Page 254 - Know and Understand Centrifugal Pumps

Avoiding Wear in Centrifugal Pumps

k RELIEF VALVE
PROCESS
PRESSURE
I

I I
Figure 16-3

financial guide to lower future capital investment do this. With this in
mind, no wonder we have to extensively throttle the discharge in order
to achieve our necessary flow rate. Yes, this saves future capital
investments, but creates present problems with the daily maintenance
budget. Excessive throttling of the discharge valve results in severe
punishment to the pump.
Consider Figure 16-3. This pump is draining a tank and discharging
into the process stream. If a control valve should be strangled to a
certain predetermined pressure (resistance), the pressure relief valve
automatically opens and the excess discharge pressure recirculates back
to the suction tank. The pump never knows that the discharge control
valve is throttled. If this situation exists in your plant or if the operators
regulate the flow by manipulating control valves, this will be the proper
design to extend the useful life of your pump.

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