not less than______megohmsat______volts dc" as applied for two minutes between both output terminals connectedin parallel and the transducer case at the mounting point. Note that this requirement isnot applicable for those transducers that are internally grounded.

e) Temperature range (storage)

All restrictions on the temperature at which the transducer can be safely stored shall bespecified.

f) Load impedance

The impedance presented by the immediately associated measuring system (cable ifnot integral, amplifier, etc.) to the transducer's output terminals shall be specified eitheras a minimum value, a range of values, or a nominal value with tolerances. All specified

performance characteristics are intended to be applicable under this specified load-impedance condition.

4.1.4 Supplemental electrical design characteristics

Listing the following electrical design characteristics is optional:

a) Capacitance vs. temperature

This may be given as a graph of transducer temperature. A corresponding curve ofcable capacitance vs. cable temperature may also be provided.

b) Cable noise

The noise produced by the transducer cable when mechanically excited in somespecified way may be stated (see 6.2).

c) Insulation resistance vs. temperature

This may be given as a curve of the transducer insulation resistance vs. temperature.


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ISA-S37.10-1982 (R1995) 13

d) Shunting resistance vs. temperature

This may be given as a curve of the shunting resistance of the transducer vs. transducertemperature.

e) Vibration cancellation (electrical)

Any built-in electrical method for reducing the vibration sensitivity of the transducer may

be specified.

f) Polarity

The positive-going output terminal for an applied increase in pressure may be specified.

4.2 Performance characteristics

The pertinent performance characteristics of piezoelectric pressure and piezoelectric sound-

pressure transducers shall be tabulated in the order shown. Unless otherwise specified, theyapply at "room conditions" as defined in ISA-S37.1; i.e., Temperature: 25 10C (77 18F);Relative Humidity: not to exceed 90 percent; Barometric Pressure: 730 70 millimeters Hg(29 3 in. Hg).

Terminology used here is defined either in ISA-S37.1 or in 4.3 of this document. An asteriskappears beside the paragraph number of those terms defined in S37.1.

It is important that all transducer performance characteristics be listed independent of thecharacteristics of any amplifier and/or non-integral cables supplied with the transducer.(Performance characteristics may also be supplied including the effects of amplifiers and cables,if so identified as supplemental information.) In those cases where such characteristics cannotbe stated independent of amplifier properties, the pertinent amplifier and cable type, partnumber, and properties shall also be specified.

All performance characteristics are applicable under the conditions specified for Load

Impedance. Note that this practice is used in lieu of specifying "open-circuit" outputcharacteristics (an earlier practice, which did not permit verification of such characteristics sinceall ancillary equipment has a finite value of input impedance).

NOTE In the following, separate statements are given for pressure transducers and forpiezoelectric sound-pressure transducers in those cases where current terminologies differfor the two applications.

4.2.1 Required performance characteristics

4.2.1.1 Range*

a) Pressure transducers. The range, usually expressed as " ____Pa (psi)" or"0 to ____Pa (psi.)"

b) Piezoelectric Sound-Pressure Transducers. The range is usually expressed as

"____dB sound pressure level (SPL) to ____dB SPL re 20 Pa."

*Defined in ISA-S37.1


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4.2.1.2 Sensitivity, charge or voltage*

a) Pressure Transducers. The voltage sensitivity is expressed as "____mV perPa (psi) ____%," or as "_____ ____mV per Pa (psi)." Equivalently, charge sensitivitymay be expressed as "_____ picocoulombs per Pa (psi) _____%," or as "_____

_____ picocoulombs per Pa (psi)."

In any case, it is assumed that the pressure and electrical parameters are both reported

as peak, average, or rms values unless stated otherwise.b) Piezoelectric sound-pressure transducers. The voltage sensitivity level is expressed

in dB as 20 times the logarithm to the base 10 of the ratio of the sensitivity to the referencesensitivity. That is, sensitivity level S, re 1V/Pa, is

S = LV Lp = 20 log10 V/p

where Lv is the output voltage, re 1V, produced by applied sound pressure level Lp,re 20Pa. Appropriate tolerances should be shown for a specified nominal value.Alternatively, the charge sensitivity level may be expressed as "_____ _____dB

re 1 picocoulomb per Pascal."

4.2.1.3 Frequency response*

a) Pressure transducers. This is expressed as "within _____% of the sensitivity at____ Hz from _____ to ____ Hz." The method for determining this frequency responseshould be described.

b) Piezoelectric sound-pressure transducers. Frequency response shall be specified

as "____ type frequency response) within 3 dB (or, alternatively, within 1 dB) from____ Hz to ____ Hz." The quantity entered into the first blank shall be one of the following(as defined in 4.3): calculated frequency response*, pressure response,free-field grazing incidence response, free-field normal incidence response, or free-fieldrandom incidence response.

Frequency response shall be referred to a frequency within the specified frequency

range of the transducer and to a specific fluid. The methods of mounting the trans-ducer and applying the test fluid should both be specified.

