18
FILTER REPLACEMENT
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.
A. To remove the spent ACFHEPA filter:
1. Turn the unit on and make sure that the blower is running. The safety filter, located in the
top of the workstation, will protect you from any residual powders that might come off of the
saturated primary HEPA filter while replacing it.
2. Place 2 appropriate poly bags on the base of the workstation. You will place the saturated
prefilter and HEPA filter inside the bag and seal it before removing it from the hood.
3. Don the proper PPE for handling the substance that have been used inside the hood (refer to
the MSDS sheets). Remove the 4 black knobs or turn the 6 polypropylene clips that hold the
prefilter grid in place. This will expose the saturated pre-filter.
DO NOT REMOVE THE PRE-
FILTER FROM THE HOOD!
MAINTENANCE
CAUTION: Disconnect the linecord from the power entry module
prior to proceeding.
Figure 10. AC740C Pre-filter clips.
