ASTM F2070-00(2011)
(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
ABSTRACT
This specification covers the requirements for pressure and differential pressure transducers for general applications. Pressure transducers typically consist of a sensing element that is in contact with the process medium and a transduction element that modifies the signal from the sensing element to produce an electrical or optical output. Some parts of the transducer may be hermetically sealed if those parts are sensitive to and may be exposed to moisture. Pressure connections must be threaded with appropriate fittings to connect the transducer to standard pipe fittings or to other appropriate leak-proof fittings. The output cable must be securely fastened to the body of the transducer. Most common sensing elements are diaphragms, bellows, capsules, Bourdon tubes, and piezoelectric crystals. The function of the sensing element is to produce a measurable response to applied pressure or vacuum. The response may be sensed directly on the element or a separate sensor may be used to detect element response. The following are the different types of electrical pressure transducers: differential transformed transducer, potentiometric transducer, strain gage transducer, variable reluctance transducer, and piezoelectric transducer. Different kinds of fiber-optic pressure transducers shall be discussed: Fabry-Perot interferometer, Bragg grating interferometer, quartz resonator, and micromachined membrane/diaphragm deflection. The following physical properties of transducers shall be determined: enclosure, transducer mounting, external configuration, standard electrical connection, pressure connections, damping, size, and weight. Different tests shall be conducted in order to determine the service life and overall performance of the transducers.
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.
1.4 Special requirements for naval shipboard applications are included in Supplementary Requirements S1, S2, and S3.
General Information
Relations
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:F2070 −00 (Reapproved 2011) An American National Standard
Standard Specification for
Transducers, Pressure and Differential, Pressure, Electrical
and Fiber-Optic
This standard is issued under the fixed designation F2070; 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 3.2 Definitions:
3.2.1 Terminology consistent with ANSI/ISA S37.1 shall
1.1 This specification covers the requirements for pressure
apply, except as modified by the definitions listed as follows:
and differential pressure transducers for general applications.
3.2.2 absolute pressure—pressure measured relative to zero
1.2 The values stated in SI units are to be regarded as the
pressure (vacuum). (ANSI/ISA S37.1)
standard. The values given in parentheses are for information
3.2.3 ambient conditions—conditions such as pressure and
only. Where information is to be specified, it shall be stated in
temperature of the medium surrounding the case of the
SI units.
transducer. (ANSI/ISA S37.1)
1.3 This standard does not purport to address all of the
3.2.4 burst pressure—the maximum pressure applied to the
safety concerns, if any, associated with its use. It is the
transducer sensing element without rupture of the sensing
responsibility of the user of this standard to establish appro-
element or transducer case as specified.
priate safety and health practices, and determine the applica-
bility of regulatory limitations prior to use. 3.2.5 calibration—the test during which known values of
measurands are applied to the transducer and corresponding
1.4 Special requirements for naval shipboard applications
are included in Supplementary Requirements S1, S2, and S3. output readings are recorded under specified conditions.
(ANSI/ISA S37.1)
2. Referenced Documents
3.2.6 common mode pressure—the common mode pressure
2.1 ASTM Standards:
is static line pressure applied simultaneously to both pressure
D3951Practice for Commercial Packaging
sides of the transducer for the differential pressure transducer
2.2 ANSI/ISA Standards:
only.
ANSI/ISA S37.1Electrical Transducer Nomenclature and
3 3.2.7 differential pressure—the difference in pressure be-
Terminology
tween two points of measurement. (ANSI/ISA S37.1)
2.3 ISO Standard:
ISO 9001Quality System—Model for QualityAssurance in 3.2.8 environmental conditions—specified external
conditions,suchasshock,vibration,andtemperature,towhich
Design/Development, Production, Installation, and Ser-
vicing a transducer may be exposed during shipping, storage,
handling, and operation. (ANSI/ISA S37.1)
3. Terminology
3.2.9 error—the algebraic difference between the indicated
3.1 Termsmarkedwith(ANSI/ISAS37.1)aretakendirectly
value and the true value of the measurand.
from ANSI/ISA S37.1 (R-1982) and are included for the
(ANSI/ISA S37.1)
convenience of the user.
3.2.10 fiber-optic pressure transducer—a device that con-
verts fluid pressure, by means of changes in fiber-optic
This specification is under the jurisdiction ofASTM Committee F25 on Ships
properties, to an output that is a function of the applied
and Marine Technology and is the direct responsibility of Subcommittee F25.10 on
measurand. The fiber-optic pressure transducer normally con-
Electrical.
