ASTM E295-1982(2014) 9482 Standard Test Method for Measured Speed of Oil Diffusion Pumps《测量油扩散泵速度的标准试验方法》.pdf
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1、Designation: E295 82 (Reapproved 2014)Standard Test Method forMeasured Speed of Oil Diffusion Pumps1This standard is issued under the fixed designation E295; 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the mea-sured speed (volumetric flow rate) of oil diffusion pumps.1.2 The values state
3、d in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconversions to SI units that are provided for information onlyand are not considered standard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use.
4、 It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2E297 Test Method for Calibrating Ionization Vacuum GageTubes (Withdrawn 1983)
5、33. Terminology3.1 measured speedthe mass flow rate of gas admittedfrom a flowmeter divided by the resulting increase in equilib-rium static pressure near the inlet of the pump, using theequipment in Fig. 1.4. Summary of Test Method4.1 The pump under test is fitted with a test dome ofspecified desig
6、n (Fig. 1). Gas is admitted to the test dome in aspecified manner at a measured rate, and the resulting changein equilibrium pressure is measured in a specified way.5. Apparatus5.1 Test DomeThe test dome (Fig. 1) may be constructedby any material and by any method acceptable in high-vacuumpractice,
7、and will normally be connected to the pump by themethod provided for in the design of the pump. The insidediameter of the test dome shall be equal to that of the pumpinlet, and its mean height shall be 1.5 times this diameter (Note1). The gas shall be admitted through a tube projecting into thedome
8、and bent upward so that its exit is located on the axis,facing away from the pump inlet port, and at a distance fromthe pump inlet equal to the dome diameter. The opening to thevacuum gage shall be through a tube radially projecting intothe test dome. The tubulation center line shall be above theinl
9、et flange, 1 in. (25 mm) or14 D above the top of the flange,whichever is larger (see Fig. 1).NOTE 1A10 slope of the dome roof is required only if the dome isto be used for back-streaming measurements.5.2 Gage AttachmentThe gage connecting line shall beless than 6 in. (152 mm) long and at least34 in.
10、 (19 mm) ininside diameter; shall contain one right-angle bend upward tothe gage; and shall project18 in. (3.2 mm) into the test dome.If a McLeod gage is used, it shall be attached in a similarmanner, except that the connecting line, including a mercuryvapor trap, need not meet the dimensional restr
11、ictions above.The use of grease, wax, and rubber in assembling the gage linesshould be minimized.5.3 Flow-Measuring Devices:5.3.1 For flows greater than about 5 104torr L/s (that is,about 25 min/atmospheric cm3), and up to approximately 5 torrL/s (that is, about 15 s/100 atmospheric cm3), some type
12、ofconstant-pressure displacement tube with low-vapor pressurefluid shall be used. These tubes should be provided in a seriesof overlapping ranges so that very small through-puts may bemeasured in a reasonably short time and that very largethrough-puts may be measured in a time interval long enoughto
13、 allow precise measurement.5.3.2 Flow rates less than about 5 104torr L/s may bedetermined by a conductance method in which the test gascontained in a reservoir at known pressure is admitted to thetest dome through a known conductance.5.3.3 For flows greater than 5 torr L/s, special types ofconstant
14、-pressure fluid-displacement devices or a series ofvariable-area flowmeters (rotameters) of sufficient overlap toensure precise measurement should be used.5.3.4 The timing in all flow measurements shall be madewith a110-s stop watch or by some equally precise method.1This test method is under the ju
15、risdiction of the ASTM Committee E21 onSpace Simulation and Applications of Space Technology and is the direct respon-sibility of Subcommittee E21.04 on Space Simulation Test Methods.Current edition approved April 1, 2014. Published April 2014. Originallyapproved in 1967. Last previous edition appro
16、ved in 2006 as E295 82 (2006).DOI: 10.1520/E0295-82R14.2For referenced ASTM standards, visit the ASTM website, www.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.3The l
17、ast approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.4 Leak Control ValveThe leak control valve shouldprovide good control of flow and flow changes as reflecte
18、d inequilibrium pressures through the pressure range of interest.6. Test Gas6.1 Air shall normally be used in the measurement of pumpspeeds; and measured speed for air will be considered a basicperformance characteristic of a pump.6.2 The apparatus and method herein described may be usedfor measurin
19、g pumping speeds for gases other than air as maybe required.7. Calibration and Precision of Flow-Measuring Devices7.1 Constant-Pressure Displacement TubesTo cover con-veniently the input range suggested in 5.3, displacement tubesof at least three overlapping ranges should be provided. Thedisplacemen
20、t tubes should be precision burets of glass tubingselected for uniformity of bore and having accurately measuredinside diameters (accuracy 0.25 %, commercially available).The instruments should be designed, calibrated, and used insuch a way as to measure the actual quantity of gas transferredto the
21、test dome in some conveniently measurable time.Ambient temperature during the measurement shall be 23 63C. Meters of the constant-pressure displacement type maytake various forms. Two of these are shown in Fig. X1. anddiscussed in Appendix X2.7.2 Conductance MethodThis method of measuring inputrate
22、requires a conductance of accurately known dimensionsand a reservoir of test gas in which the pressure can be variedand accurately measured (see Fig. X2. and Fig. X3. andAppendix X3). It requires, in addition, that the dimensions ofthe conductance be so chosen as to permit the desired maxi-mum throu
23、gh-put (5 104torr L/s or more) at a reservoirpressure that does not exceed the condition for free molecularflow through any part (that is, the mean free path of gas in thereservoir must be equal to or greater than ten times the largestlinear dimension of the reservoir). Gas introduced into thereserv
24、oir must be directed away from the conductance en-trance.8. Calibration and Precision of Vacuum Gages8.1 To cover the full range of pressures at which pumpspeeds should be measured requires that at least two types ofvacuum gages be used:8.1.1 McLeod GageFor measuring pressures greater than103torr, a
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