Appeal No. 1999-1960
Application No. 09/075,631
In the background section of the specification, Frantz
states that one of the problems with drain valves prior to
Frantz is excessive loss of reservoir pressure (column 1,
lines 31-40). In response to the problem, one of the
objectives of Frantz is to cyclically open and close the valve
for draining the liquid matter with a minimum loss of
reservoir pressure (column 1, lines 50-55). In furtherance of
this objective, Frantz provides a control circuit that
operates with a time delay of about
20 seconds between the time the sensor 58 first detects the
presence of liquid matter and the energizing of the solenoid
58 to open the valve (column 7, line 49 through column 8, line
2). Thereafter the valve continues to cycle between an open
cycle of about 0.2 seconds and a closed cycle of about 20
seconds until the liquid matter is no longer detected by the
sensor
58 (column 8, lines 23-38). According to Frantz, this brief
open and relatively long closed operating cycle ensures that
the loss of reservoir pressure in the operation of the drain
valve is minimal (column 8, lines 38-45 and 56-65).
Based on our above reading of Frantz, we do not think one
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