ASTM F2070-00
(Specification)Standard Specification for Transducers, Pressure and Differential, Pressure, Electrical and Fiber-Optic
Standard Specification for Transducers, Pressure and Differential, Pressure, Electrical and Fiber-Optic
SCOPE
1.1 This specification covers the requirements for pressure and differential pressure transducers for general applications.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. Where information is to be specified, it shall be stated in SI units.
1.3 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.
1.3 Special requirements for naval shipboard applications are included in Supplementary Requirements S1, S2, and S3.
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An American National Standard
Designation: F 2070 – 00
Standard Specification for
Transducers, Pressure and Differential, Pressure, Electrical
and Fiber-Optic
This standard is issued under the fixed designation F 2070; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope ANSI/ISA S37.1 shall apply, except as modified by the
definitions listed as follows:
1.1 This specification covers the requirements for pressure
3.1.1 absolute pressure—pressure measured relative to zero
and differential pressure transducers for general applications.
pressure (vacuum). (ANSI/ISA S37.1)
1.2 The values stated in SI units are to be regarded as the
3.1.2 ambient conditions—conditions such as pressure and
standard. The values given in parentheses are for information
temperature of the medium surrounding the case of the
only. Where information is to be specified, it shall be stated in
transducer. (ANSI/ISA S37.1)
SI units.
3.1.3 burst pressure—the maximum pressure applied to the
1.3 This standard does not purport to address all of the
transducer sensing element without rupture of the sensing
safety concerns, if any, associated with its use. It is the
element or transducer case as specified.
responsibility of the user of this standard to establish appro-
3.1.4 calibration—the test during which known values of
priate safety and health practices, and determine the applica-
measurands are applied to the transducer and corresponding
bility of regulatory limitations prior to use.
output readings are recorded under specified conditions.
1.4 Special requirements for naval shipboard applications
(ANSI/ISA S37.1)
are included in Supplementary Requirements S1, S2, and S3.
3.1.5 common mode pressure—the common mode pressure
2. Referenced Documents is static line pressure applied simultaneously to both pressure
sides of the transducer for the differential pressure transducer
2.1 ASTM Standards:
only.
D 3951 Practice for Commercial Packaging
3.1.6 differential pressure—the difference in pressure be-
2.2 ANSI/ISA Standards:
tween two points of measurement. (ANSI/ISA S37.1)
ANSI/ISA S37.1 Electrical Transducer Nomenclature and
3.1.7 environmental conditions—specified external condi-
Terminology
tions, such as shock, vibration, and temperature, to which a
2.3 ISO Standard:
transducer may be exposed during shipping, storage, handling,
ISO 9001 Quality System—Model for QualityAssurance in
and operation. (ANSI/ISA S37.1)
Design/Development, Production, Installation, and Ser-
3.1.8 error—the algebraic difference between the indicated
vicing
value and the true value of the measurand.
3. Terminology
(ANSI/ISA S37.1)
3.1.9 fiber-optic pressure transducer—a device that con-
3.1
verts fluid pressure, by means of changes in fiber-optic
Terms marked with (ANSI/ISA S37.1) are taken directly from
properties, to an output that is a function of the applied
ANSI/ISA S37.1 (R-1982) and are included for the conve-
measurand. The fiber-optic pressure transducer normally con-
nience of the user.Definitions—Terminology consistent with
sists of a sensor head, optoelectronics module, and connector-
ized fiber-optic cable.
3.1.10 hysteresis—themaximumdifferenceinoutput,atany
This specification is under the jurisdiction of ASTM Committee F25 on Ships
measurand value within the specified range, when the value is
and Marine Technology and is the direct responsibility of Subcommittee F25.10 on
approached first with increasing and then with decreasing
Electrical.
measurand. (ANSI/ISA S37.1)
Current edition approved Dec. 10, 2000. Published March 2001.
Annual Book of ASTM Standards, Vol 15.09.
3.1.11 insulation resistance—the resistance measured be-
Available from American National Standards Institute, 11 W. 42nd St., 13th
tween insulated portions of a transducer and between the
Floor, New York, NY 10036.
4 insulated portions of a transducer and ground when a specified
AvailablefromInternationalOrganizationforStandardization,CasePostale56,
Geneve, Switzerland CH-1211. dc voltage is applied under specified conditions.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F2070–00
3.1.12 line pressure—the pressure relative to which a dif- 3.1.32 wetted parts—transducer components with at least
ferential pressure transducer measures pressure. one surface in direct contact with the process medium.
