ASTM E2877-12
(Guide)Standard Guide for Standard Guide for Digital Contact Thermometers
Standard Guide for Standard Guide for Digital Contact Thermometers
SIGNIFICANCE AND USE
4.1 Digital thermometers are used for measuring temperature in many laboratories and industrial applications.
4.2 For many applications, digital thermometers using external probes are considered environmentally-safe alternatives to mercury-in-glass thermometers. (1)3
4.3 Some digital thermometers are also used as reference or working temperature standards in verification and calibration of thermometers and also in determining the conditions necessary for evaluating the performance of other measuring instruments used in legal metrology and industry.
SCOPE
1.1 This Guide describes general-purpose, digital contact thermometers (hereafter simply called “digital thermometers”) that provide temperature readings in units of degrees Celsius or degrees Fahrenheit, or both. The different types of temperature sensors for these thermometers are described, and their relative merits are discussed. Nine accuracy classes are introduced for digital thermometerhes; these classes consider the accuracy of the sensor/measuring-instrument unit.
1.2 The proposed accuracy classes for digital thermometers pertain to the temperature interval of –200 °C to 500 °C, an interval of special interest for many applications in thermometry. All of the temperature sensor types for the digital thermometers discussed are able to measure temperature over at least some range within this interval. Some types are also able to measure beyond this interval. To qualify for an accuracy class, the thermometer must measure correctly to within a specified value (in units of °C) over this interval or over the subinterval in which they are capable of making measurements. Those thermometers that can measure temperature in ranges beyond this interval generally have larger measurement uncertainty in these ranges.
1.3 The digital thermometer sensors discussed are platinum resistance sensors, thermistors, and thermocouples. The range of use for these types of sensors is provided. The measurement uncertainty of a sensor is determined by its tolerance class or grade and whether the sensor has been calibrated.
1.4 This Guide provides a number of recommendations for the manufacture and selection of a digital thermometer. First, it recommends that the thermometer’s sensor conform to applicable ASTM specifications. Also, it recommends minimum standards for documentation on the thermometer and informational markings on the probe and measuring instrument.
1.5 The derived SI units (degrees Celsius) found in this Guide are to be considered standard. However, thermometers displaying degrees Fahrenheit are compliant with this guide as long as all other guidance is followed.
1.6 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. Some specific hazards statements are given in Section 7 on Hazards.
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Designation: E2877 − 12
StandardGuide for
1
Standard Guide for Digital Contact Thermometers
This standard is issued under the fixed designation E2877; 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 1.6 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
1.1 This Guide describes general-purpose, digital contact
responsibility of the user of this standard to establish appro-
thermometers (hereafter simply called “digital thermometers”)
priate safety and health practices and determine the applica-
thatprovidetemperaturereadingsinunitsofdegreesCelsiusor
bility of regulatory limitations prior to use. Some specific
degrees Fahrenheit, or both.The different types of temperature
hazards statements are given in Section 7 on Hazards.
sensorsforthesethermometersaredescribed,andtheirrelative
merits are discussed. Nine accuracy classes are introduced for
2. Referenced Documents
digital thermometerhes; these classes consider the accuracy of
2
2.1 ASTM Standards:
the sensor/measuring-instrument unit.
E230Specification and Temperature-Electromotive Force
1.2 The proposed accuracy classes for digital thermometers
(EMF) Tables for Standardized Thermocouples
pertain to the temperature interval of –200 °C to 500 °C, an
E344Terminology Relating to Thermometry and Hydrom-
interval of special interest for many applications in thermom-
etry
etry. All of the temperature sensor types for the digital
E563Practice for Preparation and Use of an Ice-Point Bath
thermometers discussed are able to measure temperature over
as a Reference Temperature
at least some range within this interval. Some types are also
E608/E608MSpecification for Mineral-Insulated, Metal-
abletomeasurebeyondthisinterval.Toqualifyforanaccuracy
Sheathed Base Metal Thermocouples
class, the thermometer must measure correctly to within a
E644Test Methods for Testing Industrial Resistance Ther-
specified value (in units of °C) over this interval or over the
mometers
subinterval in which they are capable of making measure-
E839 Test Methods for Sheathed Thermocouples and
ments. Those thermometers that can measure temperature in
Sheathed Thermocouple Cable
ranges beyond this interval generally have larger measurement
E879Specification for Thermistor Sensors for General Pur-
uncertainty in these ranges.
pose and Laboratory Temperature Measurements
1.3 The digital thermometer sensors discussed are platinum
E1137/E1137MSpecification for Industrial Platinum Resis-
resistance sensors, thermistors, and thermocouples. The range tance Thermometers
ofuseforthesetypesofsensorsisprovided.Themeasurement
E2181/E2181M Specification for Compacted Mineral-
uncertainty of a sensor is determined by its tolerance class or Insulated, Metal-Sheathed, Noble Metal Thermocouples
grade and whether the sensor has been calibrated.
and Thermocouple Cable
E2593Guide for Accuracy Verification of Industrial Plati-
1.4 This Guide provides a number of recommendations for
num Resistance Thermometers
themanufactureandselectionofadigitalthermometer.First,it
E2846Guide for Thermocouple Verification
recommends that the thermometer’s sensor conform to appli-
cable ASTM specifications. Also, it recommends minimum
3. Terminology
standards for documentation on the thermometer and informa-
3.1 Definitions: The definitions given in Terminology E344
tional markings on the probe and measuring instrument.
apply to terms used in this guide.
1.5 The derived SI units (degrees Celsius) found in this
3.2 Definitions:
Guide are to be considered standard. However, thermometers
3.2.1 accuracy class, n—class of an item that meets certain
displaying degrees Fahrenheit are compliant with this guide as
metrological requirements intended to keep errors within
long as all other guidance is followed.
specified limits.
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This guide is under the jurisdiction ofASTM Committee E20 on Temperature
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Measurement and is the direct responsibility of Subcommittee E20.09 on Digital For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Contact Thermometers. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Nov. 1, 2012. Published December 2012. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/E2877–12 the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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E2877 − 12
3.2.1.1 Discussion—This document describes accuracy 4. Significance and Use
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