Clogged oil filter(s) or faulty bypass valve in the filter(s).
Defective pressure transducer or pressure gauge.
Faulty pressure transducer cable.
Pump Running Rough
Insufficient suction head for the demand at the pump speed in which the rough running occurs. Check
for obstruction in the suction line, for solids that have collected in the suction line restricting flow, for a
partially closed valve, or if the centrifugal pump was not sized properly to provide 50 PSI at the pump
inlet at max rated RPM of the pump. If the inlet pressure gauge needle is oscillating radically, then the
pump is cavitating due to one or more of these reasons. A cavitating pump will shake the entire well
service unit.
Valve leaking, broken spring, or broken valve guide.
Air in the fluid entering the pump.
Ruptured suction stabilizer bladder, the bladder has lost its nitrogen charge, or the charge pressure was
set too high. A properly charged suction stabilizer is set to 30-40% of the operating suction line
pressure.
Pump is operating at the same pressure as the pressure relief valve, and the valve is cycling open and
closed.
Solids in the pumping medium are trapped between the valve and valve seat.
Valve insert is damaged or missing. Valve guide legs are damaged or missing.
Pumped fluid is hot, causing flashing of the fluid during the suction stroke.
Broken or worn internal moving parts.
Cracked fluid end.
Loss of Pumping Pressure
Valve leaking due to damaged or missing insert, broken spring, or broken valve guide.
Leaking or improperly set pressure relief valve.
Overpressure resulting in subsequent failure of rupture disk safety devices.
Insufficient suction head for the demand at the pump speed in which the pressure drop is occurring.
Check for obstruction, solids that have collected in the suction line restricting flow, a partially closed
valve, or if the centrifugal pump was not sized properly so that it will provide 50 PSI at the pump inlet at
max rated RPM of the pump.
Ruptured suction stabilizer bladder, the bladder has lost its nitrogen charge, or the charge pressure was
set too high. A properly charged suction stabilizer is set to 30-40% of the operating suction line
Revision K 03/12/2019
MSI - A Division of Dixie Iron Works, Ltd. All rights reserved.
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