(ANSI/ISA S37.1)
4. Classification
3.1.13 operating environmental conditions—environmental
4.1 Designation—Most transducer manufacturers use des-
conditionsduringexposuretowhichatransducermustperform
ignations or systematic numbering or identifying codes. Once
in some specified manner. (ANSI/ISA S37.1)
understood, these designations could aid the purchaser in
3.1.14 optical—involving the use of light-sensitive devices
quickly identifying the transducer type, range, application, and
to acquire information.
other parameters.
3.1.15 optical fiber—a very thin filament or fiber, made of
4.2 Design—Pressure transducers typically consist of a
dielectric materials, that is enclosed by material of lower index
sensing element that is in contact with the process medium and
of refraction and transmits light throughout its length by
a transduction element that modifies the signal from the
internal reflections.
sensing element to produce an electrical or optical output.
3.1.16 optoelectronics module—a component of the fiber-
Some parts of the transducer may be hermetically sealed if
optic pressure transducer that contains the optical source and
those parts are sensitive to and may be exposed to moisture.
detector, and signal conditioner devices necessary to convert
Pressureconnectionsmustbethreadedwithappropriatefittings
the sensed pressure to the specified output signal.
to connect the transducer to standard pipe fittings or to other
3.1.17 output—electrical or numerical quantity, produced
appropriate leak-proof fittings. The output cable must be
by a transducer or measurement system, that is a function of
securely fastened to the body of the transducer. A variety of
the applied measurand.
sensing elements are used in pressure transducers. The most
3.1.18 overpressure—the maximum magnitude of measur-
common elements are diaphragms, bellows, capsules, Bourdon
and that can be applied to a transducer without causing a
tubes, and piezoelectric crystals. The function of the sensing
change in performance beyond the specified tolerance.
element is to produce a measurable response to applied
3.1.19 pressure cycling—the specified minimum number of
pressure or vacuum. The response may be sensed directly on
specified periodic pressure changes over which a transducer
the element or a separate sensor may be used to detect element
will operate and meet the specified performance.
response. The following is a brief introduction to the major
3.1.20 pressure rating—the maximum allowable applied
pressure sensing technology design categories.
pressure of a differential pressure transducer.
4.2.1 Electrical Pressure Transducers:
3.1.21 process medium—the measured fluid (measurand) 4.2.1.1 Differential Transformer Transducer—Linear vari-
that comes in contact with the sensing element. able differential transformers (LVDT) are variable reluctance
devices. Pressure-induced sensor movement, usually transmit-
3.1.22 range—measurand values, over which a transducer
ted through a mechanical linkage, moves a core within a
is intended to measure, specified by their upper and lower
differential transformer. Sensors are most commonly bellows,
limits. (ANSI/ISA S37.1)
capsules, or Bourdon tubes. The movement of the core within
3.1.23 repeatability—ability of a transducer to reproduce
the differential transformer results in a change in reluctance
output readings when the same measurand value is applied to
that translates to a voltage output. An amplifying mechanical
it consecutively, under the same conditions, and in the same
linkage may be used to obtain adequate core movement.
direction. (ANSI/ISA S37.1)
4.2.1.2 Potentiometric Transducer—Pressure-induced
3.1.24 response—the measured output of a transducer to a
movement of the sensing element causes movement of a
specified change in measurand.
potentiometer wiper resulting in a change in resistance which
3.1.25 ripple—the peak-to-peak ac component of the dc
translates to a voltage output. A bellows or Bourdon tube is
output.
commonly used as the sensing element. An amplifying me-
3.1.26 sensing element—that part of the transducer that
chanical linkage may be used to obtain adequate wiper
responds directly to the measurand. (ANSI/ISA S37.1)
movement.
3.1.27 sensitivity factor—the ratio of the change in trans-
4.2.1.3 Strain Gage Transducer—Typical strain gage pres-
ducer output to a change in the value of the measurand.
sure transducers convert a pressure into a change in resistance
3.1.28 sensor head—the transduction element of the fiber-
due to strain which translates to a relative voltage output.
optic pressure transducer that detects fluid pressure by means
Pressure-induced movement in the sensing element deforms
of changes in optical properties.
strain elements. The strain elements of a typical strain gage
3.1.29 signal conditioner—an electronic device that makes
pressure transducer are active arms of a Wheatstone Bridge
the output signal from a transduction element compatible with
arrangement. As pressure increases, the bridge becomes elec-
a readout system.
