ASTM F91-70(2001)e1
(Practice)Standard Practice for Testing for Leaks in the Filters Associated With Laminar Flow Clean Rooms and Clean Work Stations by Use of a Condensation Nuclei Detector
Standard Practice for Testing for Leaks in the Filters Associated With Laminar Flow Clean Rooms and Clean Work Stations by Use of a Condensation Nuclei Detector
SCOPE
1.1 This practice covers the testing of the integrity of high-efficiency particulate air (HEPA) filters installed in laminar flow clean rooms of the ceiling to floor or wall to wall type, and laminar flow clean work stations. The recommended practice may be used to detect faults or voids in the filter media itself or in the joints between the filter and the room or work station structure. The determination of filter media efficiency is not within the scope of this practice.
1.2 The values stated in inch-pound units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems 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.
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e1
Designation:F91–70 (Reapproved 2001)
Standard Practice for
Testing for Leaks in the Filters Associated With Laminar
Flow Clean Rooms and Clean Work Stations by Use of a
Condensation Nuclei Detector
ThisstandardisissuedunderthefixeddesignationF 91;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Keywords were added editorially July 2001.
1. Scope nuclei found in ordinary room air. In this recommended
practice a nuclei counting apparatus is arranged to sample
1.1 This practice covers the testing of the integrity of
small areas at the filter surface and the joints at the filter edges.
high-efficiency particulate air (HEPA) filters installed in lami-
The HEPA filter effluent normally shows a low nuclei count
nar flow clean rooms of the ceiling to floor or wall to wall type,
(<100particles/cm ).Whenaleakingfilterareaisencountered,
and laminar flow clean work stations. The recommended
an increase of at least ten-fold in the particle count is noticed
practicemaybeusedtodetectfaultsorvoidsinthefiltermedia
within the 2-s response time of the nuclei counter.
itself or in the joints between the filter and the room or work
station structure.The determination of filter media efficiency is
4. Apparatus
not within the scope of this practice.
,
2 3
4.1 Condensation Nuclei Counter .
1.2 The values stated in inch-pound units are to be regarded
3 1
4.2 Plastic Tubing , ⁄8 in. (9.5 mm) in outside diameter; ⁄4
as the standard. The values given in parentheses are for
in. (6.5 mm) in inside diameter; of suitable length, not to
information only.
exceed 5 ft. (1.5 m).
1.3 This standard does not purport to address all of the
4.3 Glass Laboratory Funnel, 50 mm in outside diameter, 7
safety concerns associated with its use. It is the responsibility
mm in stem diameter, 80 mm over-all length.
of the user of this standard to establish appropriate safety and
4.4 Double-Pole Single-Throw Relay, 115 V, 8 A.
health practices and determine the applicability of regulatory
limitations prior to use.
5. Preparation for Test
5.1 Assemble the apparatus by slipping one end of the
2. Terminology
plastic hose over the funnel stem, and the other end over the
2.1 Definitions:
nuclei counter input nipple.
2.1.1 condensation nuclei—particles within the size range
5.2 Turn on the electrical supply to the nuclei counter and
from 0.001 to 0.1-µm radius.
allow 30 min warm up time with the input tube sampling the
2.1.2 HEPA filter—high-efficiency particulate air filter.
effluent from a HEPA filter.
2.1.3 laminar flow—airflowinwhichtheairconfinedwithin
5.3 Measure the nuclei concentration at the intake to the
the walls of a room or a smaller work station moves as an
HEPA filter. A concentration of less than 1000 particles/cm
isovelocity front along parallel flow lines.
indicatesaconcentrationinsufficientforconvenientlydetecting
2.1.4 leak—a gap or void in the filter media, or in the
leaks in the filter or its gaskets.
associated gaskets, which permits unfiltered room air to pen-
5.3.1 In the event that a nuclei concentration of less than
etrate the clean room or clean work station.
1000 particles/cm occurs when sampling a clean work station,
3. Summary of Practice move the work station into a room having a less clean ambient
such as a room not supplied with filtered air.
3.1 This recommended practice takes advantage of the fact
5.3.2 In the event that the intake nuclei concentration of less
that a HEPAfilter retains a high percentage of the condensation
than 1000 particles/cm occurs in a laminar flow room of the
This practice is under the jurisdiction of ASTM Committee E21 on Space
Simulation andApplications of Space Technology and is the direct responsibility of Rich,T.A., “AContinuous Recorder for Condensation Nuclei,” Geofisica Pura
Subcommittee E21.05 on Contamination. e Applicata, Milano, Vol 50 1961 III, pp 46–52.
Current edition approved Oct. 2, 1970. Originally issued 1968. Replaces General Electric Co., Schenectady, NY, Model No. 112L48
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