ASTM_E_2877_-_12e1.pdf

Designation:E2877121Standard Guide forDigital Contact Thermometers1This standard is issued under the fixed designation E2877;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1NOTEChanges were made editorially in February 2013.1.Scope1.1 This Guide describes general-purpose,digital contactthermometers(hereafter simply called“digital thermometers”)that provide temperature readings in units of degrees Celsius ordegrees Fahrenheit,or both.The different types of temperaturesensors for these thermometers are described,and their relativemerits are discussed.Nine accuracy classes are introduced fordigital thermometerhes;these classes consider the accuracy ofthe sensor/measuring-instrument unit.1.2 The proposed accuracy classes for digital thermometerspertain to the temperature interval of 200 C to 500 C,aninterval of special interest for many applications in thermom-etry.All of the temperature sensor types for the digitalthermometers discussed are able to measure temperature overat least some range within this interval.Some types are alsoable to measure beyond this interval.To qualify for an accuracyclass,the thermometer must measure correctly to within aspecified value(in units of C)over this interval or over thesubinterval in which they are capable of making measure-ments.Those thermometers that can measure temperature inranges beyond this interval generally have larger measurementuncertainty in these ranges.1.3 The digital thermometer sensors discussed are platinumresistance sensors,thermistors,and thermocouples.The rangeof use for these types of sensors is provided.The measurementuncertainty of a sensor is determined by its tolerance class orgrade and whether the sensor has been calibrated.1.4 This Guide provides a number of recommendations forthe manufacture and selection of a digital thermometer.First,itrecommends that the thermometers sensor conform to appli-cable ASTM specifications.Also,it recommends minimumstandards for documentation on the thermometer and informa-tional markings on the probe and measuring instrument.1.5The derived SI units(degrees Celsius)found in thisGuide are to be considered standard.However,thermometersdisplaying degrees Fahrenheit are compliant with this guide aslong as all other guidance is followed.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Some specifichazards statements are given in Section 7 on Hazards.2.Referenced Documents2.1 ASTM Standards:2E230 Specification and Temperature-Electromotive Force(EMF)Tables for Standardized ThermocouplesE344 Terminology Relating to Thermometry and Hydrom-etryE563 Practice for Preparation and Use of an Ice-Point Bathas a Reference TemperatureE608/E608M Specification for Mineral-Insulated,Metal-Sheathed Base Metal ThermocouplesE644 Test Methods for Testing Industrial Resistance Ther-mometersE839 Test Methods for Sheathed Thermocouples andSheathed Thermocouple CableE879 Specification for Thermistor Sensors for General Pur-pose and Laboratory Temperature MeasurementsE1137/E1137M Specification for Industrial Platinum Resis-tance ThermometersE2181/E2181M Specification for Compacted Mineral-Insulated,Metal-Sheathed,Noble Metal Thermocouplesand Thermocouple CableE2593 Guide for Accuracy Verification of Industrial Plati-num Resistance ThermometersE2846 Guide for Thermocouple Verification3.Terminology3.1 Definitions:The definitions given in Terminology E344apply to terms used in this guide.1This guide is under the jurisdiction of ASTM Committee E20 on TemperatureMeasurement and is the direct responsibility of Subcommittee E20.09 on DigitalContact Thermometers.Current edition approved Nov.1,2012.Published December 2012.DOI:10.1520/E2877122For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2 Definitions:3.2.1 accuracy class,nclass of an item that meets certainmetrological requirements intended to keep errors withinspecified limits.3.2.1.1 DiscussionThis document describes accuracyclasses for digital thermometers.3.2.2 calibration uncertainty,nparameter,derived fromthe analysis of a calibration of a measuring instrument,thatcharacterizes the range in which the true calibration result isestimated to lie within a given confidence level.3.2.3 digital contact thermometer,na device that mea-sures te