4.2.1.4 Linearity*

a) Pressure transducers. Linearity is normally expressed as "_____ linearity within _____% of full (or a specified partial) scale output." The type of linearity to be enteredin the first blank above shall be one of the straight line types defined in ISA-S37.1;namely: end point, independent, least squares, terminal, or theoretical slope.

b) Piezoelectric sound-pressure transducers. Linearity is generally expressed as"____ linearity within _____dB." The type of linearity specified in the first blank shallbe one of the straight one types defined in ISA-S37.1.

4.2.1.5 Proof pressure*

a) Pressure transducers. Proof Pressure shall be expressed as (application of)

"____Pa (psi) for ____ minutes" (will not cause changes in transducer performance thatexceed its specified error limits).



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ISA-S37.10-1982 (R1995) 15

4.2.1.6 Burst pressure rating*

a) Pressure transducers. Burst Pressure Rating is stated as "____Pa (psi) applied____times for a period of ____ minutes each" (will not result in mechanical failure of thetransducer housing).

4.2.1.7 Thermal sensitivity shift*

a) Pressure transducers. Thermal Sensitivity Shift is expressed in terms of a maximumchange from the (actual) room-temperature sensitivity level over the specified operatingtemperature range* as "____ % maximum, from ____C(F) to ____C(F)."

b) Piezoelectric sound-pressure transducers. Thermal Sensitivity Shift is expressedas " _____dB" (sensitivity level change over the specified operating temperaturerange*) "from _____C(F) to ____C(F)."

4.2.1.8 Temperature gradient error*

Expressed as "less than _____ mV output when subjected to a step-function temperaturechange from _____C(F) to _____C(F), applied to (specify particular part) of the transducer"(at constant ambient pressure).

State whether Procedure I or II of 6.7 is to be used to verify this characteristic.

NOTE Alternatively, the temperature-gradient error may be expressed as equivalentPa (psi) input (for pressure transducers), or in picocoulombs output for transducers to beused with charge amplifiers, or in dB SPL.

4.2.1.9 Maximum and minimum ambient temperature*

Expressed as (the transducer can be operated indefinitely at any temperature within the rangefrom) "_____C(F) to _____C(F)" (without incurring a permanent calibration shift).

4.2.1.10 Vibration error*

a) Pressure transducers. Vibration error limits are expressed as "less than ____ mV"(or alternately, picocoulombs) "rms output due to ____ g rms acceleration along anyaxis over a frequency range from ____ Hz to ____ Hz." The errors shall be listed foreach of three mutually perpendicular axes, or for that axis expected to have the largestvibration error. State whether a swept sinusoidal or broad-band random vibration input

is to be employed. In the latter case it is preferable to show a graphical representationof the vibration program.

b) Piezoelectric sound-pressure transducers. Vibration error limits may be expressedas "less than ____ dB equivalent SPL output due to ____ g rms acceleration along any

axis over a frequency range from ____ Hz to Hz." State whether a swept sinusoidal orbroad-band random vibration input is to be employed.

NOTE Alternatively, the equivalent SPL output may be expressed relative to peak

acceleration, provided that this is made clear and that the type of vibration waveform isspecified.



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4.2.1.11 Other environmental conditions*

Other pertinent operating* or non-operating* environmental conditions that shall not affect thetransducer performance beyond the specified limits shall be listed; examples are as follows:

a) Mechanical Shock

b) Humidity

c) Salt Spray

d) Nuclear Radiation

e) Electromagnetic Interference

f) Acceleration (steady)

g) Ambient Pressure

The test conditions for determining such properties shall be identified.

4.2.1.12 Sensitivity stability

a) Pressure transducers. Sensitivity stability shall be stated as, "The sensitivity shall notvary more than _____ % of its room-temperature value when subjected to ____temperature cycles between ____C(F) and ____ C(F) and to ____ pressure cyclesup to ____ Pa (psi)."

b) Piezoelectric sound-pressure transducers. Sensitivity Stability shall be stated as,"The sensitivity level shall not vary more than ____dB when subjected to ____temperature cycles between ____C(F) and____C(F) and to sound pressure levelsup to ____dB re 20Pa at ____ Hz."

4.2.1.13 Ambient-pressure sensitivity shift*

a) Piezoelectric sound-pressure transducers. The allowable sensitivity shift due to

variations in ambient pressure shall be expressed as, "The microphone sensitivity levelwill not vary more than ____ dB when operated at any ambient pressure within therange from ____ Pa (psia) to ____ Pa (psia)."

4.2.1.14 Resonant frequency amplification factor

a) Pressure transducers. Resonant frequency amplification factor at the lowest resonantfrequency shall be expressed as "the amplification factor at resonant frequency____ Hz shall not exceed ____."

b) Piezoelectric sound-pressure transducers. Resonant frequency amplification factor

at the lowest resonant frequency shall be expressed as "the amplification factor resonantfrequency ____ Hz shall not exceed ____ dB."

