1、Designation: D6273 08D6273 14Standard Test Methods forNatural Gas Odor Intensity1This standard is issued under the fixed designation D6273; 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 pare
2、ntheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the procedures for determining the odor intensity of natural gas through the use of instrumentsthat dilute and mix the sampl
3、ed natural gas with air. The mixed gas stream is then sniffed by the operator for the purpose ofdetermining the threshold detection level or the readily detection level, or both, for odorant in the natural gas stream.1.2 This standard does not purport to address all of the safety concerns, if any, a
4、ssociated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D4150 Terminology Relating to Gaseous FuelsD5287 Practice
5、 for Automatic Sampling of Gaseous FuelsE253 Terminology Relating to Sensory Evaluation of Materials and Products2.2 Other Standards49 CFR Part 192.625 Odorization of gas33. Terminology3.1 Definitions:3.1.1 odorant, nsulfur-bearing compound that gives natural gas a distinctive odor. For the purpose
6、of these test methods,natural gas odorants may be compounds that are present at the wellhead or commercial mixtures that are added to the gas stream,or both.3.1.2 olfactory fatigue, ndesensitization of the sense of smell through either prolonged exposure or repeated exposure overa short period of ti
7、me to an odor, a mixture of odors, or series of odors.3.1.3 sniff, vismell or snuff with short, audible inhalations.3.2 Definitions of Terms Specific to This Standard:3.2.1 high pressure, nfor the purpose of these test methods, high pressure refers to natural gas pressure greater than themaximum inl
8、et pressure specified by the manufacturer of the gas dilution apparatus.3.2.2 intensity, nthe magnitude of odor perceived by the operator.3.2.3 low pressure, nfor the purpose of these test methods, low pressure refers to natural gas pressure less than or equal tothe maximum inlet pressure specified
9、by the manufacturer of the gas dilution apparatus.3.2.4 operator(s), nthe person(s) performing the testing described in these test methods. Because of the nature of the testingdescribed herein, the operator shall be qualified to perform this work (see 5.2).3.2.5 readily detectable level, nthe concen
10、tration of natural gas and odorant mixture in air at which the operator is able todetect and identify natural gas odor.1 These test methods are under the jurisdiction of Committee D03 on Gaseous Fuels and is the direct responsibility of Subcommittee D03.05 on Determination of SpecialConstituents of
11、Gaseous Fuels.Current edition approved May 1, 2008Jan. 1, 2014. Published May 2008February 2014. Originally approved in 1998. Last previous edition approved in 20032008 asD6273 98D6273 08.(2003). DOI: 10.1520/D6273-08.10.1520/D6273-14.2 For referencedASTM standards, visit theASTM website, www.astm.o
12、rg, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3 Available from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-50
13、98, http:/www.dodssp.daps.mil.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommend
14、s that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.6 threshold de
15、tection level, nthe concentration of natural gas and odorant mixture in air at which the operator is barelyable to detect an odor.3.3 For definitions of terms related to natural gas that are used in these test methods, refer to Practice D5287.3.4 For definitions of terms related to olfactory testing
16、 that are used in these test methods, refer to Terminology E253.4. Significance and Use4.1 Federal regulations (49 CFR Part 192.625) state: “A combustible gas in a distribution line must contain a natural odorantor be odorized so that at a concentration in air of one-fifth of the lower explosive lim
17、it, the gas is readily detectable by a personwith a normal sense of smell.” These regulations state further that “each operator shall“To assure the proper concentration ofodorant with this section, each operator must conduct periodic sampling of combustible gases to assure the proper concentrationof
18、 odorant in accordance with this section.” using an instrument capable of determining the percentage of gas in air at which theodor becomes readily detectable.”Additionally, a number of states have enacted legislation that requires natural gas to be odorizedso that it is detectable at concentrations
19、 less than one fifth of the lower explosive limit. See note Note 1. While regulations do notspecify the exact method for determining compliance, it has been documented that compliance testing must be olfactory in nature.4NOTE 1For example, Massachusetts Section 192.625 MFS Standards requires that “.
