Gorman-Rupp Pumps 66B3-B 407277 and up - Manual (Page 11)

OM−01459 60 SERIES
PAGE B − 4 INSTALLATION
reduce the inlet velocity. Calculate the required
submergence using the following formula based on the increased opening size (area or diameter).
Figure 2. Recommended Minimum Suction Line Submergence vs. Velocity
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
A check valve in the discharge line is normally rec-
ommended, but it is not necessary in low dis-
charge head applications.
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 it is necessary to permit the escape of air to at-
mosphere during initial priming or in the repriming
cycle, install a bypass line (sized so that it will not
affect pump discharge capacity) between the
pump and the discharge check valve. Since this
pump does not use a suction check valve, the dis-
charge end of the bypass line must be submerged
in the liquid being pumped in order to maintain
suction.