4.2.1.15 Directivity*

a) Piezoelectric sound-pressure transducers. The Directivity shall be specified as anallowable envelope for a specified directivity characteristic (directional response pattern,see 4.3).



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ISA-S37.10-1982 (R1995) 17

4.2.2 Optional performance characteristics

4.2.2.1 Resonant frequency characteristics of sensing elements

Amplification (damping) at additional frequencies shall be expressed as in 4.2.1.14.

4.3 Additional terminology

4.3.1 decibel (dB): (see ANSI-S1.1 reference) (see also Sound Pressure Level). A unit of level,where

P1 = a power, or, quantity directly proportional to power.

Pref = a reference power, or, a corresponding reference quantity proportional to power.

4.3.2 diffuse-field response: A frequency response of a piezoelectric sound-pressure transducerwith the sound incident from random directions.

4.3.3 directivity characteristic: (Directional Response Pattern) (see Beranek reference). A plotof the sensitivity level of piezoelectric sound-pressure transducer vs. the angle of sound incidenceon its sensing element relative to the sensitivity level in a specified direction, and at a specifiedfrequency.

4.3.4 equivalent volume: (see ANSI-S1.12 reference). The volume of a gas enclosed in a rigidcavity which would give the same acoustical input impedance as that of the piezoelectrical sound-

pressure transducer.

4.3.5 free-field frequency response: (see ANSI-B88.1 reference). The free-field frequency re-

sponse of a piezoelectric sound pressure transducer is the ratio, as a function of frequency, of thetransducer's output in a sound field to the free-field sound pressure existing at the transducer

location in the absence of the transducer.

4.3.6 free field (sound): (see ANSI-S1.1 reference). A free sound field is one existing in a homo-geneous, isotropic medium free of any acoustically-reflecting boundaries.

4.3.7 free-field grazing incidence response: A free-field frequency response of a piezoelectricsound-pressure transducer with the sound incident parallel to a specified sensing surface of themicrophone.

4.3.8 level: (see ANSI-S1.1 reference). A measure of the logarithm of the ratio of some quantityto a reference quantity of the same kind. The reference quantity must be identified.

4.3.9 pressure (frequency) response: The pressure frequency response (pressure response)of a piezoelectric sound-pressure transducer is the ratio, as a function of frequency, of the trans-ducer output to a sound pressure input which is equal in phase and amplitude over the entiresensing surface of the transducer.

The pressure frequency response is generally equal to the free-field frequency response atwavelengths long compared to the maximum dimension of the piezoelectric sound-pressuretransducer.

Level in dB 10 10

P1

Pref

----------log=


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18 ISA-S37.10-1982 (R1995)

4.3.10 resonant frequency amplification factor: The ratio of the maximum sensitivity of a

transducer at its lowest resonant frequency to its nominal sensitivity.

4.3.11 sensitivity stability: A measure of the irreversible change in transducer sensitivity levelafter exposure to temperature and/or pressure extremes, or with time.

4.3.12 shunting resistance: The electrical resistance observed between the two terminals of apiezoelectric transducer or its integral cable.

4.3.13 sound pressure level (SPL): (see ANSI-S1.1 reference). Defined in decibels as

Where p2 is mean square sound pressure and pref is reference pressure, which shall be stated as

20 Pa.

NOTE Sound level (see ANSI-S1.1 reference) is a weighted sound pressure level readingobtained by use of metering characteristics and weightings A, B, or C specified in ANSI

Standard S1.4-1971. This is not to be confused with sound pressure level.

5 Individual acceptance tests and calibrations

Tests are listed in the order in which they are to be performed.

Results obtained during these calibrations and test procedures shall be recorded on data sheetssimilar to the sample data sheet inSection 7of this guide. These procedures shall be performed

under "room conditions," as defined in ISA-S37.1, unless otherwise indicated and underspecified load impedance conditions.

References to the pertinent paragraphs in 4.2 are given in parentheses.

5.1 Visual inspection

Conduct a complete visual examination for conformance to stated configuration and markings.Determine dimensions, thread sizes, and thread classes utilizing standard inspection

instruments. Check mating of accessory cable (if any) by attaching and removing the cable.

5.2 Voltage or charge sensitivity, range, and linearity

For most applications, the sensitivity (level) of the transducer may be determined by comparison

with a secondary standard transducer. The secondary standard transducer used shall have acalibration traceable to a calibration performed at the National Bureau of Standards (or at anothersuitable facility using a well-documented absolute calibration procedure) with a normal calibrationperiod of one year. The transducer used as a standard shall be reserved for this purpose only; it

shall not be exposed to large values of shock, vibration or temperature extremes; and itscalibration shall be checked periodically.

In general, although the calibration of a piezoelectric pressure transducer may require the use ofa connecting cable and amplifier, the effective voltage sensitivity (or equivalent charge sensitivity)

SPL (dB) 10 log10p2

pre f

2( )---------------- 20 log10

p rms( )

pre f

rms( )

-------------------= =


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ISA-S37.10-1982 (R1995) 19

of the transducer shall be determined. Statement of the calibration of a transducer, cable, and

amplifier solely as a system shall be avoided.

