ASTM E834-04
(Practice)Standard Practice for Determining Vacuum Chamber Gaseous Environment Using a Cold Finger
Standard Practice for Determining Vacuum Chamber Gaseous Environment Using a Cold Finger
SIGNIFICANCE AND USE
When applied in the case in which there is no test item in the vacuum chamber (such as during bake-out operations), this procedure may be used to evaluate the performance of the vacuum chamber in relation to other data from the same or other chambers given that critical parameters (for example, length of exposure, temperature of the chamber and cold finger, anisotropy, and so forth) can be related.
The procedure can be used to evaluate the effects of materials found in the residue on items placed in the vacuum chamber.
The procedure can be used to describe the effect of a prior test on the residual gases within a vacuum chamber.
By selecting the time at which the coolant is introduced into the cold finger, the environment present during a selected portion of a test can be characterized. This can be used to determine the relative efficacy of certain vacuum chamber procedures such as bake-out.
The procedure may be used to define the outgassed products of a test item that condense on the cold finger.
The procedure may be used in defining the relative cleanliness of a vacuum chamber.
In applying the results of the procedure to the vacuum chamber in general, consideration must be given to the anisotropy of the molecular fluxes within the chamber.
The procedure is sensitive to both the partial pressures of the gases that form the condensibles and the time of exposure of the cold finger at coolant temperatures.
The procedure is sensitive to any losses of sample that may occur during the various transfer operations and during that procedure wherein the solvent is evaporated by heating it on a steam bath.
Note 1—Reactions between solvent and condensate can occur and would affect the analysis.
SCOPE
1.1 This practice covers a technique for collecting samples of materials that are part of the residual gas environment of an evacuated vacuum chamber. The practice uses a device designated as a "cold finger" that is placed within the environment to be sampled and is cooled so that constituents of the environment are retained on the cold-finger surface.
1.2 The practice covers a method for obtaining a sample from the cold finger and determining the weight of the material removed from the cold finger.
1.3 The practice contains recommendations as to ways in which the sample may be analyzed to identify the constituents that comprise the sample.
1.4 By determining the species that constitute the sample, the practice may be used to assist in defining the source of the constituents and whether the sample is generally representative of samples similarly obtained from the vacuum chamber itself.
1.5 This practice covers alternative approaches and usages to which the practice can be put.
1.6 The degree of molecular flux anisotropy significantly affects the assurance with which one can attribute characteristics determined by this procedure to the vacuum chamber environment in general.
1.7 The temperature of the cold finger significantly affects the quantity and species of materials collected.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. For specific warning statements, see Section .
General Information
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Standards Content (Sample)
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Designation:E834–04
Standard Practice for
Determining Vacuum Chamber Gaseous Environment Using
1
a Cold Finger
This standard is issued under the fixed designation E834; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
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1.1 This practice covers a technique for collecting samples 2.1 ASTM Standards:
of materials that are part of the residual gas environment of an E177 Practice for Use of the Terms Precision and Bias in
evacuated vacuum chamber. The practice uses a device desig- ASTM Test Methods
nated as a “cold finger” that is placed within the environment
3. Terminology
to be sampled and is cooled so that constituents of the
3.1 pretest cold finger sample residue mass, M—the mass
environment are retained on the cold-finger surface.
i
1.2 The practice covers a method for obtaining a sample of material collected from the cold finger during the pretest
operation and as measured by the techniques specified in
fromthecoldfingeranddeterminingtheweightofthematerial
removed from the cold finger. Section 9. The mass is based on a sample volume of 50 mL.
3.2 posttest stock sample residue mass, M—the mass of
1.3 The practice contains recommendations as to ways in
f
which the sample may be analyzed to identify the constituents residue in a sample collected from the cold finger during the
posttest operation and as measured by the technique specified
that comprise the sample.
1.4 By determining the species that constitute the sample, in Section 9.The mass is based on a sample volume of 50 mL.
3.3 pretest stock sample residue mass, S—the mass of
the practice may be used to assist in defining the source of the
i
constituentsandwhetherthesampleisgenerallyrepresentative residue in a sample of the solvent (used to obtain the pretest
cold finger sample) as measured by the technique specified in
of samples similarly obtained from the vacuum chamber itself.
1.5 This practice covers alternative approaches and usages Section 9. The mass is based on a sample volume of 50 mL.
3.4 posttest stock sample residue mass, S—the mass of
to which the practice can be put.
f
residue in a sample of the solvent (used to obtain the posttest
1.6 The degree of molecular flux anisotropy significantly
affects the assurance with which one can attribute characteris- cold finger sample) as measured by the technique specified in
Section 9. The mass is based on a sample volume of 50 mL.
tics determined by this procedure to the vacuum chamber
environment in general. 3.5 cold finger—the device that is used in collecting the
sample of the residual gases in an evacuated vacuum chamber
1.7 The temperature of the cold finger significantly affects
the quantity and species of materials collected. (see Fig. 1).
3.6 CFR—theresiduecollectedbythecoldfingerduringthe
1.8 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the vacuum exposure given in milligrams.
responsibility of the user of this standard to establish appro-
4. Summary of Practice
priate safety and health practices and determine the applica-
4.1 The cold-finger technique provides a method for char-
bility of regulatory limitations prior to use. For specific
acterizing the ambiance in a vacuum chamber when the
warning statements, see Section 8.
chamber is being operated with or without a test item.
4.2 In use, the cold finger is installed in the vacuum
chamber in such a location as to be exposed to fluxes
representative of those in the general ambiance. (Chamber
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This practice is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of SpaceTechnology and is the direct responsibility of
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Subcommittee E21.05 on Contamination. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Sept. 1, 2004. Published September 2004. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1981. Last previous edition approved in 1998 as E834–81 (1998). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/E0834-04. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
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E834–04
differences of mass between the pretest residue and posttest
residue is then determined (corrected if necessary for any
significantresiduefoundinthesolvent);thisdifferenceinmass
is taken as the residue collected by the cold finger during its
exposure to the vacuum environment, CFR.
4.7 Analy
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