ASTM F91-06

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:F91–06
Standard Practice for
Testing for Leaks in the Filters Associated With Laminar
Flow Clean Rooms and Clean Work Stations by Use of a
1
Condensation Nuclei Detector
This standard is issued under the fixed designation F91; 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.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope practice a nuclei counting apparatus is arranged to sample
small areas at the filter surface and the joints at the filter edges.
1.1 This practice covers the testing of the integrity of
The HEPA filter effluent normally shows a low nuclei count
high-efficiency particulate air (HEPA) filters installed in lami-
3
(<100particles/cm ).Whenaleakingfilterareaisencountered,
nar flow clean rooms of the ceiling to floor or wall to wall type,
an increase of at least ten-fold in the particle count is noticed
and laminar flow clean work stations. The recommended
within the 2-s response time of the nuclei counter.
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
4. Apparatus
station structure.The determination of filter media efficiency is
,
2 3
4.1 Condensation Nuclei Counter .
not within the scope of this practice.
4
3
4.2 Plastic Tubing , 9.5 mm ( ⁄8 in.) in outside diameter; 6.5
1.2 The values stated in metric units are to be regarded as
1
mm ( ⁄4 in.) in inside diameter; of suitable length, not to exceed
the standard. The values given in parentheses in inch-pound
1.5 m (5 ft).
units are for information only.
4.3 Glass Laboratory Funnel, 50 mm in outside diameter, 7
1.3 This standard does not purport to address all of the
mm in stem diameter, 80 mm over-all length.
safety concerns associated with its use. It is the responsibility
4.4 Double-Pole Single-Throw Relay, 115 V, 8 A.
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
5. Preparation for Test
limitations prior to use.
5.1 Assemble the apparatus by slipping one end of the
plastic hose over the funnel stem, and the other end over the
2. Terminology
nuclei counter input nipple.
2.1 Definitions:
5.2 Turn on the electrical supply to the nuclei counter and
2.1.1 condensation nuclei—particles within the size range
allow 30 min warm up time with the input tube sampling the
from 0.001 to 0.1-µm radius.
effluent from a HEPA filter.
2.1.2 HEPA filter—high-efficiency particulate air filter.
5.3 Measure the nuclei concentration at the intake to the
2.1.3 laminar flow—airflowinwhichtheairconfinedwithin
3
HEPA filter. A concentration of less than 1000 particles/cm
the walls of a room or a smaller work station moves as an
indicatesaconcentrationinsufficientforconvenientlydetecting
isovelocity front along parallel flow lines.
leaks in the filter or its gaskets.
2.1.4 leak—a gap or void in the filter media, or in the
5.3.1 In the event that a nuclei concentration of less than
associated gaskets, which permits unfiltered room air to pen-
3
1000 particles/cm occurs when sampling a clean work station,
etrate the clean room or clean work station.
move the work station into a room having a less clean ambient
3. Summary of Practice such as a room not supplied with filtered air.
5.3.2 In the event that the intake nuclei concentration of less
3.1 This recommended practice takes advantage of the fact
3
than 1000 particles/cm occurs in a laminar flow room of the
that a HEPAfilter retains a high percentage of the condensation
ceiling to floor or wall to wall type, make the filter leak test at
nuclei found in ordinary room air. In this recommended
1
This practice is under the jurisdiction of ASTM Committee E21 on Space
2
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.
3
Current edition approved Nov. 1, 2006. Published December 2006. Originally General Electric Co., Schenectady, NY, Model No. 112L482G1 has been found
´1
approved in 1968. Last previous edition approved in 2001 as F91 – 70(2001) . satisfatory.
4
DOI: 10.1520/F0091-06. Tygon tubing or equivalent has been found satisfactory for this purpose.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
F91–06
a time when the room is operating on a full work schedule with gasketed joints at the filter edges. Scan by traversing the filter
the maximum number of occupants. face in straight sweeps from lef
...