5.2.1 Voltage and charge sensitivity, range, and linearity of transducers withquasi-dc response

A piezoelectric pressure transducer which has, in conjunction with an associated amplifier,essentially dc response may be calibrated against a standardized source of constant pressure.

Typical example of such sources are the mercury manometer, air piston gauge, precision dialgauge, oil piston gauge, etc. (see ISA-S37.3). The error of the pressure source shall be one-fifth

(or less) the permissible error tolerance of the transducer performance characteristics underevaluation. The range of the instruments supplying or monitoring the calibration pressure shallbe selected to provide the necessary accuracy to 125 percent of the full-scale range of thetransducer.

The source of calibration pressure may be either continuously variable over the range of theinstrument or may be provided in discrete steps, as long as the pressure is returned to zero after

each step.

The transducers shall be connected to the pressure source and secured with recommendedforce or torque. The necessary cable, amplifier, and readout instruments shall also be connected

to the transducer and turned on. Adequate warmup time shall be allowed for the test equipmentbefore tests are conducted. The pressure source, connecting tubing, and transducer systemsshall have passed a prior test for leaks that might cause calibration errors.

Two or more complete calibration cycles shall be run consecutively. At least five data points shallbe obtained in both ascending and descending directions of pressure application. Amplifiercharacteristics shall be monitored as required.

The voltage sensitivity of the transducer is determined by the ratio (at full scale) of the transduceroutput in millivolts (suitably corrected for the gain of any amplifier employed, and for the effect ofany cables employed) divided by the full scale static pressure applied. Charge sensitivity level

can be determined by using a charge amplifier of known characteristics, or by multiplying thevoltage sensitivity level in volts per Pa (psi) by the total capacitance of the system (i.e., that of the

transducer and its associated cable, and the effective input capacitance of the voltage amplifier)in picofarads, yielding charge sensitivity in picocoulombs Pa (psi).

From the data obtained in these tests, the following characteristics shall be determined:

a) Sensitivity 4.2.1.2

b) Range 4.2.1.1

c) Linearity 4.2.1.4

5.2.2 Voltage or charge sensitivity, range, and linearity of pressure transducers not capableof quasi-dc response

The sensitivity (level) of a transducer not capable of quasi-dc response may be determined bycomparison with a secondary standard transducer, or by the reciprocity technique (see Beranekreference). The latter method is limited to use with piezoelectric sound-pressure transducers andlow-range pressure transducers. The former method is described here.

It is preferable that the secondary-standard transducer be capable of dc response, so that it maybe calibrated in turn in the manner described in 5.2.1. In order to excite the transducers, a sourceof transient or alternating pressure is necessary. Among the former are the shock tube, quick-opening valve devices, burst-diaphragm devices, etc. (see Schweppe, et al. reference). Amongthe latter are loudspeakers, various siren-type devices, and hydraulically driven actuators (see


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20 ISA-S37.10-1982 (R1995)

Schweppe, et al. reference). In general, it is preferable that the transient or alternating pressure

applied to the transducer be comparable to the rated full-scale pressure of the transducer undertest. Frequently, however, a suitable actuating device satisfying this requirement is not available,and pressures well below full-scale must be used for calibration purposes.

The sensitivity of the transducer is computed as the ratio of the maximum instantaneous outputvoltage of the transducer (after suitable corrections for associated cables and amplifiers) in

millivolts to the maximum instantaneous pressure applied to produce this output. Equivalently, if

the pressure excitation is sinusoidal, the ratio of the rms output voltage, in millivolts, to the rmspressure applied may be determined.

Charge sensitivity can be measured with a charge calibrator (Q-step calibrator), or a chargeamplifier of known characteristics, or calculated by multiplying the voltage sensitivity in volts perPa (psi) by the total capacitance of the system in picofarads, yielding charge sensitivity in

picocoulombs per psi.

By repeating the above tests at various measured amplitudes, it is possible to determine

a) Sensitivity 4.2.1.2

b) Range 4.2.1.1(if within the capability of the pressure source)

c) Linearity 4.2.1.4

5.2.2.1 Voltage sensitivity level of piezoelectric sound-pressure transducers (4.2.1.2)

The voltage sensitivity level of microphones is expressed in dB re 1 volt per Pa. This can be

computed from the voltage sensitivity measured as specified in 5.2.1 or 5.2.2 by employing thefollowing equation:

5.3 Proof pressure (pressure transducers) (4.2.2.6)

After application of the specified proof pressure, a specified number of times, at least one

complete calibration cycle shall be performed using the procedures of 5.2.1 or 5.2.2, whichever isapplicable, to establish that the performance characteristics of the transducer are still withinspecifications.

5.4 Frequency response, resonant frequency and resonant frequency amplification

5.4.1 High-range transducers

The dynamic response characteristics of pressure transducers may be established either withtransient-excitation devices or with sinusoidal pressure generators.

