ASTM E1137/E1137M-08(2014)

Standard Specification for Industrial Platinum Resistance Thermometers

ABSTRACT
This specification establishes the physical, performance, and testing requirements, as well as resistance-temperature relationship and tolerances for metal-sheathed industrial platinum resistance thermometers (PRT) suitable for direct immersion temperature measurement. All materials including the sheath materials, sensing elements, insulation, connecting wire end closure materials, epoxy materials, and connecting wires shall be in accordance with specified requirements. The PRT shall be subjected to corresponding qualification tests to demonstrate conformance to the acceptance criteria of the following properties: insulation resistance; resistance versus temperature; minimum immersion length; pressure; thermal response time; vibration; self-heating; stability; thermoelectric effect; mechanical shock; and dimensions.
SIGNIFICANCE AND USE
4.1 This specification is written to provide common terminology, resistance versus temperature characteristics, accuracy classification, and inspection requirements for a specified configuration of a typical industrial platinum resistance thermometer (PRT).  
4.2 This specification may be used as part of the documentation to support negotiations for the purchase and discussion of such thermometers.
SCOPE
1.1 This specification covers the requirements for metal-sheathed industrial platinum resistance thermometers (PRT's) suitable for direct immersion temperature measurement. It applies to PRT's with an average temperature coefficient of resistance between 0 and 100°C of 0.385 %/°C and nominal resistance at 0°C of 100 Ω or other specified value. This specification covers PRT's suitable for all or part of the temperature range −200 to 650°C. The resistance-temperature relationship and tolerances are specified as well as physical, performance, and testing requirements.  
1.2 The values of temperature in this specification are based on the International Temperature Scale of 1990 (ITS-90).2  
1.3 The values stated in inch-pound units or SI (metric) units may be regarded separately as standard. The values stated in each system are not exact equivalents, and each system shall be independent of the other.  
1.4 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.

General Information

• Status: Historical
• Publication Date: 30-Nov-2014
• ICS: 17.200.20 - Temperature-measuring instruments
• Technical Committee: E20 - Temperature Measurement
• Drafting Committee: E20.03 - Resistance Thermometers

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:E1137/E1137M −08 (Reapproved 2014)
Standard Specification for
Industrial Platinum Resistance Thermometers
ThisstandardisissuedunderthefixeddesignationE1137/E1137M;thenumberimmediatelyfollowingthedesignationindicatestheyear
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 Chromium-TungstenAlloy (UNS N06674) Seamless Pipe
and Tube
1.1 This specification covers the requirements for metal-
E344Terminology Relating to Thermometry and Hydrom-
sheathed industrial platinum resistance thermometers (PRT’s)
etry
suitable for direct immersion temperature measurement. It
E644Test Methods for Testing Industrial Resistance Ther-
applies to PRT’s with an average temperature coefficient of
mometers
resistance between 0 and 100°C of 0.385%⁄°C and nominal
E1652Specification for Magnesium Oxide and Aluminum
resistance at 0°C of 100 Ω or other specified value. This
Oxide Powder and Crushable Insulators Used in the
specification covers PRT’s suitable for all or part of the
Manufacture of Base Metal Thermocouples, Metal-
temperature range−200 to 650°C. The resistance-temperature
Sheathed Platinum Resistance Thermometers, and Noble
relationship and tolerances are specified as well as physical,
Metal Thermocouples
performance, and testing requirements.
1.2 Thevaluesoftemperatureinthisspecificationarebased
3. Terminology
on the International Temperature Scale of 1990 (ITS-90).
3.1 Definitions—For definitions of terms used in this speci-
1.3 The values stated in inch-pound units or SI (metric)
fication see Terminology E344.
unitsmayberegardedseparatelyasstandard.Thevaluesstated
3.2 Definitions of Terms Specific to This Standard:
ineachsystemarenotexactequivalents,andeachsystemshall
3.2.1 connecting wire end closure, n—moisture barrier at
be independent of the other.
the connecting wire end of the sheath.
1.4 This standard does not purport to address all of the
3.2.1.1 Discussion—The closure is intended to provide a
safety concerns, if any, associated with its use. It is the
sealsufficienttopreventthesensor’sinsulationresistancefrom
responsibility of the user of this standard to establish appro-
dropping below the minimum requirements.
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
3.2.2 connecting wires, n—wires that run from the element
through the connecting wire end closure and external to the
2. Referenced Documents
sheath.
