Heraeus HS 9 Service Manual page 82

Service Instructions HERAsafe HS/12/18
B Field tests
B8 HEPA filter leak test
1. Fig. B10: Route the hose [5] of the aerosol gen-
erator [6] so that the aerosol is introduced into the
cabinet upstream of the HEPA filter
2. Connect the hose [3] from the photometer to the
cabinet upstream sample port tubing (Decon-
taminate tubing before opening).
3. Turn on the aerosol generator.
4. Using the photometer [4], measure the aerosol
concentration and check to see if the light scat-
tering intensity is in accordance with comparison
measurements of a minimum10 µg/L DEHS or
PAO.
5. First, scan the downstream side of the downflow
filter [2] at a distance of 2.5 cm (1 in) from the filter
surface in slightly overlapping strokes. The scan-
ning rate must not exceed 5 cm/s (2 in/s).
6. Next, scan the cross-joints in the downflow filter
and plenum area.
7. Scan the downstream side of the exhaust filter [1]
at a distance of 2.5 cm (1 in) from the filter surface
in slightly overlapping strokes. The scanning rate
must not exceed 5 cm/s (2 in/s).
8. Also scan gaskets
Acceptance according to NSF, 49, Annex F:
The aerosol penetration does not exceed 0.01% at
any point.
Troubleshooting:
Excessive aerosol penetration:
Seal minor leaks at the mounting frame of the
downflow filter with silicone.
Replace the downflow filter. Retighten the retain-
ing screws on the plenum frame.
Replace the exhaust filter. Retighten the wing nuts
for the filter housing.
Valid: 05.2001 / 50060091 / A
Figure B10
Abb.10, Test with photometer
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