5.4.1.1 Transient excitation method

Transient-excitation devices generally produce step functions of pressure. A positive step-function of pressure may be generated in gases with a shock-tube or a quick opening valve. Ahydraulic quick-opening valve is used to generate a positive pressure step function in a liquid

medium. A burst-diaphragm generator is used to produce a negative pressure step in a gasmedium. In all cases, the rise time of the generated step function shall be sufficiently short toshock-excite at least the lowest few resonances of the transducer under test.

Sensitivity Level 20 log10output in volts

input in Pa-------------------------------------=


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ISA-S37.10-1982 (R1995) 21

Since any tubing used to mechanically connect the transducer to the test set-up will affect the

dynamic characteristics, it is recommended either that the shortest possible tubing be installed,or that any tubing used shall duplicate as closely as possible the actual installation.

By applying step functions of pressure at room conditions within the full scale range of thetransducer, and analyzing the electronic or electro-optical recording of the transducer output, thefollowing can be determined:

Frequency Response (amplitude and phase) 4.2.1.3Resonant Frequency 4.2.2.1

NOTE These may be a function both of the polarity of the pressure step and of the type

of test fluid.

5.4.1.2 Sinusoidal excitation method

Generators are available to produce sinusoidal pressure waveforms in either liquids or gases.

These sinusoidal generators operate either on the "piston-phone" principle (which is in commonuse for the absolute calibration of microphones), by modulating a fluid flow through an orifice orby vibrating or rotating a column of liquid in a vertical plane. (See ANSI-S1.1 reference.) By

applying a sinusoidal pressure waveform of varying frequency at a specified static pressure,frequency response (4.2.1.3) can be observed directly by comparison with a suitable referencetransducer.

The following can be established from the frequency response:

a) Resonant Frequencies and their Amplification Factors

b) Damping Ratios

c) Ringing Period

d) Discharge Time Constant

e) Overshoot

5.4.2 Low-range pressure transducers and piezoelectric sound-pressure transducers

For these transducers it is generally possible to measure frequency response directly. A numberof methods exist for this purpose. In general, these methods provide either a pressure responseor a free-field response as defined in 4.3. (The pressure response is the same as the free-field

response for frequencies whose wave lengths in the measure medium are large compared to thedimensions of the transducer. At higher frequencies, the pressure response differs from the free-field response because of diffraction of the sound field by the transducer and its associatedmounting hardware.)

Pressure responses can be obtained with pistonphones, calibration couplers, or electrostatic

actuators. Free-field responses must be measured in an anechoic space and must be measuredin the fluid medium in which the transducer will be employed (see ANSI-1.10, ANSI-B88.1,ANSI-S1.12, ANSI-1.20, and Beranek reference).

In general, because the free-field frequency response of a transducer is affected by its geometry,this response depends upon the direction of propagation of sound waves with respect to thetransducer. Therefore, it is essential that the direction of sound incidence upon the transducer bespecified. Typically, free-field frequency response determinations are made for normal sound

incidence, grazing sound incidence and/or random sound incidence.


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22 ISA-S37.10-1982 (R1995)

To establish directivity, a set of directivity characteristics can be reported that illustrate the

sensitivity of the microphone for sound incident from all possible directions. This is normallydone only on a qualification basis.

From such a test, it is possible to determine, for a low range pressure transducer

a) frequency response 4.2.1.3

b) directivity 4.2.1.15

In some cases, the mechanical resonant frequencies (4.2.2.1) and resonant-frequencyamplifications (4.2.1.5) also can be observed.

5.5 Transducer capacitance

Measure the capacitance of the transducer and any integral cable by means of a capacitancebridge at 1000 Hz; measure the capacitance of the transducer cable at 1000 Hz.

NOTE When very high frequency (fast-response) pressure measurements are to be

made, with the transducer, capacitance measurements at 100,000 Hz should be performedadditionally.

5.6 Shunting resistance

Measure the resistance between the two electrical leads of the transducer with an electrometertype megohmmeter or similar acceptable device, using a potential of 50 volts unless otherwisespecified.

5.7 Insulation resistance (for transducers isolated from case ground)

Measure the insulation resistance between all terminals or leads connected in parallel, and thecase of the transducer, with a megohmmeter or similar acceptable device using a potential of

50 volts applied for two minutes unless otherwise specified.

5.8 Transducer cable (non-integral)5.8.1 Length and capacitance

Measure the length of any non-integral cables supplied with the transducer. It is acceptable ifwithin 6 mm ( 1/4 inch) or 2 % of specified length, whichever is larger, unless otherwisespecified. Measure the capacitance of the non-integral cable with a capacitance bridge at1000 Hz and record. The cable tests shall be done at room temperature as specified inISA-S37.1.

NOTE When very high frequency (fast response) pressure measurements are to bemade with the transducer, capacitance measurements at 100,000 Hz should be performedadditionally.


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ISA-S37.10-1982 (R1995) 23

6 Qualification tests

These tests are performed on representative transducers in addition to the individual acceptancetests and calibrations. One transducer shall be subjected to all applicable portions of the

qualification test unless otherwise specified.

