NOTICE:
On glass-lined pumps, the thermal shock limit of the glass varies with the conditions of opera-
tion. Do not introduce liquid to pump if temperature difference between liquid and pump is
100°F. Gradually heat pump before introducing hot liquids.
1.
Suction Supply Above Pump
When pump is installed as shown below, pump will prime itself.
1. Float switch
2. Air vent valves
2. Suction gate valve
3. Discharge gate valve
Figure 41: Self priming
a) Open gate valve on suction and dose discharge gate valve.
b) Open air vent valves until all air is expelled and water flows through openings.
c)
Close air vent valves, start pump and open discharge gate valve. Pump will continue to be
primed for any future starting.
This method is the simplest and, particularly for automatic operation, the safest. A float switch in the
suction reservoir can be arranged to stop pump, should there be failure of liquid supply.
2.
Prime with Foot Valve
With pump installed on suction lift, with foot valve at end of suction line, priming can be done any of
the following three ways: In methods (1) and (2), the pump will remain primed, provided foot valve is
tight. Any failure, however, of foot valve when pump is standing idle, will permit the pump to lose its
prime. During long idle periods, the pump can also lose its prime through leakage from stuffing box-
es.
a) Outside Supply: Close discharge gate valve, open air vent valves and open valve in priming
supply line until all air is expelled and water issues from vent openings. Close air vent valves,
close valve in priming supply line, and start pump; then open discharge gate valve.
5.14 Priming
3175 Installation, Operation and Maintenance Instructions
39
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