20、 a concentration of fifteen hundredths of one percent gas in theair is readily perceptible to the normal or average olfactory senses of a person . .” person.”4.2 These test methods cover procedures to measure the odor level of natural gas by way of olfactory determination. No directcorrelation may b
21、e ascertained between these test methods and those methods available or under development that quantitativelymeasure the concentration of sulfur compounds in natural gas.4.3 These test methods outline general procedures to measure the odor detection levels of natural gas. It is the responsibilityof
22、persons using these test methods to develop and maintain equipment and specific operating procedures to ensure public safetyand compliance with all appropriate regulations.5. Interferences and Precautions5.1 The location to be tested should be sheltered from wind and isolated from sources of interfe
23、ring odors such as those fromcertain industrial plants and landfills. The equipment and sampling lines used in testing shall be clean and free of odor.5.2 Operators shall be trained to perform odor testing of natural gas and in the proper use and care of test instrumentation. Itis preferred that ope
24、rators should be nonsmokers, or, if smokers, they shall not smoke for at least 30 min before performing thetest. Additionally, operators shall not chew tobacco or gum or eat food of pungent taste or odor for at least 30 min beforeperforming the test. Operators should have no cold, allergies, or othe
25、r physical conditions that would affect their sense of smell.5.3 Prolonged use of the sense of smell may result in olfactory fatigue. Sufficient time shall be allotted between tests to ensurethat the testers sense of smell is not adversely affected by the previous test.6. Apparatus6.1 Gas Dilution A
26、pparatusThis apparatus shall consist of a gas inlet control valve, a gas/air mixing chamber, a sample portfor sniffing the gas/air mixture, and a method to determine the relative concentration of the gas/air mixture. All components thatcome in contact with natural gas shall be inert to odorant compo
27、unds.6.2 Natural Gas Pressure Regulator(s)This item may be required to lower the gas pressure at the sampling location to a levelthat is safe for the gas dilution apparatus as specified by the manufacturer. This regulator may need to be a heated regulator if anextremely large pressure drop is requir
28、ed, for example, when compressed natural gas or gas at transmission line pressure is to betested. More than one regulator may be required to perform this function satisfactorily.6.2.1 The gas dilution apparatus shall never be subjected to natural gas pressures greater than that specified by the manu
29、facturer.Excessive natural gas pressure may result in instrument failure and cause an excessive amount of gas to vent out of the instrument.6.2.2 The regulator shall be a heated regulator when compressed natural gas (CNG) is to be tested or when it is anticipated thatliquid hydrocarbons may condense
30、 from the gas stream as a result of Joule-Thompson Expansion. Odorant compounds have apreference for liquid hydrocarbons when present.6.3 Sample LineThe sample line shall be clean and consist of material that is inert to natural gas odorant compounds. Samplelines shall be tested periodically by perf
31、orming a blank determination as specified in 9.1 and replaced as required. Rubber or coppertubing shall not be used. Appropriate material for sample lines include stainless steel, aluminum, urethane, PTFE, PVC, and PEK.6.4 Sample ProbeA stainless steel sample probe shall be used where appropriate to
32、 prevent the possibility of pipelinecontaminants from entering the sample stream. (See Section 6 of Practice D5287 for specifics on sample probe construction andinstallation.)4 American Gas Association Operating Section Technical Note CAS-2-1-95, “ Natural Gas Odorization: Compliance with Federal Re
33、gulations.”D6273 1427. Hazards7.1 Because these test methods involve the sampling of natural gas and the venting of a gas/air mixture, only qualified personsshall perform the testing described. These test methods shall not be performed near open flames. Failure to follow manufacturersinstructions fo
34、r the instrumentation used in these test methods may result in a hazardous condition.7.2 These test methods shall never be performed at locations that potentially contain sour gas. High concentrations of hydrogensulfide can quickly poison the operator resulting in death or permanent injury.7.3 Cauti