6.1 Transducer seal test (sealed transducer only)

Use a light mineral oil (or equivalent) with a viscosity between 175 and 190 centistokes in a

transparent container such as a Pyrexbeaker. Heat the oil to approximately 125 C or to themaximum temperature specified for the transducer. Remove detachable cables and connectorsfrom the transducer. Immerse the transducer beneath the surface of the heated oil. Any streamof air bubbles released from within the transducer indicates leakage and constitutes failure. Drythe transducer without application of heat (compatible solvents may be used).

6.2 Cable noise test

The mechanically-induced (triboelectric) output noise of a standard length of cable that issupplied with the transducer shall be specified as "less than______ mV (peak-to-peak)" whentested as described in this paragraph (adapted from Perls reference).

The instrumentation shall include a standard shielded capacitor (1000 picofarads) connectedacross the cable; a weight equal to the weight of 12 meters (40 ft) of the cable under test in twohalf-cylindrical shapes that are clamped or taped to the outer jacket of the cable; a pre-amplifieror cathode follower having a specified frequency response and input impedance; and an

oscilloscope or oscillograph with the capability of providing a full-scale deflection from a onemillivolt signal.

Connect the cable electrically as shown in the above drawing. Clamp the cable between pieces

of wood to the two anchor points, allowing a 76 mm sag in the center of the cable. Clamp weight(B) to cable at center of anchored span. Raise the cable by the weight to a maximum height ofthree inches above its horizontal position and permit it to drop. Monitor the output noise of thecable on the oscilloscope. Repeat the test three times and record the maximum output inmillivolts peak-to-peak.


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24 ISA-S37.10-1982 (R1995)

6.3 Ambient-pressure sensitivity shift (4.2.1.12)

Certain low-range piezoelectric pressure transducers and piezoelectric sound-pressuretransducers have different sensitivity levels at different ambient atmospheric pressures. In orderto observe this effect, the test transducer and a secondary standard transducer (whosesensitivity as a function of ambient pressure is known) shall be inserted simultaneously or

alternately into a pressure coupler calibration cavity. The static pressure in the cavity shall beestablished at a number of discrete points between 345 Pa (50 psi) and 0.69 Pa (0.1 psi) unless

a different range is specified. At each point, the frequency of excitation of the cavity shall bevaried up to the maximum frequency possible within the dimensions of the cavity whilemaintaining uniformity of instantaneous pressure within the cavity. The frequency response andsensitivity of the transducer shall be determined at each static pressure by comparison with the

output of the secondary standard transducer.

In those cases where observations of frequency response vs. ambient pressure must be made tofrequencies higher than those normally obtainable in pressure-coupler cavities, and electrostaticdriving technique may sometimes be employed (see Beranek reference). This requires that thesensitive surface of the piezoelectric pressure transducer be electrically conductive, and that thepolarizing voltage between this conductive surface and the electrostatic actuator be sufficiently

small so that arcing will not occur at low ambient pressures. Under these circumstances, the

transducer and electrostatic actuator combination may be inserted in an altitude chamber, andfrequency response measurements made directly at various ambient pressures as described in5.4.2. (The electrostatic actuator provides a pressure frequency response, as defined in 4.3).

6.4 Vibration error (4.2.1.10)

Most piezoelectric pressure transducers and piezoelectric sound-pressure transducers havesome electrical output due to vibration. In most test applications, it is essential that the output due

to the vibration environment be insignificant when compared to the output due to thecorresponding pressure environment.

Vibrate the transducer along each of the three mutually perpendicular axes, two of which lie inthe mounting plane of the transducer. The acceleration amplitudes and frequencies applied shall

be as specified (see 4.2.1.10).Depending on the specification, either sinusoidal vibration or random vibration, or both, should be

employed.

Observe the electrical output of the transducer under vibration and report the vibration error as apercent of full-scale output, or as equivalent Pa (psi) output per g.

For piezoelectric sound-pressure transducers, the equivalent SPL output due to vibration may bereported instead. This would consist of one or more curves of the equivalent SPL output of thetransducer for 1 g rms (or 1 g peak, if the type of waveform is specified) excitation, plotted as a

function of the frequency of excitation. Such curves can be computed from the vibration-inducedoutput of the transducer by the application of the transducer sensitivity level calibration.

6.5 Linear-acceleration effects (4.2.1.11.f)

Pressure transducers (dc-response only).

Place the transducer on a centrifuge, apply specified acceleration along specified axes, andmeasure changes in output. This shall establish the (linear) acceleration error of the transducer.


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ISA-S37.10-1982 (R1995) 25

6.6 Thermal sensitivity shift at maximum and minimum operating temperature(4.2.1.7)

Determine the transducer capacitance at room temperature.

