1、Designation: D 5287 97 (Reapproved 2002)Standard Practice forAutomatic Sampling of Gaseous Fuels1This standard is issued under the fixed designation D 5287; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision.
2、 A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the collection of natural gases andtheir synthetic equivalents using an automatic sampler.1.2 This practice ap
3、plies only to single-phase gas mixturesthat vary in composition. A representative sample cannot beobtained from a two-phase stream.1.3 This practice includes the selection, installation, andmaintenance of automatic sampling systems.1.4 This practice does not include the actual analysis of theacquire
4、d sample. Other applicable ASTM standards, such asTest Method D 1945, should be referenced to acquire thatinformation.1.5 The selection of the sampling system is dependent onseveral interrelated factors. These factors include source dy-namics, operating conditions, cleanliness of the source gases,po
5、tential presence of moisture and hydrocarbon liquids, andtrace hazardous components. For clean, dry gas sources, steadysource dynamics, and normal operating conditions, the systemcan be very simple. As the source dynamics become morecomplex and the potential for liquids increases, or tracehazardous
6、components become present, the complexity of thesystem selected and its controlling logic must be increased.Similarly, installation, operation, and maintenance proceduresmust take these dynamics into account.1.6 The values stated in inch-pound units are to be regardedas the standard. The values give
7、n in parentheses are forinformation only.1.7 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
8、 limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1945 Test Method for Analysis of Natural Gas by GasChromatography22.2 Other Standards:AGA Report Number 7 Measurement of Gas by TurbineMeters3API 14.3 Part 2 (AGA Report Number 3)4GPA Standard 2166 Methods of Obtaining Natural Gas
9、Samples for Analysis by Gas Chromatography5NACE Standard MR-01-75 Standard Material Require-ments. Sulfide Stress Cracking Resistant-Metallic Materi-als for Oilfield Equipment62.3 Federal Documents:Code of Federal Regulations, Title 49, 173, 34(e), p. 38973. Terminology3.1 Definitions of Terms Speci
10、fic to This Standard:3.1.1 automatic sampler(see Fig. 1(a) and (b) a mechani-cal system, composed of a sample probe, sample loop, sampleextractor, sample vessel, and the necessary logic circuits tocontrol the system throughout a period of time, the purpose ofwhich is to compile representative sample
11、s in such a way thatthe final collection is representative of the composition of thegas stream.3.1.2 representative samplea volume of gas that has beenobtained in such a way that the composition of this volume isthe same as the composition of the gas stream from which itwas taken.3.1.3 retrograde co
12、ndensationthe formation of liquidphase by pressure drop at constant temperature on a dew-pointgas stream.83.1.4 sample extractora device to remove the samplefrom the sample loop and put it into the sample vessel.3.1.5 sample loopthe valve, tubing, or manifold(s), orcombination thereof, used for cond
13、ucting the gas stream fromthe probe to the sampling device and back to the source pipe(or atmosphere).1This practice is under the jurisdiction of ASTM Committee D03 on GaseousFuels and is the direct responsibility of Subcommittee D03.01 on Collection andMeasurement of Gaseous Samples.Current edition
14、 approved Nov. 10, 2002. Published May 2003. Originallyapproved in 1992. Last previous edition approved in 2002 as D 5287 97 (2002).2Annual Book of ASTM Standards, Vol 05.06.3Available from American Gas Association, 400 N. Capitol St. N.W., Washing-ton, DC 20001.4Available from the American National
15、 Standards Institute, 25 W. 43rd St., 4thFloor, New York, NY 10036.5Available from Gas Processors Assn, 6526 E. 60th St., Tulsa, OK 74145.6Available from National Association of Corrosion Engineers, 1440 South CreekDr., Houston, TX 77084.7Available from Superintendent of Documents, Government Printi
16、ng Office,Washington, DC 20402.8Bergman, D. F., Tek, M. R., and Katz, D. L., Retrograde Condensation inNatural Gas Pipelines, American Gas Association, Arlington, VA, 1975.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3.1.6 sample
