14
Pre-filters
Pre-filters should be checked each month. In most cases, they should be changed every 1 to 3
months. Prefilter replacement is required when discoloration of the prefilter occurs or when the low
airflow alarm comes on. See the “PRE-FILTER CHECK/REPLACEMENT” section of this manual
for complete instructions.
HEPA Filters
The HEPA filter must be changed atlease every two years. See the “FILTER REPLACEMENT”
section of this manual for complete instructions.
The HEPA filter must be changed every two years or whenever it is clogged. The frequency with
which the filter must be changed depends upon usage. OSHA and the American Conference of
Government Industrial Hygienists (ACGIH) have published guidelines for Threshold Limit Values
(TLV’s) of exposure to chemicals and particulate. Local regulations may also contain specific
TLV’s. It is the express responsibility of the user to follow these regulations.
If the level of the substance being used exceeds the published TLV’s prior to the annual change
date, the HEPA filter must be changed. If the filter is changed prior to the annual date, it should be
changed every two years from this new date.
Pre-filter Check / Replacement
A. To check the Pre-filter:
1. Look through the sash to the inside of your unit. The pre-filter and pre-filter grid are located at the back of
the unit.
2. Look through the slats on the pre-filter grid. If the prefilter is discolored (the original color is green),
replacement is needed.
B. To replace the Pre-filter:
1. Don the proper PPE for handling the substance that have been used inside the hood (refer to the MSDS
sheets).
2. Turn the unit on and make sure that the blower is running.
3. Place an appropriate poly bag on the base of the enclosure. You will place the saturated pre-filter inside
the bag and seal it before removing it from the hood.
4. Remove the 4 black knobs or 6 polypropylene clips that hold the prefilter grid in place. This will expose
the clogged pre-filter. Do not remove the pre-filter from the hood!
5. Remove the pre-filter from the pre-filter grid and place it inside the poly bag. Wipe any residue off of the
pre-filter grid and base of the enclosure. Place the rag inside the bag with the pre-filter and seal the bag.
Dispose of the pre-filter in accordance with your local guidelines for the substances that have been used
inside the hood.
6. Inspect the HEPA filter for blockage. If replacement is needed, refer to the “FILTER REPLACEMENT”
Type B, sub-section of this manual for complete instructions.
7. Place the new pre-filter into the pre-filter grid and secure into place with the 4 black knobs or 6
polypropylene clips.
8. Dispose of your PPE in accordance with your local guidelines for the substances that have been used
inside the hood.
MAINTENANCE