35、on must be exercised in selecting appropriate instrumentation used in application of thisthese test method.methods.Odor intensity instrumentation should be operated and suited for the intended use including suitability to area classification andmeasurement environment.8. Sampling8.1 Location:8.1.1 T
36、he location shall be far enough from an odorizing station to ensure that the odorant is well mixed within the gas stream.8.1.2 In systems fed by more than one odorizer, test points shall be located to ensure that the odorant concentration suppliedby each individual odorizer is evaluated.8.1.3 In lar
37、ge systems, test points also shall be selected at or near the end of the system to ensure adequate odorantconcentration.8.2 Frequency:8.2.1 Sampling frequency shall be established in accordance with applicable regulations and company policy.8.3 Low-Pressure Sampling:8.3.1 In low-pressure sampling, t
38、he gas dilution apparatus is connected directly to the gas source with the appropriate tubingas specified in 6.3. Connections shall be made to the appropriate gas dilution apparatus port in accordance with the manufacturersinstructions.8.4 High-Pressure Sampling:8.4.1 In high-pressure sampling, a re
39、gulator is connected directly to the gas source with the appropriate tubing as specified in6.3.8.4.1.1 In addition to other precautions, the gas pressure should be taken into consideration when selecting the tubing thatconnects the gas source with the inlet of the regulator. Stainless steel shall be
40、 the only material used for this purpose when thesampling source is CNG.8.4.2 If a heated regulator is used, then the temperature shall be set high enough to prevent hydrocarbon condensation.NOTE 2A regulator set temperature of 140F (60C) has been found to be adequate in most circumstances.8.4.3 The
41、 tubing connection between the regulator outlet and the gas dilution apparatus shall be as specified in 8.3.1.9. Calibration and Maintenance9.1 Blank DeterminationThis test should be performed every 30 days with each gas dilution apparatus.9.1.1 The gas dilution apparatus shall not be connected to a
42、 natural gas source.9.1.2 Power on the apparatus and allow air to flow.9.1.3 Sniff at the apparatus exhaust. The nose shall be approximately three fourths of an inch from the exhaust.9.1.4 If an odor is detected, allow the instrument to operate for an additional 2 to 3 min, then repeat 9.1.3. If an
43、odor is stilldetected, return the instrument to the manufacturer for repair.9.2 Other calibration and maintenance of the gas dilution apparatus shall be performed in accordance with the manufacturersinstructions.10. Procedure10.1 These procedures may be performed by two persons. When this occurs, on
44、e person should operate the gas dilutionapparatus operating valves and the other act as the observer.10.2 Odor Concentration Method:10.2.1 Ensure that the gas inlet valve on the gas dilution apparatus is in the closed or “OFF” position.10.2.2 Connect the gas dilution apparatus to the natural gas sup
45、ply source in accordance with Section 8. Open the gas inlet valveto ensure that air is purged from the sample line. Close the gas inlet valve.10.2.3 Turn the gas dilution apparatus power switch to the “ON” position.10.2.4 Sniff at the apparatus exhaust. The nose shall be approximately three fourths
46、of an inch from the exhaust.10.2.5 If an odor is detected, allow the instrument to operate for an additional 2 to 3 min, then repeat 10.2.4. If an odor is stilldetected, perform a blank determination as specified in 9.1.D6273 14310.2.6 Slowly open the gas inlet valve. Periodically sniff the gas/air
47、mixture at the apparatus exhaust. Breathe fresh air throughthe nose between sniffs of the gas-air mixture. Continue until a faint odor is observed. Determine the gas in air concentration inaccordance with manufacturers instructions. This is the threshold detection level.10.2.7 Continue to open the g
48、as inlet valve. Periodically sniff the gas/air mixture at the apparatus exhaust. Continue until areadily detectable odor of gas is observed. Determine the gas in air concentration in accordance with manufacturers instructions.This is the readily detectable level.10.3 Odor Intensity Method:10.3.1 Ens
49、ure that the gas inlet valve on the gas dilution apparatus is in the closed or “OFF” position.10.3.2 Connect the gas dilution apparatus to the natural gas supply source in accordance with Section 8. Open the gas inlet valveto ensure that air is purged from the sample line. Close the gas inlet valve.10.3.3 Turn the gas dilution apparatus power switch to the “ON” position.10.3.4 Sniff at the apparatus exhaust. The nose shall be approximately three fourths of an inch from the exhaust.10.3.5 If an odor is detected, allow the instrument to operate for an a