Current edition approved April 1, 2011. Published April 2011. Originally
sists of a sensor head, optoelectronics module, and connector-
approved in 2000. Last previous edition approved in 2006 as F2070—00 (2006).
ized fiber-optic cable.
DOI: 10.1520/F2070-00R11.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
3.2.11 hysteresis—themaximumdifferenceinoutput,atany
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
measurand value within the specified range, when the value is
Standards volume information, refer to the standard’s Document Summary page on
approached first with increasing and then with decreasing
the ASTM website.
Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
measurand. (ANSI/ISA S37.1)
4th Floor, New York, NY 10036.
4 3.2.12 insulation resistance—the resistance measured be-
Available from International Organization for Standardization (ISO), 1 rue de
Varembé, Case postale 56, CH-1211, Geneva 20, Switzerland. tween insulated portions of a transducer and between the
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2070−00 (2011)
insulated portions of a transducer and ground when a specified 3.2.31 static error band—static error band is the maximum
dc voltage is applied under specified conditions. deviationfromastraightlinedrawnthroughthecoordinatesof
the lower range limit at specified transducer output, and the
3.2.13 line pressure—the pressure relative to which a dif-
upper range limit at specified transducer output expressed in
ferential pressure transducer measures pressure.
percent of transducer span.
(ANSI/ISA S37.1)
3.2.32 transducer—device that provides a usable output in
3.2.14 operating environmental conditions—environmental
response to a specified measurand. (ANSI/ISA S37.1)
conditionsduringexposuretowhichatransducermustperform
3.2.33 wetted parts—transducer components with at least
in some specified manner. (ANSI/ISA S37.1)
one surface in direct contact with the process medium.
3.2.15 optical—involving the use of light-sensitive devices
to acquire information.
4. Classification
3.2.16 optical fiber—a very thin filament or fiber, made of
4.1 Designation—Mosttransducermanufacturersusedesig-
dielectricmaterials,thatisenclosedbymaterialoflowerindex
nations or systematic numbering or identifying codes. Once
of refraction and transmits light throughout its length by
understood, these designations could aid the purchaser in
internal reflections.
quickly identifying the transducer type, range, application, and
3.2.17 optoelectronics module—a component of the fiber-
other parameters.
optic pressure transducer that contains the optical source and
4.2 Design—Pressure transducers typically consist of a
detector, and signal conditioner devices necessary to convert
sensingelementthatisincontactwiththeprocessmediumand
the sensed pressure to the specified output signal.
a transduction element that modifies the signal from the
3.2.18 output—electricalornumericalquantity,producedby
sensing element to produce an electrical or optical output.
a transducer or measurement system, that is a function of the
Some parts of the transducer may be hermetically sealed if
applied measurand.
those parts are sensitive to and may be exposed to moisture.
Pressureconnectionsmustbethreadedwithappropriatefittings
3.2.19 overpressure—the maximum magnitude of mea-
to connect the transducer to standard pipe fittings or to other
surand that can be applied to a transducer without causing a
appropriate leak-proof fittings. The output cable must be
change in performance beyond the specified tolerance.
securely fastened to the body of the transducer. A variety of
3.2.20 pressure cycling—the specified minimum number of
sensing elements are used in pressure transducers. The most
specified periodic pressure changes over which a transducer
commonelementsarediaphragms,bellows,capsules,Bourdon
will operate and meet the specified performance.
tubes, and piezoelectric crystals. The function of the sensing
3.2.21 pressure rating—the maximum allowable applied
element is to produce a measurable response to applied
pressure of a differential pressure transducer.
pressure or vacuum. The response may be sensed directly on
the element or a separate sensor may be used to detect element
3.2.22 process medium—the measured fluid (measurand)
response. The following is a brief introduction to the major
that comes in contact with the sensing element.
pressure sensing technology design categories.
3.2.23 range—measurandvalues,overwhichatransduceris
4.2.1 Electrical Pressure Transducers:
intended to measure, specified by their upper and lower limits.
4.2.1.1 Differential Transformer Transducer—Linear vari-
(ANSI/ISA S37.1)
able differential transformers (LVDT) are variable reluctance
3.2.24 repeatability—ability of a transducer to reproduce
devices. Pressure-induced sensor movement, usually transmit-
output readings when the same measurand value is applied to
ted through a mechanical linkage, moves a core within a
it consecutively, under the same conditions, and in the same
differential transformer. Sensors are most commonly bellows,
direction. (ANSI/ISA S37.1)
capsules, or Bourdon tubes. The movement of the core within
the differential transformer results in a change in reluctance
3.2.25 response—the measured output of a transducer to a
that translates to a voltage output. An amplifying mechanical
specified change in measurand.
linkage may be used to obtain adequate core movement.
