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Filtration Table of Contents
HEPA Air Filter Supplier
The HEPA air filter case is constructed of materials
that correspond to the specific application, filtration
requirements, and considerations of disposal ease and cost.
Commonly used case materials include fire retardant plywood,
chromized carbon steel, and alloys UNS S30400 and UNS S40900
stainless steels. The minimum thicknesses required to
maintain rigidity under compressive loads ranging up to 1,400
pounds when the filter is clamped to a mounting frame, are
3/4 inch for wood and manufacturer’s standard steel sheet
gauge for steel. Grade A-C, American Plywood Association (APA)
PS-1 fire-retardant-treated plywood is acceptable, but the
“A” face must be on the inside, facing the pack, and
should be assembled with this face completely coated with a
sealant to close off any leak paths. The outer face should be
filled and sanded as smooth as possible (for plywood). This
is particularly important for industrial plant workers whose
gloved fingers and hands must not be punctured by splinters
from a wooden frame when replacing filters. For wooden case
filters, case panels may be joined with riveted joints,
which are assembled by gluing with an adhesive and double
nailing or doubling screwing with coated box nails,
corrosion-resistant plated screw nails, or flat-head wood
screws. The end points of the fasteners must not penetrate
the inside or outside surfaces of the case. Metal cases
should be used in instances of potential wetting or high
humidity at elevated temperatures and when the filter will be
exposed to corrosive chemicals.
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