Mount the transducer in a calibration coupler at ambient temperature. Determine the output

voltage of the transducer at room temperature and at a specified static pressure or at a pressurefrequency within the usable range of the pressure coupler, as applicable. Then stabilize the

transducer at the upper limit of the specified operating temperature range for at least 15 minutes.Measure the following:

a) Voltage output at maximum operating temperature with a known external capacitance.

b) Transducer capacitance at maximum operating temperature.

c) Transducer shunting resistance at maximum operating temperature.

NOTES

1. The standard which is used to establish the excitation amplitude must have known orreliably-calculable characteristics under all test conditions.

2. Allowances may have to be made for changes in cable resistance and/or cablecapacitance throughout the test temperature range.

3. Do not leave the transducer in an open-circuit condition while the temperature is beingchanged. It should be shortcircuited or connected to a preamplifier.

Allow the transducer to return again to room temperature and repeat the calibration tests of 5.2.2or 5.2.3 (whichever is applicable).

Allow the transducer to stabilize at the lower limit of the specified operating temperature range

and repeat the tests of 5.2.2 or 5.2.3 (whichever is applicable).

Allow the transducer to return again to room temperature and repeat the tests of 5.2.2 or 5.2.3(whichever is applicable).

Compute the percentage change in transducer voltage sensitivity at the two temperatureextremes compared to room temperature. Alternatively, compute the percentage change intransducer charge sensitivity at the operating temperature extremes compared with that at room

temperature.

6.7 Temperature gradient error (4.2.1.8)

Procedure I: With the transducer initially at room temperature, immerse in a suitably non-conducting liquid whose temperature is at the upper limit of the operating temperature range ofthe transducer making sure all cavities are filled. Measure and record the maximum voltage

which is generated by the transducer, and the time from the start of the transient at which thismaximum voltage is reached. If the voltage reverses and reaches a peak of opposite polarity,

record the amplitude and the time of that peak also. These voltages may be converted toequivalent Pa (psi) based upon the transducer voltage sensitivity with the specified cable.


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26 ISA-S37.10-1982 (R1995)

Procedure II: With certain low-range pressure transducers and microphones, a qualitative test

for transient temperature error may be performed as follows. Connect the transducer electricallyas it would be employed for measurement purposes. Connect the output of the transducer to anoscilloscope. Approximately two feet in front of the sensitive surface of the transducer, dischargea clear No. 25 flash bulb. Observe and record the electrical output of the transducer asequivalent Pa (psi) (or dB SPL) peak.

6.8 Sensitivity stability (4.2.1.11)

Repeat the voltage sensitivity or charge sensitivity tests for the transducer as described in 5.2.2or 5.2.3, whichever is applicable. Then perform the following:

a) Expose the transducer to its maximum rated temperature for one hour. Return to roomtemperature by allowing to cool for 24 hours. Measure and record the new sensitivity.

In extreme cases for very high temperature use, the transducer may be exposeddirectly to the flame of a torch, and heat flux measured and recorded.

b) Subject the transducer at least ten times in succession to maximum rated pressureapplied as rapidly as possible. Measure and record the new sensitivity levels 24 hours

later.

c) Expose the transducer to its minimum rated temperature for one hour. Return to roomtemperature by allowing to stabilize for 24 hours. Measure and record the new sensitivity.

Note the maximum percentage change from the original voltage sensitivity or

charge sensitivity during any portion of the above tests.

6.9 Burst Pressure (pressure transducers) (4.2.1.6)

Apply the rated burst pressure to the transducer the specified number of times and for thespecified time durations. Observe safety precautions for high range transducers. Examine formechanical damage.

7 Sample data sheets

The test data sheets included in this Standard are intended to be used for the tests described inSections 5 and 6. They consist of the following:

a) Test Summary 2 sheets

b) Individual Acceptance Test and Calibration

c) Piezoelectric Pressure Transducer Frequency Response Data (Transient Test andSinusoidal Test 2 sheets)

d) Piezoelectric Pressure Transducer Vibration Sensitivity Data


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ISA-S37.10-1982 (R1995) 27

Test Summary

Piezoelectric Pressure Transducer

Tests Star ted, Date___________

Test Finished, Date______________

Report No.: ______________ Linearity: ____________________ Test Type

Vendor: _________________ Vendor Part No.: ______________ Serial No.:

Range: _________________ Purchase Order No.: ___________ Part No.:

*Does not apply to all transducers under test.

Figure 1 Sample data sheet No. 1 (Sheet 1 of 2)

Summary of Results

Allowed

Tolerances

(% FSO)TESTTest

Procedure

ISA

S37.10

Check

if

Accep.

Failure

Error Electr. Mechan.

1 Visual Inspection 5.1

2 Sensitivity Voltage 5.2

3 Sensitivity Charge 5.2

4 Sensitivity Level (Sound Press. Trans.) 5.2.2.1

5 Proof Pressure 5.3

6 Frequency Response 5.4

7 Resonant Frequency 5.4

8 Transducer Capacitance 5.5

9 Shunting Resistance 5.6

10 Insulation Resistance 5.7

11 Transducer Cable (non-integral) 5.8 Length

Capacit.

