Appeal No. 1997-1155 Page 6
Application No. 08/376,199
of securing the filter element in a casing as taught by Gordon as such would only entail the
substitution of one securing means for another (final rejection, pages 2 and 3).
While the appellants do not dispute that the compressible sorbent filter material used in
their invention is a known material for use in respirators (see appellants' specification, page 9),
there is no suggestion in the prior art applied by the examiner in rejecting the claims to utilize
the compressibility of such filter material by inserting it into a more rigid (or less compressible)
retainer to form an air-tight seal with the retainer wherein the filter material is compressed upon
insertion of the filter into the retainer, as called for in independent claim 1. Looking first to the
teachings of Tayebi, even if the flexible filter material 17 does comprise sorbent granules united
in the form of a porous unified body as required by claim 1, Tayebi, as discussed above,
provides no teaching or suggestion that the filter element is compressible and compressed in the
direction normal to fluid flow when inserted within the retainer 19 in the Figure 3 embodiment
or when the cartridge is inserted within the collar 38 in the Figure 8 embodiment or that the
filter would be capable of achieving acceptable filtering if so compressed. Gordon, on the
other hand, evidences that it is known in the filter art to retain a sponge rubber filter element in
a shell such that the sponge rubber filter is compressed in the direction normal to fluid flow so
that it bows outwardly. As the teachings of Gordon are directed to a sponge rubber filter
element and not to a filter comprising sorbent granules united in the form of a porous unified
body as required by claim 1, we agree with the appellants that Gordon, even if combined with
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