GORMAN-RUPP OM--04760 User Manual

Page 11

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PAGE B -- 5


minimize the chance of plugging.


low discharge head applications (less than 30

feet or 9 meters), it is recommended that the by-
pass line be run back to the wet well, and located 6
inches below the water level or cut-off point of the
low level pump. In some installations, this bypass
line may be terminated with a six-to-eight foot
length of 1 1/4 inch I.D.

smooth-bore hose; air and

liquid vented during the priming process will then
agitate the hose and break up any solids, grease,
or other substances likely to cause clogging.

A bypass line that is returned to a wet well

must be secured against being drawn into

the pump suction inlet.

It is also recommended that pipe unions be in-
stalled at each 90_ elbow in a bypass line to ease
disassembly and maintenance.


high discharge head applications (more than

30 feet), an excessive amount of liquid may be by-
passed and forced back to the wet well under the
full working pressure of the pump; this will reduce
overall pumping efficiency.

Therefore, it is recom-

mended that a Gorman-Rupp Automatic Air Re-
lease Valve be installed in the bypass line.

Gorman-Rupp Automatic Air Release Valves are
reliable, and require minimum maintenance. See
for installation and theory of operation of the Auto-
matic Air Release Valve. Consult your Gorman-
Rupp distributor, or contact the Gorman-Rupp
Company for selection of an Automatic Air Release
Valve to fit your application.

If the installation involves a flooded suction such as
a below-ground lift station, a pipe union and manu-
al shut-off valve may be installed in the bleed line to
allow service of the valve without shutting down the
station, and to eliminate the possibility of flooding.
If a manual shut-off valve is installed

anywhere in

the air release piping, it

must be a full-opening ball

type valve to prevent plugging by solids.

If a manual shut-off valve is installed in

a bypass line, it must not be left closed

during operation. A closed manual shut-

off valve may cause a pump which has

lost prime to continue to operate with-

out reaching prime, causing dangerous

overheating and possible explosive

rupture of the pump casing. Personnel

could be severely injured


Allow an over-heated pump to cool be-

fore servicing


Do not remove plates,

covers, gauges, or fittings from an over-

heated pump. Liquid within the pump

can reach boiling temperatures, and va-

por pressure within the pump can cause

parts being disengaged to be ejected

with great force. After the pump cools,

drain the liquid from the pump by re-

moving the casing drain plug. Use cau-

tion when removing the plug to prevent

injury to personnel from hot liquid.


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 2 and 3 show a cross-sectional view of the
Automatic Air Release Valve, and a corresponding
description of operation.