1、Designation: F1398 93 (Reapproved 2012)Standard Test Method forDetermination of Total Hydrocarbon Contribution by GasDistribution System Components1This standard is issued under the fixed designation F1398; the number immediately following the designation indicates the year oforiginal adoption or, i
2、n 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.INTRODUCTIONSemiconductor clean rooms are serviced by high-purity gas distribution systems. Th
3、is test methodpresents a procedure that may be applied for the evaluation of one or more components considered foruse in such systems.1. Scope1.1 This test method covers the testing of components fortotal hydrocarbons (THC) contribution to a gas distributionsystem at ambient temperature. In addition
4、, this test methodallows testing of the component at elevated ambient tempera-tures as high as 70C.1.2 This test method applies to in-line components contain-ing electronics grade materials in the gaseous form, such asthose used in semiconductor gas distribution systems.1.3 Limitations:1.3.1 This te
5、st method is limited by the sensitivity of currentinstrumentation, as well as by the response time of theinstrumentation. This test method is not intended to be used forcomponents larger than 12.7-mm (12-in.) outside diameternominal size. This test method could be applied to largercomponents; howeve
6、r, the stated volumetric flow rate may notprovide adequate mixing to ensure a representative sample.Higher flow rates may improve the mixing but excessivelydilute the sample.1.3.2 Different instrumental methods (such as flame ioniza-tion detector (FID), mass spectrometer (MS) will yield totalhydroca
7、rbon (THC) levels that are not comparable due todifferent sensitivities to different molecular species. Hydrocar-bon contaminants of high-purity gas distribution systems canbe subdivided into two general categories: (1) noncondensablehydrocarbons (C4), that are present due to difficulty ofremoval an
8、d relative atmospheric abundance, and (2) condens-able hydrocarbons, that are often left behind on componentsurfaces as residues. Condensable hydrocarbons include pumpoils, degreasing agents, and polishing compound vehicles.1.3.3 Because of the tremendous disparity of hydrocarbonspecies, it is sugge
9、sted that direct comparisons be made onlyamong data gathered using the same detection method.1.3.4 This test method is intended for use by operators whounderstand the use of the apparatus at a level equivalent to sixmonths of experience.1.4 The values stated in SI units are to be regarded as thestan
10、dard. The inch-pound units given in parentheses are forinformation only.1.5 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 t
11、he applica-bility of regulatory limitations prior to use. Specific hazardstatements are given in Section 5.2. Terminology2.1 Definitions:2.1.1 baselinethe instrument response under steady stateconditions.2.1.2 glove bagan enclosure that contains a controlledatmosphere. A glove box could also be used
12、 for this testmethod.2.1.3 heat trace heating of component, spool piece, or teststand by a uniform and complete wrapping of the item withresistant heat tape.2.1.4 methane (CH4) equivalentthat concentration of CH4that causes the same instrument response as the sample.2.1.4.1 DiscussionThe calibration
13、 gas contains a knownconcentration of methane (CH4). Instrument response to zerogas and span gas defines the calibration curve for the analyzer.Instrument response to the sample is the summation of theresponse for each hydrocarbon reaching the detector. Theconcentration reported is the methane conce
14、ntration, from thecalibration curve that corresponds to the instrument response to1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.10 on Contamina-tion Control.Current edition approved July 1, 2012. Published August
15、2012. Originallyapproved in 1992. Last previous edition approved in 2005 as F1398 93(2005).DOI: 10.1520/F1398-93R12.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1the sample. The samples concentration is equivalent to themethane conc
16、entration that would produce the same instrumentresponse.2.1.5 minimum detection limit (MDL) of the instrumentthelowest instrument response above zero detectable that isreadable by the instrument and at least two times the amplitudeof the noise.2.1.6 response timethe time required for the system tor
17、each steady state after a measurable change in concentration.2.1.7 spool piecea null component, consisting of a straightpiece of electropolished tubing and appropriate fittings, used inplace of the test component to establish the baseline.2.1.8 standard conditions101.3 kPa, 0.0C (14.73 psia,32F).2.1
18、.9 test componentany device being tested, such as avalve, regulator, or filter.2.1.10 test standthe physical test system used to measureimpurity levels.2.1.11 zero gasa gas that has a THC concentration belowthe MDL of the analytical instrument. This purified gas is usedfor both instrument calibratio
19、n and component testing.2.2 Abbreviations:2.2.1 FIDflame ionization detector.2.2.2 MFCmass flow controller.2.2.3 MSmass spectrometer.2.2.4 ppbvparts per billion by volume assuming ideal gasbehavior, equivalent to nmole/mole (such as nL/L).2.2.4.1 DiscussionThe same as molar parts per billion(ppb).2.