2.1 ASTM Standards:
3.2.3 excitation, n—electrical current passing through the
A269Specification for Seamless and Welded Austenitic
element.
Stainless Steel Tubing for General Service
3.2.4 g-level, n—acceleration of an object relative to the
B167Specification for Nickel-Chromium-IronAlloys (UNS
local acceleration of gravity.
N06600, N06601, N06603, N06690, N06693, N06025,
3.2.4.1 Discussion—For example, a g-level of 5 is equiva-
N06045, and N06696), Nickel-Chromium-Cobalt-
lent to an acceleration of approximately 5×9.8 m/s =49.0
Molybdenum Alloy (UNS N06617), and Nickel-Iron-
m/s .
3.2.5 minimum immersion length, n—depth that a thermom-
This specification is under the jurisdiction of ASTM Committee E20 on
eter should be immersed, in a uniform temperature
Temperature Measurement and is the direct responsibility of Subcommittee E20.03
environment, such that further immersion does not produce a
on Resistance Thermometers.
change in indicated temperature greater than the specified
Current edition approved Dec. 1, 2014. Published December 2014. Originally
approved in 1987. Last previous edition approved in 2008 as E1137–08. DOI:
tolerance.
10.1520/E1137_E1137M-08R14.
3.2.6 PRT design, n—generic term used to differentiate
Preston-Thomas, H., “The International Temperature Scale of 1990 (ITS-90),”
Metrologia , Vol 27, No. 1. 1990, pp 3– 10, ibid, Vol 27, No. 2, 1990, p107
between different PRT construction details, such as element
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and connecting wire construction, insulation methods, sealing
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
techniques,andmountingmethods(forexample,springloaded
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. or direct mounting).
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1137/E1137M−08 (2014)
3.2.7 self-heating, n—change in temperature of the element 6.1.9 Serial Number identification requirement (mandatory
caused by the heating effect of the excitation. if an individual calibration or test record will be maintained).
3.2.8 sheath, n—cylindrical metal tube with an integral
7. Materials and Manufacture
welded closure at the end in which the element is located.
7.1 All materials used shall be in accordance with the
4. Significance and Use following requirements:
7.1.1 Sheath Materials—For temperatures not exceeding
4.1 This specification is written to provide common
480°C, austenitic stainless steel tubing, conforming to Speci-
terminology, resistance versus temperature characteristics, ac-
fication A269. For temperatures not exceeding 650°C, high-
curacy classification, and inspection requirements for a speci-
nickel alloy tubing, conforming to Specification B167.
fied configuration of a typical industrial platinum resistance
7.1.2 Sensing Element—Sensing element shall be platinum.
thermometer (PRT).
7.1.3 Insulation—The insulating material within the PRT
4.2 This specification may be used as part of the documen-
shall be compatible with the temperature range−200 to 650°C
tation to support negotiations for the purchase and discussion
or as specified in 6.1.4. Magnesium oxide (MgO) and alumi-
of such thermometers.
numoxide(Al O )powdersandcrushableinsulatorsconform-
2 3
ing to Specification E1652 satisfy this requirement.
5. Classification of Tolerances
7.1.4 Connecting Wire End Closure Materials—Closure
5.1 The PRT shall conform to the resistance-temperature
materialsshallprovideabarrieragainstwaterandotherliquids
relation (see 9.2.1) within the following tolerances:
and generally prevent the penetration of water vapor. Any
material used shall be compatible with the ambient tempera-
Grade A56@0.1310.0017? t ? #°C (1)
tures specified for the application (see 6.1.5).
Grade B56 0.2510.0042 ? t ? °C (2)
@ #
7.1.4.1 Typically, epoxy materials are used for ambient
where:
temperatureslessthan200°Candmoistureimperviousceramic
adhesives are used over 200°C, but the connecting wire end
| t | = value of temperature without regard to sign, °C.
closureshallnotbelimitedtothesematerialsiftheendclosure
5.1.1 The tolerances are given in Table 1 for a PRT with a
meets all other requirements of this specification.
nominal resistance of 100 Ω at 0°C.
