Cryogenic Machinery Corp.

Cryogenic Machinery Corp.
TROUBLE POSSIBLE CAUSE CORRECTION
Pump will not prime Wrong rotation Check direction of rotation
Insufficient NPSH Increase NPSH
Liquid not delivered Pump not primed Increase NPSH
Vapor pocket in suction line Check for low points in suction line
Failure to deliver rated capacity and pressure Insufficient NPSH Increase NPSH
Wrong rotation Check direction of rotation
Loss of suction pressure Increase suction pressure
Impeller or Volute pasages clogged or inlet restricted Disassemble, inspect and clean
Wear rings worn Replace
Impeller damaged Replace
Vapor in liquid Increase NPSH
Vapor pocket in suction line Check piping for continuous slope. No point should be lower than pump inlet
Total head greater than head for which pump was designed Cut impeller dia. and re-balance impeller for fixed speed pump. Reduce speed for trailer/variable speed pump
Pump overloads driver Drive failure Repair or replace driver
Flow greater than rated flow Cut impeller dia. and re-balance impeller for fixed speed pump. Reduce speed for trailer/variable speed pump
Pump vibration Insufficient NPSH Increase NPSH
Vapor in liquid Increase NPSH
Worn bearings Replace
Damaged rotating element Replace
Foundation not rigid Increase support
Pump operating below minimum recommended flow Increase flow
Impeller clogged Disassemble, inspect and clean
Impeller rubbing Impeller not tightened securely on shaft Tighten impeller screw
Bearing failure Relace bearings, inspect/replace impeller, seal and wear rings
Excessive pipe loading Eliminate pipe loading in warm and cold conditions
Leakage between pump casings Volute gasket Replace
Excessive seal leakage Sealing surface on seal or rotating ring damaged or worn Replace seal assembly and rotating seal ring
Impeller not tightened securely on shaft Tighten impeller screw


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