20、2.5 ppbwparts per billion by weight (such as ng/g).2.2.6 ppmvparts per million by volume assuming idealgas behavior, equivalent to mole/mole (such as L/L).2.2.6.1 DiscussionThe same as molar parts per million(ppm).2.2.7 ppmwparts per million by weight (such as g/g).2.2.8 slpmstandard liters per minu
21、te. The gas volumetricflow rate measured in liters per minute at 0.0C (32F) and101.3 kPa (1 atm).2.2.9 THCtotal hydrocarbon.2.3 Symbols:2.3.1 P1the inlet pressure measured upstream of thepurifier and filter in the test apparatus.2.3.2 P2the outlet measured downstream of the analyzerin the test appar
22、atus.2.3.3 Q1= the bypass sample flow not going through theanalytical system.2.3.4 Q2= the total sample flow through the analyticalsystem.2.3.5 Qs= the flow through the spool piece or component.2.3.6 Ta= the temperature of the air discharged by theanalyzers cooling exhaust.2.3.7 Ts= the temperature
23、of the spool piece or component.2.3.7.1 DiscussionThe thermocouple must be located incontact with the outside wall of the component or spool piece.2.3.8 V-1, V-2 = inlet and outlet valves of bypass loop,respectively.2.3.9 V-3, V-4 = inlet and outlet valves of test loop, respec-tively.3. Significance
24、 and Use3.1 The purpose of this test method is to define a procedurefor testing components being considered for installation into ahigh-purity gas distribution system. Application of this testmethod is expected to yield comparable data among compo-nents tested for purposes of qualification for this
25、installation.4. Apparatus4.1 Materials:4.1.1 Test Gas, purified nitrogen or argon with a maximumTHC concentration not exceeding the manufacturers statedminimum detection limit of the instrument (MDL). Particulatefiltration of the test gas to 0.02 m or finer is required, using atypical electronics gr
26、ade filter. The filter must be compatiblewith the 94C (200F) bake-out.4.1.2 Spool Piece, that can be installed in place of the testcomponent is required. This piece is to be a straight section of316L electropolished stainless steel tubing with no restrictions.The length of the spool piece shall be 2
27、00 mm. The spool pieceshall have the same end connections as the test component.4.1.2.1 Components with Stub EndsUse compression fit-tings with nylon or teflon ferrules to connect the spool pieceand test component to the test loop. Keep the purged glove bagaround each component for the duration of t
28、he test. In the caseof long pieces of electropolished tubing, use two glove bags,one at each end.4.1.3 Tubing, used downstream of the purifier shall be 316Lelectropolished stainless steel seamless tubing. The diameter ofthe sample line to the analyzer shall not be larger than 6.4 mm(14 in.). The len
29、gth of the sample line from the tee (installedupstream of the pressure gage P2) to the analyzer shall not bemore than 600 mm to minimize the effect (adsorption/desorption) of the sample line on the result. The sample lineshall have no more than two mechanical joints.4.1.4 Valves, diaphragm or bellow
30、s type and must be ca-pable of unimpaired operation at 94C (200F). The use ofall-welded, all-metal valves is preferred.4.2 Instrumentation:4.2.1 THC AnalyzerThe THC analyzer is to be placeddownstream of the test component. Accurate baseline readingsmust be obtained prior to and subsequent to each of
31、 the tests.The baseline must return to levels 100 ppbv, before and afterthe tests. Deviations greater than this require that all results berejected and a new test component be tested. The analyzer mustbe capable of accurately recording changes in THC concentra-tions on a real-time basis, within the
32、constraints of the dataacquisition system.4.2.2 THC analyzer calibrationTwo-point calibration,zero and span, is to be performed regularly. Zero gas is definedas below the manufacturers stated MDL of the instrument,supplied by purified gas, with the purifier in close proximity tothe analyzer. Span ga
33、s is analyzed at the lowest possibledetection range, which may not be at the lowest detection rangeF1398 93 (2012)2of the instrument. Span gas is 510 ppmv methane, 6 20 % forFID. Calibration is based on traceable methane concentrationin the base gas (nitrogen or argon).4.2.3 Flame Ionization Detecto
34、r (FID)The FID detectshydrocarbon species by ionizing the organic material in aflame. Ions produced in the hydrogen flame yield a measurablecurrent, directly related to the quantity of hydrocarbons intro-duced to the flame. Burner gases, hydrogen, and air are not tocontain measurable amounts of THC.