7.1.5 Connecting Wires—Typically, materials of connecting
wiresare:nickelplatedcopper,nickel,platinum,constantan,or
6. Ordering Information
manganin. Individual connecting wires may be comprised of
6.1 The purchase order documents shall specify the follow-
two or more different materials and sizes over their length to
inginformationtoensurethatthePRTisadequatelydescribed:
accommodate different requirements internal and external to
6.1.1 The number of this specification,
thesensorsheath.Wheredifferentmaterialsareused,caremust
6.1.2 Sheath diameter and overall length (see Fig. 1),
be exercised in their selection to minimize thermoelectrically
6.1.3 Sheath material,
induced measurement error (see 9.6). Any material used in
6.1.4 Minimum and maximum sensed temperature,
joining the connecting wires to the PRT element must with-
6.1.5 Maximum and minimum temperature at connecting
stand the maximum operating temperature of the PRT.
wire end closure,
6.1.6 Connection configuration; 2-Wire, 3-Wire, 4-Wire
8. Other Requirements
(potentiometric), and compensating loop (4-Wire) (see Fig. 2),
8.1 Pressure—The PRTshall withstand an external pressure
6.1.7 Tolerance, (Grade A, or Grade B),
of 21 MPa (3000 psig) and shall be tested in accordance with
6.1.8 Nominal resistance at 0°C (100 Ω unless otherwise
Test Methods E644 pressure test.The PRTshall remain within
specified), and
the tolerance specified in 5.1.
8.2 Vibration:
A, B
8.2.1 ThePRTshallwithstandvibrationtestingasdescribed
TABLE 1 Classification Tolerances
in Test Methods E644 using the test parameters in Table 2.
Temperature, t,
Grade A Grade B
°C
8.2.2 The PRT shall be mounted by installation in the
°C Ω °C Ω
thermowell or by threaded connection to simulate normal
− 200 0.47 0.20 1.1 0.47
mounting procedure as limited by Table 2.
− 100 0.30 0.12 0.67 0.27
8.2.3 The PRT shall be continuously energized with an
0 0.13 0.05 0.25 0.10
100 0.30 0.11 0.67 0.25
oscilloscope-monitored 1.0-mA dc excitation. There shall be
200 0.47 0.17 1.1 0.40
no discontinuity of the monitored trace during the test.
300 0.64 0.23 1.5 0.53
8.2.4 After the PRT is tested for vibration the insulation
400 0.81 0.28 1.9 0.66
500 0.98 0.33 2.4 0.78
resistanceofthePRTshallremainwithinthetoleranceofTable
600 1.15 0.37 2.8 0.89
3andtheresistanceat0°Cwithinthetolerancespecifiedin5.1.
650 1.24 0.40 3.0 0.94
A
The table represents values for 3-wire and 4-wire PRT’s. Caution must be 8.3 Mechanical Shock:
exercised with 2-wire PRT’s because of possible errors caused by connecting
8.3.1 The PRT shall withstand mechanical shock testing as
wires.
B describedinTestMethodsE644.Thehalf-sinepulseshallhave
Tabulated values are based on elements of 100.0 Ω (nominal) at 0°C.
a peak g-level of 50 and duration of 11 ms.
E1137/E1137M−08 (2014)
FIG. 1 Typical Industrial Platinum Resistance Thermometer
FIG. 2 Connection Configurations
TABLE 2 Vibration Test Parameters
8.4.1 ThePRTshallbecapableofcontinuousoperationover
the specified temperature range (see 6.1).
NOTE 1— The values in Table 2 apply to a PRT mounted in a
8.4.2 Theconnectingwireendclosureandexternalconnect-
thermowell with nominal diametral clearance of less than 0.25 mm (0.01
in.).IfthePRTisnotmountedinathermowell,thevaluesinTable2apply
ing wires need not withstand the entire PRT operating tem-
to a PRT with an unsupported stem length less than 100 mm (4 in.).
perature range.As a minimum, these materials must withstand
Frequency 5 to 500 Hz
the ambient temperature limits specified for the application
Test Level 1.27-mm (0.05-in.) double amplitude displacement or
(see 6.1.5).
peak g-level of 3, whichever is less
Resonant Dwell Time 30 min for each resonant point
Cycling Time 3 h per axis less the time spent at resonant dwells at
9. Performance
the axis.
Mounting As normally mounted including the mating thermowell,
9.1 Excitation:
if applicable.
9.1.1 The PRT must be constructed such that it is usable in
ac or dc measurement systems. In ac measuring systems,
reactance effects shall be considered.
