I sat in on the Pump Guy Seminar this week in Philly, and an interesting discussion came up about the role control valve can play in proper pump operation.
One of the examples cited involved replacing a check valve with a backflow preventer in the discharge piping of a pump. This will increase the cumulative resistance in the systems and drag the pumps to the left of best efficiency on its performance curve. When the operator sees this, he could open the control valve on the discharge side of the pump, relax the resistance on the system, and allow the pump to slide back toward best efficiency.
Another example is, if you’re pumping into a pressure vessel and suddenly the safety valves discharges on a downstream header, you will be going to lose all resistance in the system, slamming the pump’s duty point out to the far right of the best efficiency zone. In this situation, the pump is going to vibrate, the pump may overload the electric motor, and the pump may go into cavitation. The operator can save this pump from damage by restricting the control valve.
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Class 150 Carbon Steel Ball Valve
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