ASTM_D_7962_-_15.pdf

Designation:D796215Standard Practice forDetermination of Minimum Immersion Depth andAssessment of Temperature Sensor Measurement Drift1This standard is issued under the fixed designation D7962;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.1.Scope1.1 This practice describes a two procedures for use withtemperature measurement devices.Methodology is describedfor determining minimum immersion depth for thermalsensors,in particular RTDs or similar temperature sensors.Included is a procedure for consistently preparing a referencebath for the purpose of monitoring measurement drift ofthermal sensors such as liquid-in-glass or digital contactthermometers.1.2 This practice focuses on temperature measurement driftin a laboratory.If the user requires greater measurementaccuracy,then they should follow the instructions in PracticeE563.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 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.2.Referenced Documents2.1 ASTM Standards:2E563 Practice for Preparation and Use of an Ice-Point Bathas a Reference Temperature3.Terminology3.1 Definitions:3.1.1 ice-point bath,nphysical system containing ice andwater assembled to realize the ice point as a referencetemperature,or to establish a constant temperature near 0 C.3.1.2 minimum immersion length,ndepth that a thermom-etershouldbeimmersed,inauniformtemperatureenvironment,such that further immersion does not produce achange in indicated temperature greater than the specifiedtolerance.4.Summary of Practice4.1 This practice describes a procedure for consistentlypreparing an ice bath that is an intimate mixture of crushed iceor ice particles and water in a thermally insulating vessel opento the atmosphere.4.1.1 Cautionwhen the ice bath is not made from distilledwater,its temperature will differ from the natural fixed-pointtemperature by a consistent amount,typically less than0.02 C.If the user needs a more accurate ice point,then theyshould use Practice E563 to prepare the ice bath.4.2 This practice includes a procedure for determining theminimum immersion depth of the temperature sensor using anice bath.4.2.1 This procedure determines minimum immersion depthwith a 25 C differential between sensed temperature andambient temperature.If the probe is subjected to a greaterdifferential temperature,a larger immersion depth may berequired to correctly measure the temperature.5.Significance and Use5.1 This practice provides a means for the users of ASTMCommittee D02 standards to monitor the drift in sensedtemperature of liquid-in-glass thermometer(LiG),and digitalcontact thermometers(DCT).Digital contact thermometers aresometimes referred to as portable electronic thermometers(PET)or simply digital thermometers.5.2 This practice is not suitable for determining the accu-racy or calibration of a temperature measuring device as theerror in the ice bath temperature can be greater than 0.02 C.For greater accuracy,the user should use Practice E563 toprepare the ice bath.5.3 The ice point is a common practical industrial referencepoint of thermometry.The ice point is relatively simple torealize and provides a readily available natural fixed-pointreference temperature.1This practice is under the jurisdiction of ASTM Committee D02 on PetroleumProducts,Liquid Fuels,and Lubricants and is the direct responsibility of Subcom-mittee D02.91 on Coordinating Subcommittee on Thermometry.Current edition approved April 1,2015.Published April 2015.DOI:10.1520/D7962-15.2For 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 5.4 This practice only checks the measurement drift at asingle temperature.It will not detect a change in measurementresponse with change in temperature.Temperature measuringdevices should be recalibrated at set intervals.See devicesupplier for recommendations.5.5 This practice provides a technique to determine mini-mum immersion depth of the sensing probe of the thermometerusing an ice bath.The minimum immersion depth determinedby this practice may change when the differential temperaturediffers significantly from the conditions described.A greaterdifferential will likely increase the minimum immersion depth.6.Reagents