12* Transducer Seal 6.1

13* Cable Noise 6.2

14* Ambient Pressure Sensitivity Shift 6.3

15 Vibration Error 6.4

16 Linear Acceleration Effect 6.5

17 Thermal Sensitivity Shift 6.6

18 Temperature Gradient Error 6.7

19 Sensitivity Stability 6.8

20* Burst Pressure 6.9


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ISA-S37.10-1982 (R1995) 31


*Acceleration *Measured Equivalent Output

(g) Output Output/g Pa(psi)/g dB@lg pk dB@lgrms

Z Direction

Frequency______ Hz

Frequency______ Hz

Frequency ______ Hz

Random ________

X Direction

Frequency ______ Hz

Frequency ______ Hz

Frequency ______ Hz

Random ________

Y Direction

Frequency ______ Hz

Frequency ______ Hz

Frequency ______ Hz

Random ________

Vendor's Part No.

Vendor

Report No.

Typeof Test

Diaphragm

rms * Mag. _____

Measured Outpu t inUnits of (check) _______ mV ______ pC, using peak* Mag. _____

PIEZOELECTRIC PRESSURE TRANSDUCER VIBRATION SENSITIVITY DATA

Customer's Part No.

Serial No.

Customer

Range_______ to _______ Pa (psi) _______

Z

Y

X

*Either rms or peak magnitudes maybe employed if consistency is maintained including the measurement of pressure and acceleration.


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32 ISA-S37.10-1982 (R1995)


Outputs in pC/g or mV/g** are converted to outputs in Pa/g (psi/g) from knowledge of a previous calibration in terms of mV/Pa (mV/psi)**or pC/Pa (pC/psi). Record data here if known.

Acoustic Sensitivity Level* Calibration Source

__________ mV/Pa (mV/psi) as recorded by __________________________________________________________________________

__________ pC/Pa (pC/psi) as recorded by __________________________________________________________________________

Outputs in pC/g or mVg are converted** to equivalent SPL for one g acceleration by using a previous calibration in terms of acoustic outputat a reference SPL and utilizing the relationship that the equivalent SPL at one g is:*

(reference SPL in dB) = 20 log

Record the reference SPL here if known:

Output* Calibration Source

_______________ at ______________________________ dB reference, as recorded by ______________________________________

*Either rms or peak magnitudes may be employed if consistency is maintainedfor all quantities.

**If mV/g and mV/Pa(psi) are being used, the cable capacitance should be the same in both the calibration test and the vibration test.

10

output at reference SPLacceleration


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ISA-S37.10-1982 (R1995) 33

Annex A References

AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI)

ANSI-B88.1-1971 A Guide for the Dynamic Calibration of Pressure Transducers,ASME, August, 1972

ANSI-S1.1-1960 Acoustical Terminology(R 1971)

ANSI-S1.10-1966 Method for the Calibration of Microphones(R 1971)

ANSI-S1.12-1967 Specification for Laboratory Standard Microphones(R 1972)

ANSI-S1.20-1972 Calibration of Underwater Electro-Acoustic Transducers

Available from: ANSI11 West 42nd StreetNew York, NY 10036 Tel. (212) 642-4900

ISA

ISA-S37.1-1982 Electrical Transducer Nomenclature and Terminology

ISA-S37.3-1982 Specifications and Tests for Strain Gage Pressure Transducers(R 1995)

Available from: ISA67 Alexander Drive

P.O. Box 12277Research Triangle Park, NC 27707 Tel. (919) 990-9200

MISCELLANEOUS

Beranek, L. L., Acoustic Measurements, John Wiley and Sons, New York, 1949.

Gardner, M. F., and Barnes, J. L., Transients in Linear Systems. John Wiley and Sons,New York, 1942.

Hilten J. S., Lederer P. S. and Sethian J., A Simple Hydraulic Sinusoidal Pressure

Calibrator, National Bureau of Standards, Technical Note 720, April 1972.

Perls, T. A., A Simple Objective Test for Cable Noise Due to Shock, Vibration or TransientPressure. PB 121583, Office of Technical Services, U. S. Government Printing Office,

1955.

Schweppe, J. L., et al, Methods for the Dynamic Calibration of Pressure Transducers.National Bureau of Standards Monograph 67, 12 December 1963.


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Developing and promulgating technically sound consensus standards,

recommended practices, and technical reports is one of ISA's primarygoals. To achieve this goal the Standards and Practices Departmentrelies on the technical expertise and efforts of volunteer committeemembers, chairmen, and reviewers.

ISA is an American National Standards Institute (ANSI) accredited

organization. ISA administers United States Technical AdvisoryGroups (USTAGs) and provides secretariat support for InternationalElectrotechnical Commission (IEC) and International Organization forStandardization (ISO) committees that develop process measurementand control standards. To obtain additional information on theSociety's standards program, please write:

ISAAttn: Standards Department

67 Alexander DriveP.O. Box 12277Research Triangle Park, NC 27709

ISBN: 0-87664-382-9

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