Gorman-Rupp Pumps 82E52-B 1327232 and up - Manual (Page 11)

80 SERIES OM−00825
PAGE B − 5 INSTALLATION
DISCHARGE LINES
Siphoning
Do not terminate the discharge line at a level lower
than that of the liquid being pumped unless a si-
phon breaker is used in the line. Otherwise, a si-
phoning action causing damage to the pump
could result.
Valves
If a throttling valve is desired in the discharge line,
use a valve as large as the largest pipe to minimize
friction losses. Never install a throttling valve in a
suction line.
With high discharge heads, it is recommended that
a throttling valve and a system check valve be in-
stalled in the discharge line to protect the pump
from excessive shock pressure and reverse rota-
tion when it is stopped.
If the application involves a high discharge
head, gradually close the discharge
throttling valve before stopping the pump.
Bypass Lines
If a system check valve is used due to high dis-
charge head, it may be necessary to vent trapped
air from the top of the pump during the priming
process. This may be accomplished by installing a
bypass line from the top of the pump, back to the
source of liquid. The end of the bypass line must be
submerged. The line must be large enough to pre-
vent clogging, but not so large as to affect pump
discharge capacity.
AUTOMATIC AIR RELEASE VALVE
When properly installed and correctly adjusted to
the specific hydraulic operating conditions of the
application, the Gorman-Rupp Automatic Air Re-
lease Valve will permit air to escape through the by-
pass line, and then close automatically when the
pump is fully primed and pumping at full capacity.
Theory of Operation
Figures 3 and 4 show a cross-sectional view of the
Automatic Air Release Valve, and a corresponding
description of operation.
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Й
Figure 3. Valve in Open Position
During the priming cycle, air from the pump casing
flows through the bypass line, and passes through
the Air Release Valve to the wet well (Figure 3).
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Й
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Figure 4. Valve in Closed Position
When the pump is fully primed, pressure resulting
from flow against the valve diaphragm com-
presses the spring and closes the valve (Figure 4).
The valve will remain closed, reducing the bypass
of liquid to 1 to 5 gallons (3.8 to 19 liters) per min-
ute, until the pump loses its prime or stops.
Some leakage (1 to 5 gallons [3.8 to 19
liters] per minute) will occur when the
valve is fully closed. Be sure the bypass
line is directed back to the wet well or
tank to prevent hazardous spills.