TABLE 3 Insulation Resistance
9.1.2 ThePRTshallbecapableofoperatingwithcontinuous
Applied dc Voltage, Volts dc Minimum Insulation Resistance
excitation of 10 mA. However, excitation of 1 mA or less is
min max °C MΩ
10 50 25 ± 5 100 recommendedtominimizemeasurementerrorsassociatedwith
10 50 300 ± 10 10
self-heating (see 9.4).
10 50 650 ± 15 2
9.2 Resistance versus Temperature Relation:
9.2.1 Resistance-Temperature Equations—Within the speci-
fied tolerances (see 5.1), the PRT shall have resistance-
temperature characteristics defined as follows:
8.3.2 The PRT shall be continuously energized with an
for the range−200°C ≤ t < 0°C:
oscilloscope-monitored 1.0-mA dc excitation. There shall be
2 3
R 5 R 11At1Bt 1C t 2 100 t Ω (3)
@ ~ ! #
t o
no discontinuity of the monitored trace during the test.
for the range 0°C ≤ t ≤ 650°C:
8.3.3 After the PRT is tested for mechanical shock, the
insulation resistance of the PRT shall remain within the 2
R 5 R @11At1Bt # Ω (4)
t o
tolerance of Table 3 and the resistance at 0°C within the
where:
tolerance in 5.1.
t = temperature (ITS-90), °C,
8.4 Thermal:
E1137/E1137M−08 (2014)
10. Dimensions, Mass, and Permissible Variations
R = resistance at temperature (t),
t
R = resistance at 0°C,
o
10.1 A PRT without a process fitting or other means of
−3 −1
A = 3.9083×10 °C ,
attachment is shown in Fig. 1.
−7 −2
B = −5.775×10 °C , and
−12 −4
10.2 PRT’s manufactured in accordance with this specifica-
C = −4.183×10 °C .
tion shall be able to pass through the straightness ring gauge
9.2.2 Resistance Table—Resistance values of the PRT ver-
with the gauge sizes listed in Table 6.
sus temperature using the equations of 9.2.1 and R of 100 Ω
o
are given in Table 4.
11. Required Tests
9.2.3 Inverse equations that may be used to compute values
11.1 Qualification Tests—The PRT shall be subjected to the
of temperature (°C) as a function of resistance are given in
tests outlined in Table 7 to demonstrate conformance to this
Appendix X1.
specification. The manufacturer shall perform these tests at
9.3 Insulation Resistance—The insulation resistance be-
least one time to qualify the PRT design. Thereafter, it is
tween each connecting wire and the sheath shall meet the
recommended these tests be used on a periodic basis to verify
requirements of Table 3 when tested in accordance with Test
process control.
Methods E644. The PRT shall be tested with at least the
11.1.1 Qualification Test Report—The manufacturer shall
minimum immersion length exposed to the temperature envi-
prepare and retain a qualification test report applicable to the
ronment.
PRT design that documents the model number, test procedure
(byreferencetoTestMethodsE644andthisspecification),and
9.4 Self-Heating—A power of at least 33 mW shall be
the results obtained.
required to produce a self-heating of 1°C when the PRT is
tested in water in accordance with Test Methods E644.
11.2 Acceptance Tests—The manufacturer shall verify that
the PRT to be delivered satisfies the following minimum test
9.5 Thermal Response Time—The 63.2% response time
requirements: resistance at 0°C (see 5.1), room temperature
shall not exceed the values in Table 5 when determined in
insulation resistance (see 9.3), and dimensions (see 10.2).
accordance with Test Methods E644. The step change in
temperature shall be from 20 6 5°C air to 77 6 5°C water
NOTE 2—The purchaser may perform any of the tests included in Table
flowing at 0.9 6 0.09 m/s (3.0 6 0.3 ft/s).
7 as a basis for acceptance or rejection.
9.6 Thermoelectric Effect—Whentestedinaccordancewith
12. Declaration of Conformity
Test Methods E644 at the upper operating temperature, the
12.1 The manufacturer shall provide a document to the
PRTsha
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: E1137/E1137M − 08 E1137/E1137M − 08 (Reapproved 2014)
Standard Specification for
Industrial Platinum Resistance Thermometers
This standard is issued under the fixed designation E1137/E1137M; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers the requirements for metal-sheathed industrial platinum resistance thermometers (PRT’s) suitable
for direct immersion temperature measurement. It applies to PRT’s with an average temperature coefficient of resistance between
0 and 100 °C 100°C of 0.385 % ⁄°C and nominal resistance at 0 °C 0°C of 100 Ω or other specified value. This specification covers
PRT’s suitable for all or part of the temperature range −200 to 650 °C. 650°C. The resistance-temperature relationship and
tolerances are specified as well as physical, performance, and testing requirements.