3.2.26 ripple—the peak-to-peak ac component of the dc
4.2.1.2 Potentiometric Transducer—Pressure-induced
output.
movement of the sensing element causes movement of a
3.2.27 sensing element—that part of the transducer that potentiometer wiper resulting in a change in resistance which
responds directly to the measurand. (ANSI/ISA S37.1)
translates to a voltage output. A bellows or Bourdon tube is
commonly used as the sensing element. An amplifying me-
3.2.28 sensitivity factor—the ratio of the change in trans-
chanical linkage may be used to obtain adequate wiper
ducer output to a change in the value of the measurand.
movement.
3.2.29 sensor head—the transduction element of the fiber-
4.2.1.3 Strain Gage Transducer—Typical strain gage pres-
optic pressure transducer that detects fluid pressure by means
sure transducers convert a pressure into a change in resistance
of changes in optical properties.
due to strain which translates to a relative voltage output.
3.2.30 signal conditioner—an electronic device that makes Pressure-induced movement in the sensing element deforms
the output signal from a transduction element compatible with strain elements. The strain elements of a typical strain gage
a readout system. pressure transducer are active arms of a Wheatstone Bridge
F2070−00 (2011)
arrangement. As pressure increases, the bridge becomes elec- 4.3 Types—The following are common types of pressure
trically unbalanced as a result of the deformation of the strain and differential pressure transducers: pressure, differential;
elements providing a change in voltage output. pressure (gage, absolute and sealed); pressure, vacuum; and
pressure, compound.
4.2.1.4 Variable Capacitance Transducer—Variable capaci-
tance pressure transducers sense changes in capacitance with
4.4 Process Medium—The following are the most common
changes in pressure. Typically, a diaphragm is positioned
types of process media: freshwater, oil, condensate, steam,
between two stator plates. Pressure-induced diaphragm deflec-
nitrogenandotherinertgases,seawater,fluegasandammonia,
tion changes the circuit capacitance, which is detected and
and oxygen.
translated into a change in voltage output.
4.5 Application—The following is provided as a general
4.2.1.5 Variable Reluctance Transducer—Variable reluc-
comparisonofdifferenttypesoftransducersandconsiderations
tance pressure transducers sense changes in reluctance with
for application.
changes in pressure. Typically, a diaphragm is positioned
4.5.1 LVDT Transducer—The sensor element may become
betweentwoferriccorecoilsensorsthatwhenexcitedproduce
complicated depending on the amount of motion required for
a magnetic field. Pressure-induced diaphragm deflection
core displacement. Careful consideration should be exercised
changes the reluctance, which is detected and translated to a
when the application includes very low- or high-pressure
change in voltage output.
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
depending on the type of mechanical linkage(s) used in the
4.2.2 Fiber-Optic Pressure Transducers:
transducer.
4.2.2.1 Fabry-Perot Interferometer—Fabry-Perot interfer-
4.5.2 Potentiometric Pressure Transducer—Potentiometric
ometers (FPI) consist of two mirrors facing each other, the
pressure transducers are generally less complicated than other
spacebetweenthemirrorsbeingcalledthecavitylength.Light
designs. Careful consideration should be exercised when the
reflected in the FPI is wavelength modulated in exact accor-
applicationincludesverylowpressuremeasurement,overpres-
dance with the cavity length. Pressure-induced movement of
sureexposure,highlevelsofvibration,stabilityandrepeatabil-
oneofthemirrorscausesameasurablechangeincavitylength
ityoverextendedperiodsoftime,orextremelyhighresolution
and a phase change in the reflected light signal.This change is
requirements.Frequencyresponsemaysufferdependingonthe
optically detected and processed.
type of mechanical linkage(s) used. Technological advances
4.2.2.2 Bragg Grating Interferometer—A Bragg grating is
have yielded more reliable designs that are commonly used.
contained in a section about 1 cm long and acts as a narrow
4.5.3 Strain Gage Transducers—Low-level output strain
band filter that detects variation in the optical properties of the
gage transducers are among the most common pressure trans-
fiber. When the fiber is illuminated with an ordinary light
ducers. They are available in very compact packages which
source such as an LED, only a narrow band of light will be
lend well in applications in which size is critical. Strain gage
reflectedbackfromthegratingsectionofthefiber.Ifapressure
transducers that demonstrate high degrees of accuracy and
is applied to the grating section of the fiber, the grating period
excellent frequency response characteristics are readily avail-
changes, and hence, the wavelength of the reflected light,
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,apairofquartzreso-
lag or delay, hig
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.