1、Designation:D417882(Reapproved 2017)Standard Practice forCalibrating Moisture Analyzers1This standard is issued under the fixed designation D4178;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 p
2、arentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers a calibration technique based on thepreparation of standards of known water content.This tech-nique is applicable to the producti
3、on of standards between20 cm3/m3and 2000 cm3/m3water.1.2 The values stated in SI units are to be regarded asstandard.1.2.1 ExceptionThe values given in parentheses are forinformation only.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is the
4、responsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-
5、ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Summary of Practice22.1 The practice is based on the principle that ice has avapor pressure of
6、 0.611 kPa at 0 C.Therefore,when a carriergas at a constant gauge pressure of 207 kPa(30 psig)is passedthrough a molecular sieve saturated with water and held at0 C,the total pressure is equal to 207 kPa plus 98 kPa(oneatmosphere)and the water concentration of the gas leaving themolecular sieve is 0
7、.611/(207+98)106ppm or 2000 ppmvolume water,regardless of flow.2.1.1 A carrier gas at a constant gauge pressure of 207 kPais passed through a molecular sieve drier and then routed overa molecular sieve support saturated with water and equilibratedat 0 C.2.1.2 By blending different volumes of the wet
8、 carrier gaswith dried carrier gas,gas standards of known water concen-tration can be prepared.2.2 The moisture analyzer to be calibrated is then connectedto the source of the gas standard of known water concentration.3.Significance and Use3.1 This practice is intended to provide a method to cali-br
9、ate moisture analyzers used on-stream or in the laboratory.4.Apparatus4.1 Ice Bath Primary Standard Moisture ApparatusFig.1illustrates a typical system.4.2 Wet Test Meter,1 L divisions.4.3 Bubble Meter,graduated in cubic centimetres.4.4 Pressure GaugeA Bourdon-type spring gauge of testgauge quality,
10、100 mm to 250 mm in diameter,with a scalerange from 0 kPa to 400 kPa(0 psi to 60 psi),maximumintermediate graduations of 1.5 kPa(0.25 psi).4.5 Wet Mole Sieve 5A,60/80 mesh(other mesh sizes maybe used,except powder).5.Preparation of Apparatus5.1 Saturate mole sieve with water.5.1.1 Cover in beaker en
11、ough mole sieve to fill the wet molesieve container.Add water to cover mole sieve.Let standovernight.5.1.2 Drain the excess water by pouring the mole sieveslurry into a filtering funnel and letting all the free water drainout.NOTE1The useful lifetime of the wet mole sieve is not known.It isrecommend
12、ed that the procedure described in 5.1.1 and 5.1.2 be followedprior to each calibration.6.Procedure6.1 Fill the ice bath bucket for the primary standard appa-ratus one third full of water;then add ice to bring the level tofull.6.2 Close the wet flow and the diluent flow needle values.6.3 Turn on the
13、 carrier gas supply(nitrogen or air)andadjust the regulator to 207 kPa(30 psig).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.D0 on Hydrocarbons for Chemical and Special Uses.Curre
14、nt edition approved Oct.1,2017.Published November 2017.Originallyapproved in 1982.Last previous edition approved in 2012 as D4178 82(2012).DOI:10.1520/D4178-82R17.2For a more complete discussion of this procedure,see Mator,R.T.,“TraceMoisture Analyzers and Their Calibration,”Proceedings of the 20th
15、Annual ISAAnalysis Instrumentation Symposium,May 12-15,1974,Pittsburgh,PA,“Session:Sampling and Calibration Systems,”1974,p.125.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with int
16、ernationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 6.4 Open the diluent flow needle valve to obtain a carriergas flow of 1 Lmin,as measured with a wet test meter.6.5 Allow the apparatus to equilibrate for 1 h.This allowsthe wet mole sieve to equilibrate at 0 C.6.6 After 1 h,attach the moisture anal
