ASTM D5720-95(2009)
(Practice)Standard Practice for Static Calibration of Electronic Transducer-Based Pressure Measurement Systems for Geotechnical Purposes (Withdrawn 2018)
Standard Practice for Static Calibration of Electronic Transducer-Based Pressure Measurement Systems for Geotechnical Purposes (Withdrawn 2018)
SIGNIFICANCE AND USE
Electronic transducer-based pressure measurement systems must be subjected to static calibration under room conditions to ensure reliable conversion from system output to pressure during use in laboratory or in field applications.
Transducer-based pressure measurement systems should be calibrated before initial use and at least quarterly thereafter and after any change in the electronic or mechanical configuration of a system.
Transducer-based pressure measurement systems should also be recalibrated if a component is dropped; overloaded; if ambient test conditions change significantly; or for any other significant changes in a system.
Static calibration is not appropriate for transducerbased systems used under operating environmental conditions involving vibration, shock, or acceleration.
SCOPE
1.1 This practice covers the procedure for static calibration of electronic transducer-based systems used to measure fluid pressures in laboratory or in field applications associated with geotechnical testing.
1.2 This practice is used to determine the accuracy of electronic transducer-based pressure measurement systems over the full pressure range of the system or over a specified operating pressure range within the full pressure range.
1.3 This practice may also be used to determine a relationship between pressure transducer system output and applied pressure for use in converting from one value to the other (calibration curve). This relationship for electronic pressure transducer systems is usually linear and may be reduced to the form of a calibration factor or a linear calibration equation.
1.4 The values stated in SI units are to be regarded as the standard. The inch-pound units in parentheses are for information only.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Specific precautionary statements are given in Section 7.
WITHDRAWN RATIONALE
This practice covers the procedure for static calibration of electronic transducer-based systems used to measure fluid pressures in laboratory or in field applications associated with geotechnical testing.
Formerly under the jurisdiction of Committee D18 on Soil and Rock, this practice was withdrawn in January 2018 in accordance with section 10.6.3 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D5720 − 95 (Reapproved 2009)
Standard Practice for
Static Calibration of Electronic Transducer-Based Pressure
Measurement Systems for Geotechnical Purposes
This standard is issued under the fixed designation D5720; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope S37.10(R1982) Specifications and Tests For Piezoelectric
Pressure and Sound-pressure Transducers
1.1 This practice covers the procedure for static calibration
of electronic transducer-based systems used to measure fluid
3. Terminology
pressures in laboratory or in field applications associated with
3.1 Terms marked with “(ANSI, ISA-S37.1)” are taken
geotechnical testing.
directly from ANSI/ISA-S37.1 (R1982) and are included for
1.2 This practice is used to determine the accuracy of
the convenience of the user.
electronic transducer-based pressure measurement systems
3.2 Definitions of Terms Specific to This Standard:
over the full pressure range of the system or over a specified
3.2.1 absolute pressure—pressure measured relative to zero
operating pressure range within the full pressure range.
pressure (vacuum) (ANSI, ISA-S37.1).
1.3 This practice may also be used to determine a relation-
3.2.2 accuracy—ratio of the error to the full-scale output or
ship between pressure transducer system output and applied
the ratio of the error to the output, as specified, expressed in
pressure for use in converting from one value to the other
percent (ANSI, ISA-S37.1).
(calibration curve). This relationship for electronic pressure
transducer systems is usually linear and may be reduced to the
3.2.3 ambient conditions—conditions (pressure,
form of a calibration factor or a linear calibration equation. temperature, etc.) of the medium surrounding the case of the
transducer (ANSI, ISA-S37.1).
1.4 The values stated in SI units are to be regarded as the
3.2.4 best straight line—line midway between the two
standard.The inch-pound units in parentheses are for informa-
tion only. parallel straight lines closest together and enclosing all output
versus measurand values on a calibration curve (ANSI, ISA-
1.5 This standard does not purport to address all of the
S37.1).
