Appeal No. 1997-3304 Page 10
Application No. 08/181,936
change in volume due to the pressure differential, and this
results in the formation of recirculating gas cells (41).
Philipossian goes on to indicate (col. 5, lines 40-45) that
"[a]s has been determined by the prior work of others, the
optimum shape for suppressing re-circulation cells of entering
reactant gases is obtained by increasing the curvature of
[t]he sidewalls of the nozzle in the direction of theoretical
flow streamlines." Thus, the gas flow problem confronted by
Philipossian is improved by replacing the sharp corners with a
cone-like shape (40) (col. 5, lines 14-45). The cone-like
shape (40) shown in Philipossian's Figs. 1 and 2 is like the
appellants' embodiment of Fig. 3. Philipossian also describes
an alternative embodiment (col. 3, lines 1-3), shown in Fig.
10, which is like the appellants' embodiment of Fig. 2.
Given the collective teachings found in the appellants'
admitted prior art (specification, pages 1 and 2) and in
Philipossian, it is our opinion that a person having ordinary
skill in the art, knowledgeable of the gas flow problem
resulting from the sudden pressure change between the pipe and
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