17、probethat portion of the sample loop at-tached to and extending into the pipe containing the gas to besampled.3.1.7 sample vesselthe container in which the sample iscollected, stored, and transported to the analytical equipment.3.1.8 source dynamicschanges in gas supplies, operatingpressures, temper
18、atures, flow rate, and other factors that mayaffect composition or state, or both.4. Significance and Use4.1 This practice should be used when and where a repre-sentative sample is required. A representative sample is neces-sary for accurate billing in custody transfer transactions.4.2 This practice
19、 is not intended to preempt existing con-tract agreements.4.3 Principles pertinent to this practice may be applied inmost contractual agreements.5. Material Selection5.1 The sampling system should be constructed of materialsthat will not corrode as a result of ambient conditions.5.2 The selected mat
20、erial should be inert to all expectedcomponents of the gas stream.5.3 If sour gas (gas that contains hydrogen sulfide andcarbon dioxide) is suspected, NACE standard MR-01-75should be adhered to.6. Sample Probe (see Fig. 2 and Fig. 3)6.1 The sample probe should be mounted vertically in ahorizontal ru
21、n.6.2 The sample probe should penetrate into the center onethird of the pipeline.6.3 The sample probe should not be located within thedefined meter-tube region. (See API 14.3, Part 2, Paragraph2.5.1).6.4 The sample probe should be constructed of stainlesssteel.FIG. 1 Continuous Composite SamplersFIG
22、. 2 Acceptable Probe Types and InstallationsD 5287 97 (2002)26.5 The sample probe should be a minimum of five pipediameters from any device that could cause aerosols orsignificant pressure drop.7. Sample Loop (see Fig. 4)7.1 All valves should be straight bore, full opening, stainlesssteel valves.7.2
23、 The sample loop should be14-in. (6.25-mm) or lessoutside diameter stainless steel tubing.7.3 The supply line shall slope from the probe up to thesampler. All traps caused by low points shall be avoided.7.4 The return line should slope down from the sampler toa connection of lower pressure on the pi
24、peline.7.5 The supply line should be as short as possible, with aminimum number of bends.7.6 The sample loop should be insulated or heat traced, orboth, if ambient temperature conditions could cause conden-sation of the gas flowing through the loop.7.7 Filters or strainers that could cause the sampl
25、e to bebiased are not allowed in the sample loop.7.8 Flow through the sample loop should be verified.8. Automatic Sampler (see Fig. 1(a) and (b)8.1 InstallationThe sampler shall be mounted higher thanthe sample probe. It should be as close to the sample probe asconditions allow. Manufacturers specif
26、ic instructions shouldbe referenced.8.2 MaintenanceThe sampler should be designed for easyfield maintenance. A preventative maintenance schedule asoutlined by the manufacturer should be followed.8.3 VerificationThe sampling personnel should be able toverify that the sample vessel was filled as plann
27、ed. This can beaccomplished by several methods.8.3.1 Chart Recorder(see Fig. 5) This should be con-FIG. 3 Probe LocationsFIG. 4 Schematics of Acceptable Sample Loops FIG. 5 Chart RecorderD 5287 97 (2002)3nected to the sample vessel to indicate and record the increasein pressure as the sample extract
28、or adds increments to thesample vessel. This only applies to the fixed volume vessels.8.3.2 Verification of Sample Extractors OutputNumerousdevices are available to check the output of the sample pump.The devices output may be a contact closure,a4to20mAsignal, a power pulse, or any other type that c
29、an be recorded.This applies to all vessel types.8.3.3 Pressure TransducerLike the chart recorder, thepressure transducer measures the increasing pressure within thefixed volume vessel.8.3.4 Calculation MethodWhen a free-floating piston-type vessel is properly installed with full pipeline pressure on
30、the precharge side, the only way product can move the pistonis by way of the sample extractor. If the frequency anddisplacement are known, the pistons position is verification ofproper fill (calculated flow from the sample extractor shouldequal shown displacement in the free-floating piston vessel).