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.2.5 bonded—permanently attached over the length and
priate safety and health practices and determine the applica- width of the active element (ANSI, ISA-S37.1).
bility of regulatory limitations prior to use. Specific precau-
3.2.6 bourdon tube—pressure-sensing element consisting of
tionary statements are given in Section 7.
atwistedorcurvedtubeofnon-circularcrosssectionthattends
to be straightened by the application of internal pressure
2. Referenced Documents
(ANSI, ISA-S37.1).
2.1 ANSI/ISA Standards:
3.2.7 calibration—test during which known values of mea-
S37.1(R1982) ElectricalTransducer Nomenclature andTer-
surand are applied to the transducer and corresponding output
minology
readings are recorded under specified conditions (ANSI, ISA-
S37.3(R1982) Specifications and Tests For Strain Gauge
S37.1).
Pressure Transducers
3.2.8 calibration curve—graphical representation of the
S37.6(R1982) Specifications and Tests For Potentiometric
calibration record (ANSI, ISA-S37.1).
Pressure Transducers
3.2.9 calibration cycle—application of known values of
measurand, and recording of corresponding output readings,
This practice is under the jurisdiction of ASTM Committee D18 on Soil and
over the full (or specified portion of the) range of a transducer
Rock and is the direct responsibility of Subcommittee D18.95 on Information
in an ascending and descending direction (ANSI, ISA-S37.1).
Retrieval and Data Automation.
Current edition approved Feb. 15, 2009. Published March 2009. Originally
3.2.10 calibration record—record (for example, table or
approved in 1995. Last previous edition approved in 2002 as D5720–95 (2002).
graph) of the measured relationship of the transducer output to
DOI: 10.1520/D5720-95R09.
the applied measurand over the transducer range (ANSI,
Available from Instrument Society of America, P.O. Box 12277, Research
Triangle Park, NC 27709, http://www.isa.org. ISA-S37.1).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D5720 − 95 (2009)
3.2.11 calibration traceability—relation of a transducer 3.2.29 measurand—physicalquantity,property,orcondition
calibration, through a specified step-by-step process, to an that is measured (ANSI, ISA-S37.1).
instrument or group of instruments calibrated by the National
3.2.30 measured fluid—fluid that comes in contact with the
Institute of Standards and Technology (ANSI, ISA-S37.1).
sensing element (ANSI, ISA-S37.1).
3.2.12 capsule—pressure-sensing element consisting of two
3.2.31 normal atmospheric pressure—101.325 kPa (14.696
metallic diaphragms joined around their peripheries (ANSI,
lbf/in. ); equivalent to the pressure exerted by the weight of a
ISA-S37.1).
column of mercury 760 mm (29.92 in.) high at 0°C (32°F) at
a point on the earth where the acceleration of gravity is 9.8066
3.2.13 diaphragm—sensing element consisting of a thin,
2 2
m/s (32.1739 ft/s ).
usually circular, plate that is deformed by pressure differential
applied across the plate (ANSI, ISA-S37.1).
3.2.32 operating environmental conditions—environmental
conditionsduringexposuretowhichatransducermustperform
3.2.14 differential pressure—difference in pressure between
in some specified manner (ANSI, ISA-S37.1).
two points of measurement (ANSI, ISA-S37.1).
3.2.33 output—electricalornumericalquantity,producedby
3.2.15 end points—outputs at the specified upper and lower
a transducer or measurement system, that is a function of the
limits of the range (ANSI, ISA-S37.1).
applied measurand.
3.2.16 end-point line—straight line between the end points
3.2.34 overload—maximum magnitude of measurand that
(ANSI, ISA-S37.1).
can be applied to a transducer without causing a change in
3.2.17 end point linearity—linearity referred to the end-
performance beyond specified tolerance (ANSI, ISA-S37.1).
point line (ANSI, ISA-S37.1).
