B8 Hepa Filter Leak Test - Heraeus HS 9 Service Manual

B Field tests
B8 HEPA filter leak test
Purpose of the test:
The test is used to determine the integrity of supply
and exhaust HEPA filters, filter housings, and filter
mounting frames while the cabinet is operated at set
point velocities.
Apparatus:
Aerosol photometer with linear or expanded logarith-
mic scale.
Calibration of the apparatus:
The aerosol photometer must be calibrated in accor-
dance with the manufacturer's instructions or IES-RP-
CC-013-86T (Institute of Environmental Sciences, Mt.
Prospect, Illinois).
Accuracy of the apparatus:
The photometer must be capable of detecting a 100%
upstream concentration with an aerosol concentration
of 10 µg/L DEHS or PAO. The light scattering intensity
resulting thereof is used for comparison measure-
ments.
The photometer must be adjusted so that a value of
100 can be read from the 100% scale.
The photometer must be capable of holding an air
sample volume of at least 28.3 l/min (1 ft³/min). The
diameter of the sample inlet must not exceed 2.5 cm
(1 in).
Auxiliary devices:
Aerosol generator with laskin nossles.
Test conditions:
There must be no objects in the safety cabinets work
chamber. The doors and the windows of the room
where the cabinet is located must be closed (no draft).
Install the measuring device and perform the test
measurement:
NOTE – Connection to exhaust system:
If the cabinet is connected to a facility-internal
exhaust system, the connection to the exhaust system
must be removed to allow access to the exhaust filter.
Figure B9
Fig. B9, Removal of the perforated plate and ex-
haust filter guard
1. Fig. B9: Remove the exhaust filter guard [1]
so that the exhaust opening [2] is accessible
(see section 4.2).
2. Remove the perforated plate [3] from the work
chamber (see section 4.6).
• 52 •
Service Instructions HERAsafe HS/12/18
Valid: 05.2001 / 50060091 / A