1.2 The values of temperature in this specification are based on the International Temperature Scale of 1990 (ITS-90).
1.3 The values stated in inch-pound units or SI (metric) units may be regarded separately as standard. The values stated in each
system are not exact equivalents, and each system shall be independent of the other.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
A269 Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service
B167 Specification for Nickel-Chromium-Iron Alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045,
and N06696), Nickel-Chromium-Cobalt-Molybdenum Alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten Alloy
(UNS N06674) Seamless Pipe and Tube
E344 Terminology Relating to Thermometry and Hydrometry
E644 Test Methods for Testing Industrial Resistance Thermometers
E1652 Specification for Magnesium Oxide and Aluminum Oxide Powder and Crushable Insulators Used in the Manufacture of
Base Metal Thermocouples, Metal-Sheathed Platinum Resistance Thermometers, and Noble Metal Thermocouples
3. Terminology
3.1 Definitions—For definitions of terms used in this specification see Terminology E344.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 connecting wire end closure, n—moisture barrier at the connecting wire end of the sheath.
This specification is under the jurisdiction of ASTM Committee E20 on Temperature Measurement and is the direct responsibility of Subcommittee E20.03 on Resistance
Thermometers.
Current edition approved Nov. 1, 2008Dec. 1, 2014. Published December 2008December 2014. Originally approved in 1987. Last previous edition approved in 20042008
as E1137 – 04.E1137 – 08. DOI: 10.1520/E1137_E1137M-08.10.1520/E1137_E1137M-08R14.
Preston-Thomas, H., “The International Temperature Scale of 1990 (ITS-90),” Metrologia , Vol 27, No. 1. 1990, pp 3– 10, ibid, Vol 27, No. 2, 1990, p107
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.2.1.1 Discussion—
The closure is intended to provide a seal sufficient to prevent the sensor’s insulation resistance from dropping below the minimum
requirements.
3.2.2 connecting wires, n—wires that run from the element through the connecting wire end closure and external to the sheath.
3.2.3 excitation, n—electrical current passing through the element.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1137/E1137M − 08 (2014)
3.2.4 g-level, n—acceleration of an object relative to the local acceleration of gravity.
3.2.4.1 Discussion—
2 2
For example, a g-level of 5 is equivalent to an acceleration of approximately 5 × 9.8 m/s = 49.0 m/s .
3.2.5 minimum immersion length, n—depth that a thermometer should be immersed, in a uniform temperature environment,
such that further immersion does not produce a change in indicated temperature greater than the specified tolerance.
3.2.6 PRT design, n—generic term used to differentiate between different PRT construction details, such as element and
connecting wire construction, insulation methods, sealing techniques, and mounting methods (for example, spring loaded or direct
mounting).
3.2.7 self-heating, n—change in temperature of the element caused by the heating effect of the excitation.
3.2.8 sheath, n—cylindrical metal tube with an integral welded closure at the end in which the element is located.
4. Significance and Use
4.1 This specification is written to provide common terminology, resistance versus temperature characteristics, accuracy
classification, and inspection requirements for a specified configuration of a typical industrial platinum resistance thermometer
(PRT).
4.2 This specification may be used as part of the documentation to support negotiations for the purchase and discussion of such
thermometers.
5. Classification of Tolerances
5.1 The PRT shall conform to the resistance-temperature relation (see 9.2.1) within the following tolerances:
Grade A 56 0.1310.0017? t ? °C (1)
@ #
Grade B 56 0.2510.0042 ? t ? °C (2)
@ #
where:
| t | = value of temperature without regard to sign, °C.