3.2.35 piezoelectric—converting a change of measurand
3.2.18 environmental conditions—specified external condi-
intoachangeintheelectrostaticchargeorvoltagegeneratedby
tions(shock,vibration,temperature,etc.)towhichatransducer
certain materials when mechanically stressed (ANSI, ISA-
may be exposed during shipping, storage, handling, and
S37.1).
operation (ANSI, ISA-S37.1).
3.2.36 piezoresistance—converting a change of measurand
3.2.19 error—algebraic difference between the indicated
into a change in resistance when mechanically stressed.
value and the true value of the measurand (ANSI, ISA-S37.1).
3.2.37 potentiometric—converting a change of measurand
3.2.20 excitation—external electrical voltage or current, or
into a voltage-ratio change by a change in the position of a
both, applied to a transducer for its proper operation (ANSI,
moveable contact on a resistance element across which exci-
ISA-S37.1).
tation is applied (ANSI, ISA-S37.1).
3.2.21 fluid—a substance, such as a liquid or gas, that is
3.2.38 range—measurandvalues,overwhichatransduceris
capable of flowing and that changes its shape at a steady rate
intended to measure, specified by their upper and lower limits
when acted upon by a force.
(ANSI, ISA-S37.1).
3.2.22 full-scale output—algebraic difference between the 3.2.39 repeatability—ability of a transducer to reproduce
end points (ANSI, ISA-S37.1).
output readings when the same measurand value is applied to
it consecutively, under the same conditions, and in the same
3.2.23 gauge pressure—pressure measured relative to am-
direction (ANSI, ISA-S37.1).
bient pressure (ANSI, ISA-S37.1).
3.2.39.1 Discussion—Repeatability is expressed as the
3.2.24 hermetically sealed—manufacturing process by
maximum difference between output readings; it is expressed
which a device is sealed and rendered airtight.
in percent of full-scale output. Two calibration cycles are used
3.2.25 hysteresis—maximum difference in output, at any
to determine repeatability unless otherwise specified.
measurand value within the specified range, when the value is
3.2.40 room conditions—ambientenvironmentalconditions,
approached first with increasing and then with decreasing
under that transducers must commonly operate, that have been
measurand (ANSI, ISA-S37.1).
established as follows: (a) temperature: 25 6 10°C (77 6
3.2.25.1 Discussion—Hysteresis is expressed in percent of
18°F); (b) relative humidity: 90% or less; and (c) barometric
full-scale output, during any one calibration cycle.
pressure: 986 10 kPa (29 6 3 in. Hg). Tolerances closer than
shownabovearefrequentlyspecifiedfortransducercalibration
3.2.26 least-squares line—straightlineforwhichthesumof
and test environments (ANSI, ISA-S37.1).
the squares of the residuals (deviations) is minimized (ANSI,
ISA-S37.1).
3.2.41 sealed gauge pressure—pressure measured relative
to normal atmospheric pressure that is sealed within the
3.2.27 leastsquareslinearity—linearityreferredtotheleast-
transducer.
squares line (ANSI, ISA-S37.1).
3.2.42 sensing element—that part of the transducer that
3.2.28 linearity—closeness of a calibration curve to a speci-
responds directly to the measurand (ANSI, ISA-S37.1).
fied straight line (ANSI, ISA-S37.1).
3.2.28.1 Discussion—Linearity is expressed as the maxi- 3.2.43 static calibration—calibrationperformedunderroom
mum deviation of any calibration point from a specified conditions and in the absence of any vibration, shock, or
straight line, during any one calibration cycle. Linearity is acceleration (unless one of these is the measurand) (ANSI,
expressed in percent of full-scale output. ISA-S37.1).
D5720 − 95 (2009)
3.2.44 strain gauge—converting a change of measurand may be either individual pressure transducers, as described in
into a change in resistance due to strain (ANSI, ISA-S37.1). 6.2, with independent power supplies, signal conditioners, and
readout systems or the systems may be self-contained instru-
3.2.45 theoretical output—product of the applied pressure
ments such as pressure meters or pressure monitors, as de-
or vacuum and the ratio of full-scale output to calibrated
scribed in 6.7.3.1.
pressure range.
