Envirco NSF Biohazard Cabinet - Manual (Page 32)

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XVIII. HEPA FILTER REPLACEMENT
The HEPA filters require replacement when the air resistance is such that the
specified air velocities cannot be achieved. Replacement should also be made
when the HEPA filter is damaged beyond repair or if five percent or more of the filter
surface has been patched. Only an Authorized Service Contractor should replace
the HEPA filters.
Filter Removal
Caution: Do not remove the front panel until the cabinet has been
decontaminated.
Remove the front access panel by removing the holding screws. Next, remove the
lower, inner access panel(s) to gain access to the supply air HEPA filter. Finally,
remove the upper, inner access panel to gain access to exhaust HEPA filter.
Loosen the four (4) bolts holding the spring clamp on each filter. The 10448 - EBC
47, 4-Ft Type A/B3 cabinet has a baffle above the supply HEPA filter that must be
removed first. Remove the bolts, springs and bars. The exhaust filter should drop
down for easy removal. The supply air filter may be lifted out of the cabinet. All
used filters should be disposed of by incineration.
Filter Installation
Install the new filters in the same way as the old filters were removed. The filter
media is very fragile and even slight finger pressure on the filter pack itself may
cause damage. Handle the filters by the aluminum frame edges only. Be sure to
replace the baffle on the 10448 - EBC 47, 4-Ft Type A/B3 cabinet.
Tighten the spring clamps until the spring is not quite fully compressed. Do not over-
tighten.
Replace all access panels. A light coat of silicone grease should be placed on the
front access panel gasket before replacing. If the gasket was damaged upon
removal, install a new gasket before reinstalling the panel.
After the HEPA filters have been replaced, a filter leak test procedure should be
performed to verify the filter seals, and a cabinet pressure leak test should be
performed to verify the access panel seal. The airflow velocity should also be
checked and adjusted as necessary.