35、 Purifiers are available forthis purpose (especially to remove methane). Burner gasesmust be maintained at a temperature between 18 and 26C (64and 78F).4.2.3.1 The THC data are referred to as ppmv quantity ofCH4equivalents, corresponding to the sum of the number ofequivalent carbons. Simple, low mol
36、ecular weight hydrocar-bons are readily detected and quantified as total THC. Highermolecular weight hydrocarbons and more substituted hydro-carbons may not be detected well. The FID is, therefore, aspecific group detector that yields quantification of totalhydrocarbons for a specific detectable gro
37、up.4.3 Pressure and Flow ControlUpstream pressure is to becontrolled with a regulator upstream of the test component.Flow is to be controlled at a point downstream of the samplingport and monitored at that point. A mass flow controller ispreferred for maintaining the flow as described in 8.3.However
38、, a variable area flowmeter plus a back pressureregulator may be used instead. Sampling is to be performed viaa tee in the line, with a run of straight tubing before the massflow controller. All lines must conform to 4.1.3. Inlet pressureis monitored by P1. Test flow is the sum of Q1and Q2. Q1isdire
39、ctly controlled, and Q2is the total flow through theanalyzer (refer to Fig. 1).4.4 Bypass LoopThe design of the bypass loop is notrestricted to any one design. It could be, for example, a 3.2-mm(18-in.) 316L stainless steel coil or a flexible tube section. Thisallows the flexibility necessary to ins
40、tall test components ofdifferent lengths.5. Hazards5.1 Precautions:5.1.1 It is required that the user have a working knowledgeof the respective instrumentation and that the user practiceproper handling of test components for trace organic analysis.Good laboratory practices must also be understood.5.
41、1.2 It is required that the user be familiar with propercomponent installation and that the test components be in-stalled on the test stand in accordance with manufacturersinstructions.5.1.3 Do not exceed ratings (such as pressure, temperature,and flow) of the component.5.1.4 Gloves are to be worn f
42、or all steps.5.1.5 Limit exposure of the instrument and test componentto atmospheric and hydrocarbon contamination before andduring the test.5.1.6 Precautions must be taken to insure that the tempera-ture measured by the thermocouple is as close as possible tothat of the spool piece or the test comp
43、onent. Use appropriateinsulation and conductive shield to achieve as uniform atemperature as possible.5.1.7 Ensure that adequate mixing of the test gas is attained.6. Preparation of Apparatus6.1 A schematic drawing of a recommended test apparatuslocated inside a clean laboratory is shown in Fig. 1.
44、Deviationsfrom this design are acceptable as long as baseline levelsconsistent with 4.2.1 can be maintained. Nitrogen or argon gasis purified to remove water and hydrocarbons. The base gas isthen filtered by an electronics grade, high purity, point of usegas filter (pore size rating #0.02 m) before
45、it is delivered tothe test component.6.2 A bypass loop may be used to divert gas flow throughthe test stand and the analyzer whenever the spool piece or atest component is installed or removed from the test stand. Thisprevents the ambient air from contaminating the test apparatusand the hydrocarbon
46、analyzer; thus, the analyzer baselineremains the same. A glove bag is used to enclose testcomponent lines of the test apparatus during the installationand removal of the spool piece and the test piece.6.3 A total hydrocarbon analyzer capable of detecting hy-drocarbon concentration levels down to 50
47、ppb is connectedto the test stand to sample the gas flowing through the testpiece. The THC analyzer uses hydrogen fuel for the generationof the flame required for the FID in the instrument. The purifiedand filtered base gas from the test stand containing 10 ppbTHC is used as the zero gas source for
48、the analyzer. Since theanalyzer is sensitive to the sample flow rate, the meteringvalves within the analyzer should be adjusted to yield the flowrates required by the specification for an inlet pressure of 30psig. The gas flow rate Qsis set to 1 L/min.6.4 Inlet gas pressure is controlled by a pressu
49、re regulatorand measured immediately upstream of the purified by anelectronic grade pressure gage. Flow measurement is carriedout by a MFC located downstream of the analyzer. Theoutlet pressure of the gas is measured immediately downstreamof the analyzer by another electronic grade pressure gage. TheMFC along with its digital readout should be calibrated beforeuse to control and display the gas flow rate Q1.6.5 The temperature of the spool piece, test specimen,analyzer cell compartment, and the THC concentration mea-sured by th
