AAF International Front Access Housings - Manual (Page 12)

Repeat the process of gas phase cassette installation and sealing
until all housings are filled with sealed cassettes as shown below.
3.7 Prefilter Installation: The prefilter is offered as an option with the
FAH. It is normally not necessary to include the prefilter if the system
includes a separate bank of inlet filters. Where a separate inlet filter
system is not provided, it is highly recommended that prefilters be
used to prevent the build up of lint and dust on the face of the gas
phase chemical filters.
Install the prefilters as shown in the sequence at right. Each individual
FAH can accommodate one prefilter. A standard 24 x 24 ASHRAE
style filter will fit into the size 202 housing and a standard 24 x 12
ASHRAE style filter will fit into the size 201 and 102 housings. The
Front Access Housings are designed to accept a 2 deep pre-filter
only. For best results AAF recommends the use of the MERV 7 rated
PerfectPleat.
Place the prefilter into the open face of the FAH with the pleats
arranged vertically. However, it may be necessary when installing
some half size filters to arrange the pleats horizontally.
Step 1: Insert the prefilter into the FAH.
Step 2: Engage the two spring loaded prefilter holding tabs.
Step 3: The installed prefilter.
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