Appeal No. 1999-2126 Page 5
Application No. 08/857,938
disclosed in Robinson ‘203, and second by including a double-
walled tube as disclosed in Wilkinson, Gebert or Burhans.
Robinson ‘241 discloses a liquid filter and pressure
regulator in which, just as in the appellants’ invention,
liquid enters an inlet from a supply tank (the dirty side),
flows through a filter into a central tube (the clean side),
and then flows out to the point of use. The liquid that is
flowing out of the device through the central tube (124) also
impinges against a pressure regulator (44), the construction of
which is not described. If the pressure in the central tube
exceeds the operating value of the pressure regulator, liquid
also can exit through a return port (66) to the supply tank.
Robinson ‘203 discloses a pressure regulator comprising a
diaphragm (18) that operates a valve element (24) which
interacts with a valve seat (30). The diaphragm is exposed on
one side to the pressure of the liquid flowing to the point of
use and on the other side to a spring (28) and a vacuum (line
50). The pressure regulator of Robinson ‘203 would appear to
be of the general type that an artisan would recognize as being
contemplated but not described in Robinson ‘241, and we agree
with the examiner that one of ordinary skill in the art would
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