6.2 Pressure Transducers—Pressure transducers usually
3.2.46 transducer—device that provides a usable output in
consist of a sensing element that is in contact with the
response to a specified measurand (ANSI, ISA-S37.1).
measured fluid and a transduction element that modifies the
3.2.47 transduction element—electrical portion of a trans-
signal from the sensing element to produce an output. The
ducer in which the output originates (ANSI, ISA-S37.1).
materials used in the sensing element must be compatible with
3.2.48 warm-up period—period of time, starting with the
the measured fluid. Some parts of the transducer may be
application of excitation to the transducer, required to ensure
hermetically sealed if those parts are sensitive to and may be
that the transducer will perform within all specified tolerances
exposed to moisture. Pressure connectors must be threaded
(ANSI, ISA-S37.1).
with appropriate fittings to attach the transducer to standard
pipe fittings, or to other appropriate leakproof fittings. The
4. Summary of Practice
output cable must be securely fastened to the body of the
4.1 Apressure transducer based measurement system (pres-
transducer.Asimpleschematicofagenericpressuretransducer
sure transducer, readout system, power supply, and signal
is shown in Fig. 1.
conditioner), pressure standard, and appropriate controllers,
6.2.1 Sensing Elements—A wide variety of sensing ele-
regulators, and valves are connected to pressure or vacuum
ments are used in pressure transducers. The most common
sources, or both.
elements are diaphragms, capsules, bourdon tubes, and piezo-
electric crystals. The function of the sensing element is to
4.2 Pressure or vacuum is applied in predetermined inter-
valsoverthefullrange(oraspecifiedportionofthefullrange) produce a measurable response to applied pressure. The
response may be sensed directly on the element or a separate
of the pressure measurement system.
sensor may be used to detect element response.
4.3 Thepressuremeasurementsystemoutputiscomparedat
6.2.2 Diaphragms—Diaphragmsareusuallyplates,disks,or
each pressure or vacuum interval to the applied pressure or
wafersofstainlesssteel,silicon,crystal,orceramicthatdeflect
vacuum as indicated by the pressure standard.
when subjected to pressure. Deflection of the diaphragm is
4.4 The error in pressure measurement system output is
detected by sensors.
calculated for each pressure or vacuum interval over the
6.2.2.1 Strain-Gauged Diaphragms—The most common
calibrated range.
diaphragm deflection sensor is the strain gauge. Strain gages
canbebondedtothediaphragmorimbeddedinthediaphragm.
4.5 From error, the accuracy of the pressure measurement
Terms typically used to describe these sensors are bonded foil
system is computed and a determination is made to accept or
straingages,bondedsemiconductorstraingages,sputteredthin
reject the pressure measurement system.
filmstraingages,diffusedsemiconductorstraingages,molecu-
4.6 From a calibration curve, a relationship between system
larly diffused strain gages, piezoresistive strain gages, or
output and applied pressure may be determined.
silicon chips.
6.2.2.2 Mechanically Linked Diaphragms— Mechanically
5. Significance and Use
linked diaphragms use sensors which are physically separate
5.1 Electronic transducer-based pressure measurement sys-
from the diaphragm.Awide variety of sensors are used in this
tems must be subjected to static calibration under room
style element. Sensors may include cantilever beams or
conditions to ensure reliable conversion from system output to
bridges, linear displacement transducers (LDT),
pressure during use in laboratory or in field applications.
potentiometers, or vibrating wires. Beams and bridges are
5.2 Transducer-basedpressuremeasurementsystemsshould
typicallystrain-gagedsensorsandtermssuchassemiconductor
be calibrated before initial use and at least quarterly thereafter
strain-gauge sensing beam and sputtered strain-gauge bridge
and after any change in the electronic or mechanical configu-
are used with these devices. The LVDT, LDT, and potentiom-
ration of a system.
eter transducers use a rod or a rod-sweeper assembly attached
to a diaphragm to sense deflectio
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