Appeal No. 98-3303
Application 08/568,211
surface of the plunger 18 spaced away from the interior
surface of the pump barrel 12 in the applicator of Collins
(Fig. 1) such that there is no frictional contact between the
outer surface and the interior surface; the relationship of
the plunger, pump barrel, and packing 22 (page 2, lines 27
through 32) providing for a reduced effective area of the
plunger (as compared to the area of a typical piston type
plunger in sealing relationship with the interior surface).
We also appreciate that the applicator of Collins
includes a flexible tube 29 which carries a conventional spray
gun 30 intended to apply very poisonous material held in tank
1. As expressed by the patentee (page 3, lines 17 through
22), to clear the hose the plunger must be drawn out, allowing
ball valve 14 to open; then, if the trigger on the spray gun
is tripped, the liquid in the hose will run back to the tank.
As argued by appellants (brief, page 3), and as
acknowledged by the examiner (answer, page 6), the hose
clearing operation would be precluded by the proposed
5
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