1、Designation:D488820Standard Test Method forWater Vapor in Natural Gas Using Length-of-Stain DetectorTubes1This standard is issued under the fixed designation D4888;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revi
2、sion.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 test method covers a procedure for rapid andsimple field determination of water vapor in natural gaspipelines.Available detecto
3、r tubes provide a total measuringrange of 0.1 to 40 mg/L,although the majority of applicationswill be on the lower end of this range(that is,under 0.5 mg/L).At least one manufacturer provides tubes that read directly inpounds of water per million cubic feet of gas.See Note 1.1.2 Detector tubes are u
4、sually subject to interferences fromgases and vapors other than the target substance.Such inter-ferences may vary among brands because of the use of differentdetection methods.Consult manufacturers instructions forspecific interference information.Alcohols and glycols willcause interferences on some
5、 water vapor tubes because of thepresence of the hydroxyl group on those molecules.1.3 UnitsThe values stated in SI units are to be regardedas the standard.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 th
6、is standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decis
7、ion on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D4150 Terminology Relating to Gaseous Fuels3.Terminology3.1 DefinitionsFor definitions
8、 of general terms used inD03 Gaseous Fuels standards,refer to Terminology D4150.4.Summary of Test Method4.1 The sample is passed through a detector tube filled witha specially prepared chemical.Any water vapor present in thesample reacts with the chemical to produce a color change orstain.The length
9、 of the stain produced in the detector tube,when exposed to a measured volume of sample,is directlyproportional to the amount of water vapor present in thesample.A hand-operated piston or bellows-type pump is usedto draw a measured volume of sample through the tube at acontrolled rate of flow.The le
10、ngth of stain produced isconverted to milligrams per liter of H2O by comparison to acalibration scale supplied by the manufacturer for each box ofdetection tubes.The system is direct reading,easily portable,and completely suited to making rapid spot checks for watervapor under field conditions.NOTE1
11、Detector tubes are available with calibration scales printed inpounds of water per million cubic feet of gas(lb/MMCF).The conversionfactor is 1 mg/L=62.3 lb/MMCF(7 lb/MMCF=0.11 mg L).5.Significance and Use5.1 The measurement of water vapor in natural gas isimportant because of the gas quality specif
12、ications,the corro-sive nature of water vapor on pipeline materials,and the effectsof water vapor on utilization equipment.5.2 This test method provides inexpensive field screening ofwater vapor.The system design is such that it may be used bynontechnical personnel with a minimum of proper training.
13、6.Apparatus6.1 Length-of-Stain Detector TubesA sealed glass tubewith the breakoff tips sized to fit the tube holder of the pump.The reagent layer inside the tube,typically a silica gel substratecoated with the active chemical,must be specific for watervapor and produce a distinct color change when e
14、xposed to asample of gas containing water vapor.Any substances knownto interfere must be listed in the instructions accompanying thetubes.A calibration scale should be marked directly on the1This test method is under the jurisdiction ofASTM Committee D03 on GaseousFuels and is the direct responsibil
15、ity of Subcommittee D03.07 on Analysis ofChemical Composition of Gaseous Fuels.Current edition approved Dec.15,2020.Published January 2021.Originallyapproved in 1988.Last previous edition approved in 2015 as D4888 06(2015).DOI:10.1520/D4888-20.2For referenced ASTM standards,visit the ASTM website,ww
16、w.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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides a
