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Gorman-Rupp Pumps 81 1/2E3-X1.5 3P 387385 and up User Manual

Page 11

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OM−00770

80 SERIES

PAGE B − 4

INSTALLATION

tance equal to at least 3 times the diameter of the
suction pipe.

Suction Line Positioning

The depth of submergence of the suction line is

critical to efficient pump operation.

Figure 2 shows

recommended minimum submergence vs. veloc-
ity.

NOTE

The pipe submergence required may be reduced

by installing a standard pipe increaser fitting at the

end of the suction line. The larger opening size will

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

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.

A check valve in the discharge line is normally rec-
ommended, but it is not necessary in low dis-
charge head applications.

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.