5.1.1 The tolerances are given in Table 1 for a PRT with a nominal resistance of 100 Ω at 0 °C. 0°C.
6. Ordering Information
6.1 The purchase order documents shall specify the following information to ensure that the PRT is adequately described:
6.1.1 The number of this specification,
6.1.2 Sheath diameter and overall length (see Fig. 1),
6.1.3 Sheath material,
6.1.4 Minimum and maximum sensed temperature,
6.1.5 Maximum and minimum temperature at connecting wire end closure,
6.1.6 Connection configuration; 2-Wire, 3-Wire, 4-Wire (potentiometric), and compensating loop (4-Wire) (see Fig. 2),
6.1.7 Tolerance, (Grade A, or Grade B),
6.1.8 Nominal resistance at 0 °C 0°C (100 Ω unless otherwise specified), and
6.1.9 Serial Number identification requirement (mandatory if an individual calibration or test record will be maintained).
A, B
TABLE 1 Classification Tolerances
Temperature, t,
Grade A Grade B
°C
°C Ω °C Ω
− 200 0.47 0.20 1.1 0.47
− 100 0.30 0.12 0.67 0.27
0 0.13 0.05 0.25 0.10
100 0.30 0.11 0.67 0.25
200 0.47 0.17 1.1 0.40
300 0.64 0.23 1.5 0.53
400 0.81 0.28 1.9 0.66
500 0.98 0.33 2.4 0.78
600 1.15 0.37 2.8 0.89
650 1.24 0.40 3.0 0.94
A
The table represents values for 3-wire and 4-wire PRT’s. Caution must be
exercised with 2-wire PRT’s because of possible errors caused by connecting
wires.
B
Tabulated values are based on elements of 100.0 Ω (nominal) at 0 °C.0°C.
E1137/E1137M − 08 (2014)
FIG. 1 Typical Industrial Platinum Resistance Thermometer
FIG. 2 Connection Configurations
7. Materials and Manufacture
7.1 All materials used shall be in accordance with the following requirements:
7.1.1 Sheath Materials—For temperatures not exceeding 480 °C, 480°C, austenitic stainless steel tubing, conforming to
Specification A269. For temperatures not exceeding 650 °C, 650°C, high-nickel alloy tubing, conforming to Specification B167.
7.1.2 Sensing Element—Sensing element shall be platinum.
7.1.3 Insulation—The insulating material within the PRT shall be compatible with the temperature range −200 °C to 650 °C
650°C or as specified in 6.1.4. Magnesium oxide (MgO) and aluminum oxide (Al O ) powders and crushable insulators
2 3
conforming to Specification E1652 satisfy this requirement.
7.1.4 Connecting Wire End Closure Materials—Closure materials shall provide a barrier against water and other liquids and
generally prevent the penetration of water vapor. Any material used shall be compatible with the ambient temperatures specified
for the application (see 6.1.5).
7.1.4.1 Typically, epoxy materials are used for ambient temperatures less than 200 °C 200°C and moisture impervious ceramic
adhesives are used over 200 °C, 200°C, but the connecting wire end closure shall not be limited to these materials if the end closure
meets all other requirements of this specification.
7.1.5 Connecting Wires—Typically, materials of connecting wires are: nickel plated copper, nickel, platinum, constantan, or
manganin. Individual connecting wires may be comprised of two or more different materials and sizes over their length to
accommodate different requirements internal and external to the sensor sheath. Where different materials are used, care must be
exercised in their selection to minimize thermoelectrically induced measurement error (see 9.6). Any material used in joining the
connecting wires to the PRT element must withstand the maximum operating temperature of the PRT.
8. Other Requirements
8.1 Pressure—The PRT shall withstand an external pressure of 21 MPa (3000 psig) and shall be tested in accordance with Test
Methods E644 pressure test. The PRT shall remain within the tolerance specified in 5.1.
8.2 Vibration:
8.2.1 The PRT shall withstand vibration testing as described in Test Methods E644 using the test parameters in Table 2.
8.2.2 The PRT shall be mounted by installation in the thermowell or by threaded connection to simulate normal mounting
procedure as limited by Table 2.
8.2.3 The PRT shall be continuously energized with an oscilloscope-monitored 1.0-mA dc excitation. There shall be no
discontinuity of the monitored trace during the test.
E1137/E1137M − 08 (2014)
TABLE 2 Vibration Test Parameters
NOTE 1— The values in Table 2 apply to a PRT mounted in a
thermowell with nominal diametral clearance of less than 0.25 mm (0.01
in.). If the PRT is not mounted in a thermowell, the values in Table 2 apply
to a PRT with an unsupported stem length less than 100 mm (4 in.).
Frequency 5 to 500 Hz
Test Level 1.27-mm (0.05-in.) double amplitude displacement or
peak g-level of 3, whichever is less
Resonant Dwell Time 30 min for each resonant point
Cycling Time 3 h per axis less the time spent at resonant dwells at
the axis.