31、Compensate for changes in pipeline pressure.8.4 Control Methods(see Fig. 1(a) and (b) Two methodsof controlling samplers are currently recognized:8.4.1 Proportional-to-Flow ControlThis method pacesthe sampler with respect to flow. The controller shall becapable of tracking the pipelines flow rate ac
32、curately. Thismethod should be used when the variance of flow rates issignificant or when flow ceases periodically.8.4.2 Time-Based ControlThis method paces the samplewith respect to time only. Take care to avoid sampling from astagnant source. The use of differential pressure switches andother simi
33、lar devices may be used to stop the sampling process.9. Sample Vessels9.1 TypesThere are currently two recognized types, bothof which are in the shape of a cylinder:9.1.1 Variable VolumeConstant Pressure (see Fig.1(a)These cylinders are commonly manufactured as free-floating piston configurations. P
34、ipeline pressure communicateswith one side of this piston. The sampler communicates withthe other side. The sampler pumps the gas into the product sideof the vessel and moves the piston, thus displacing theprecharge gas back into the pipeline. The sample gas stays at ornear pipeline pressure during
35、the entire sample period.9.1.2 Constant VolumeVariable Pressure (see Fig.1(b)These cylinders are commonly referred to as spunbottom single-cavity vessels. Impact extrusion vessels also fitwithin this category. A connection on each end should beprovided to allow for proper purge procedures. The press
36、uregradually builds as the sampler puts the gas into the samplevessel.9.2 Vessel SelectionSeveral factors shall be considered inselecting a vessel, including phase changes, pressure, andvolumes required by various test methods.9.2.1 The variable-volume vessel and volumes required toobtain a represen
37、tative composite sample should be used whenthe phase envelope indicates the possibility of retrogradecondensation.89.2.2 The constant-volume vessel may be used when con-densation is not a consideration.9.2.3 One atmosphere (98 kPa) of sample gas is normally inthe sample vessel at the start of the sa
38、mpling cycle. To reducethe impact of that initial volume, at least ten additionalvolumes should be collected in the sample period. If thecomposition of the initial volume is known and can bemathematically extracted from the sample analysis, this wouldnot apply.9.3 Vessel InstallationAll vessels shou
39、ld be installed in amanner that will minimize dead space between the sampleextractor and the vessel.9.3.1 Variable-volume vessels should be connected so thatthe precharge side communicates with line pressure and can bedisplaced without contaminating the sample. The product sideshould be connected wi
40、th minimum dead volume (see Fig.1(a). Purge the sample lines with sample gas after connectionof the variable-volume vessel.9.3.2 Constant-volume vessels (see Fig. 1(b) should be inthe vertical position when purging. After connecting theconstant-volume vessel to the sampling device, the systemshall b
41、e adequately purged with sample gas to displace any gasin the system. (See GPA Standard 2166 for further explanationof these techniques.)9.3.3 Constant-volume vessels shall be insulated if theambient temperature can affect the sample fill rate. Failure todo this will render the sample useless.9.3.4
42、Only one sample vessel at a time is allowed to beconnected to the sample extractor.9.4 CleaningAll vessels should be free of contaminantsfrom previous samples before they are reinstalled on thesampler. If, however, the remaining contents are known and areaccounted for, they are not considered contam
43、inants.9.4.1 Cleaning SolventsA solvent should be chosen thatwill meet the following requirements:9.4.1.1 Dissolves all constituents of the gas stream,9.4.1.2 Has a low enough boiling point to vaporize, leavingno measurable residue (measurable by the means used toanalyze the natural gas sample),9.4.
44、1.3 Does not react with the seals found in the valves orfree-floating piston vessels, and9.4.1.4 Gives a characteristic chromatographic peak thatdoes not interfere with the hydrocarbon peaks of interest.9.4.2 Cleaning MethodsThe list below of methods are forreference only. There are many other accep
45、table methods.9.4.2.1 Method for Fixed-Volume Vessels:(1) Evacuate the sample gas.(2) Connect the sample cylinder to a solvent source and asolvent return.(3) Open all valves.(4) Fill the cylinder from bottom to top with solvent.(5) Flush solvent through the cylinder for a minimum of 3min (longer if
46、needed).(6) Drain the cylinder.(7) Purge the cylinder with dry, inert gas, or natural gas.(8) Close the valves.(9) Remove the cylinder from the manifold. Label and storeas needed.D 5287 97 (2002)49.4.2.2 Alternative Method for Fixed-Volume VesselsThemethod outlined in 9.4.2.1 can be used with the ex
47、ception ofsteam being substituted for the solvent. The steam should bepushed by an inert gas such as nitrogen.9.4.2.3 Method for Free-Floating Piston VesselsThe fol-lowing conditions should be met:(1) The solvent source should be pressurized to 8 to 10 psig(55 to 69 kPa).(2) The solvent source shoul
48、d be plumbed to allow bidirec-tional flow.(3) This source should be connected to the valve on theproduct side of the free-floating piston vessel.(4) An inert gas source should be available at a pressure ofapproximately 15 to 20 psig (103 to 138 kPa).(5) The inert gas source should be plumbed as to a
49、llowbidirectional flow.(6) The inert gas supply is to be connected to the prechargeside of the vessel.(7) The inert pressure switching valve is to be toggled toallow the piston to evacuate the cylinder and then allow thevessel to fill with solvent.(8) Purge the vessel and fill with solvent at least three times.(9) Purge the vessel with an inert gas source, seal, and store.9.5 Lubrication of Free-Floating Piston VesselsThe lubri-cant on the floating piston moving parts should be as light aspossible. No components of the gas to be sampled c
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