Most HEPA air filter units are constructed the
same way — a continuous length of filter paper is folded back
and forth into pleats and corrugated separators are inserted
between each fold. The assembly is then sealed into a rigid,
open-faced rectangle. The components of a fabricated HEPA
filter include:
(1) Extensively pleated filter medium.
(2) Separators that provide air passages and
keep adjacent pleats apart.
(3) A rigid filter case that encloses and
protects the fragile filter medium.
(4) Sealants used to bond the filter pack
(consisting of the assembled pleated medium and separators)
to the filter case and to eliminate leak paths between filter
pack components.
(5) Gaskets attached to the filter case on
one or both open faces to provide an airtight seal between
the filter and the mounting frame.
Some filter construction methods form the
filter paper on the papermaking machine using an interval
means to keep the adjacent folds apart, thereby eliminating a
need for corrugated separators. The illustration below shows
the assembled components of an open-face, deep pleat HEPA
filter with corrugated separators.