trically unbalanced as a result of the deformation of the strain
3.1.30 static error band—static error band is the maximum
elements providing a change in voltage output.
deviation from a straight line drawn through the coordinates of
4.2.1.4 Variable Capacitance Transducer—Variable capaci-
the lower range limit at specified transducer output, and the
tance pressure transducers sense changes in capacitance with
upper range limit at specified transducer output expressed in
changes in pressure. Typically, a diaphragm is positioned
percent of transducer span.
between two stator plates. Pressure-induced diaphragm deflec-
3.1.31 transducer—device that provides a usable output in tion changes the circuit capacitance, which is detected and
response to a specified measurand. (ANSI/ISA S37.1) translated into a change in voltage output.
F2070–00
4.2.1.5 Variable Reluctance Transducer—Variable reluc- 4.5 Application—The following is provided as a general
tance pressure transducers sense changes in reluctance with comparisonofdifferenttypesoftransducersandconsiderations
for application.
changes in pressure. Typically, a diaphragm is positioned
between two ferric core coil sensors that when excited produce 4.5.1 LVDT Transducer—The sensor element may become
a magnetic field. Pressure-induced diaphragm deflection complicated depending on the amount of motion required for
core displacement. Careful consideration should be exercised
changes the reluctance, which is detected and translated to a
change in voltage output. when the application includes very low- or high-pressure
measurement, overpressure exposure, or high levels of vibra-
4.2.1.6 Piezoelectric Transducer—Piezoelectric transducers
tion. Careful consideration should also be exercised when
consist of crystals made of quartz, tourmaline, or ceramic
measuring differential pressure of process media having high
material. Pressure-induced changes in crystal electrical prop-
dielectric constants, especially liquid media. If the process
erties cause the crystal to produce an electrical output which is
media is allowed to enter the gap between the sensor element
detected and translated to a change in voltage output.
and core, accuracy may suffer. Frequency response may suffer
4.2.2 Fiber-Optic Pressure Transducers:
depending on the type of mechanical linkage(s) used in the
4.2.2.1 Fabry-Perot Interferometer—Fabry-Perot interfer-
transducer.
ometers (FPI) consist of two mirrors facing each other, the
4.5.2 Potentiometric Pressure Transducer—Potentiometric
space between the mirrors being called the cavity length. Light
pressure transducers are generally less complicated than other
reflected in the FPI is wavelength modulated in exact accor-
designs. Careful consideration should be exercised when the
dance with the cavity length. Pressure-induced movement of
application includes very low pressure measurement, overpres-
one of the mirrors causes a measurable change in cavity length
sure exposure, high levels of vibration, stability and repeatabil-
and a phase change in the reflected light signal. This change is
ity over extended periods of time, or extremely high resolution
optically detected and processed.
requirements.Frequencyresponsemaysufferdependingonthe
4.2.2.2 Bragg Grating Interferometer—A Bragg grating is type of mechanical linkage(s) used. Technological advances
have yielded more reliable designs that are commonly used.
contained in a section about 1 cm long and acts as a narrow
band filter that detects variation in the optical properties of the
4.5.3 Strain Gage Transducers—Low-level output strain
fiber. When the fiber is illuminated with an ordinary light
gage transducers are among the most common pressure trans-
source such as an LED, only a narrow band of light will be ducers. They are available in very compact packages which
reflectedbackfromthegratingsectionofthefiber.Ifapressure lend well in applications in which size is critical. Strain gage
transducers that demonstrate high degrees of accuracy and
is applied to the grating section of the fiber, the grating period
changes, and hence, the wavelength of the reflected light, excellent frequency response characteristics are readily avail-
able. Careful consideration should be exercised when the
which can be measured.
application includes very low-pressure measurement, very low
4.2.2.3 Quartz Resonators—Typically, a pair of quartz reso-
lag or delay, high vibration levels, extreme overpressure
nators are inside the pressure transducer. These are excited by
requirements, or critical stability over extended periods.
theincomingopticalsignal.Oneresonatorisload-sensitiveand
4.5.4 Variable Capacitance Transducers—Variable capaci-
vibratesatafrequencydeterminedbytheappliedpressure.The
tance transducers are well suited to measure dry, clean gases at
second resonator vibrates at a frequency that varies with the
very low pressures with a high degree of accuracy. Careful
internal temperature of the transducer. Optical frequency sig-
consideration should be exercised when measuring different
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