ASTM_D_5305_-_18e1.pdf

Designation:D5305181Standard Test Method forDetermination of Ethyl Mercaptan in LP-Gas Vapor1This standard is issued under the fixed designation D5305;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.1NOTEEditorially corrected 7.3 in December 2020.1.Scope*1.1 This test method describes a rapid and simple procedureusing length-of-stain tubes for field measurement of ethylmercaptan in the vapor phase of LP-gas systems.Althoughlength-of-stain tubes are available to detect ethyl mercaptanconcentrations in the range of 0.5 to 120 parts per million byvolume,this test method is specifically applicable to systemscontaining 5 ppm by volume or more of ethyl mercaptan inLP-gas vapors.NOTE1A chromatographic technique can be used for more precise,quantitative determination of ethyl mercaptan in LP-gas.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses after SI units areprovided for information only and are not considered standard.1.3 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,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-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.Referenced Documents2.1 NFPA Standard:2NFPA58 Standard for the Storage and Handling of LiquefiedPetroleum Gases3.Terminology3.1 Abbreviations:3.1.1 EMethyl mercaptan3.1.2 LP-Gas,LPGliquefied petroleum gas3.1.3 PTFEpolytetrafluoroethylene3.1.4 TBMt-butyl mercaptan4.Summary of Test Method4.1 Using a manually-operated vacuum pump,a sample ofLP-gas from the vapor space of an LP-gas cylinder,storagetank or other closed containment system is drawn through adetector tube made specifically for detection of ethyl mercap-tan.The length-of-stain(color change)produced in the detectortube when exposed to a measured volume of sample is directlyproportional to the amount of ethyl mercaptan present in thesample being tested.The length-of-stain produced in thedetector tube is converted to concentration,in parts per millionby volume,by comparison with a calibration scale provided bythe manufacturer of the stain tube.5.Significance and Use5.1 LP-gas is colorless and odorless,and not detectable bynormal human senses.To provide an olfactory warning in theevent of a leak,LP-gas intended for domestic or commercialfuel use is intentionally odorized so as to be readily detectablewell below flammable or suffocating concentration levels ofLP-gas in air.(See Appendix X1 for important explanations.)The most common odorant for LP-gas is ethyl mercaptan.Thefield use of this test method will rapidly determine the presenceand concentration of ethyl mercaptan in LP-gas vapor withoutthe necessity for complex laboratory equipment.6.Interferences6.1 Detector tubes can be subject to interferences frommaterials other than the target substance.Methyl mercaptanwill likely interfere with tubes designed to measure ethylmercaptan.Because of different detection chemistry by differ-ent manufacturers,interferences can vary.Consult the manu-facturers instructions for specific interference information andobserve any instructions given.6.2 Propylene(propene)will cause an interfering(gray)discoloration with some tubes designed for ethyl mercaptan.LP-gas from natural gas sources usually does not containpropylene(propene).However,LP-gas produced in refinery1This test method is under the jurisdiction of ASTM Committee D02 onPetroleum Products,Liquid Fuels,and Lubricants and is the direct responsibility ofSubcommittee D02.H0 on Liquefied Petroleum Gas.Current edition approved April 1,2018.Published May 2018.Originallyapproved in 1992.Last previous edition approved in 2012 as D5305 12.DOI:10.1520/D5305-18E01.2Available from National Fire Protection Association(NFPA),1 BatterymarchPark,Quincy,MA 02169-7471,http:/www.nfpa.org.*A Summary of Changes section appears at the end of this standardCopyright 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 and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1operations often does contain propylene(propene).Detectort