Mounting As normally mounted including the mating thermowell,
if applicable.
8.2.4 After the PRT is tested for vibration the insulation resistance of the PRT shall remain within the tolerance of Table 3 and
the resistance at 0 °C 0°C within the tolerance specified in 5.1.
8.3 Mechanical Shock:
8.3.1 The PRT shall withstand mechanical shock testing as described in Test Methods E644. The half-sine pulse shall have a
peak g-level of 50 and duration of 11 ms.
8.3.2 The PRT shall be continuously energized with an oscilloscope-monitored 1.0-mA dc excitation. There shall be no
discontinuity of the monitored trace during the test.
8.3.3 After the PRT is tested for mechanical shock, the insulation resistance of the PRT shall remain within the tolerance of
Table 3 and the resistance at 0 °C 0°C within the tolerance in 5.1.
8.4 Thermal:
8.4.1 The PRT shall be capable of continuous operation over the specified temperature range (see 6.1).
8.4.2 The connecting wire end closure and external connecting wires need not withstand the entire PRT operating temperature
range. As a minimum, these materials must withstand the ambient temperature limits specified for the application (see 6.1.5).
9. Performance
9.1 Excitation:
9.1.1 The PRT must be constructed such that it is usable in ac or dc measurement systems. In ac measuring systems, reactance
effects shall be considered.
9.1.2 The PRT shall be capable of operating with continuous excitation of 10 mA. However, excitation of 1 mA or less is
recommended to minimize measurement errors associated with self-heating (see 9.4).
9.2 Resistance versus Temperature Relation:
9.2.1 Resistance-Temperature Equations—Within the specified tolerances (see 5.1), the PRT shall have resistance-temperature
characteristics defined as follows:
for the range −200 °C range −200°C ≤ t < 0 °C: 0°C:
2 3
R 5 R 11At1Bt 1C t 2 100 t Ω (3)
@ ~ ! #
t o
for the range 0 °C 0°C ≤ t ≤ 650 °C: 650°C:
R 5 R @11At1Bt # Ω (4)
t o
where:
t = temperature (ITS-90), °C,
R = resistance at temperature (t),
t
R = resistance at 0 °C,
o
R = resistance at 0°C,
o
−3 −1
A = 3.9083 × 10 °C ,
−7 -2
B = −5.775 × 10 °C , and
−7 −2
B = −5.775 × 10 °C , and
−12 −4
C = −4.183 × 10 °C .
TABLE 3 Insulation Resistance
Applied dc Voltage, Volts dc Minimum Insulation Resistance
min max °C MΩ
10 50 25 ± 5 100
10 50 300 ± 10 10
10 50 650 ± 15 2
E1137/E1137M − 08 (2014)
9.2.2 Resistance Table—Resistance values of the PRT versus temperature using the equations of 9.2.1 and R of 100 Ω are given
o
in Table 4.
9.2.3 Inverse equations that may be used to compute values of temperature (°C) as a function of resistance are given in
Appendix X1.
9.3 Insulation Resistance—The insulation resistance between each connecting wire and the sheath shall meet the requirements
of Table 3 when tested in accordance with Test Methods E644. The PRT shall be tested with at least the minimum immersion length
exposed to the temperature environment.
9.4 Self-Heating—A power of at least 33 mW shall be required to produce a self-heating of 1 °C 1°C when the PRT is tested
in water in accordance with Test Methods E644.
9.5 Thermal Response Time—The 63.2 % response time shall not exceed the values in Table 5 when determined in accordance
with Test Methods E644. The step change in temperature shall be from 20 6 5 °C 5°C air to 77 6 5 °C 5°C water flowing at 0.9
6 0.09 m/s (3.0 6 0.3 ft/s).
9.6 Thermoelectric Effect— When tested in accordance with Test Methods E644 at the upper operating temperature, the PRT
shall remain within the tolerances specified in 5.1 with an excitation current of 1-mA dc 6 15 %, regardless of polarity.
NOTE 1—Internal and external connecting wire composition, wire inhomogeneity, and temperature gradients within the PRT can be sources for
generation of thermoelectric EMF. Some resistance determination error can result from this EMF. The magnitude and sense of this thermoelectric effect
error depends on the excitation current, temperature distribution, and c
...