Tuesday Tip: Troubleshooting Refrigeration Pumps

Cornell Pump has been manufacturing (and troubleshooting ) refrigeration pumps since the 1950s. Our open drive CB Series has been a consistent performer for decades, and our Arctic King line of hermetic refrigeration pumps has proved very popular since introduction in 2013.

Here are some symptoms, possible causes, and corrective actions to take when dealing with Cornell’s CB (open drive) and HT (semi-hermetic) series refrigeration pumps.

MECHANICAL PROBLEMREMARK CORRECTIVE ACTION
Loss of prime at start-upVolute vent line feeds to another line instead of directly into the receiverVolute vent piping should be directly into the separator above the maximum liquid level
Vent line closedOpen volute vent line
Pump started before completely filled with liquid or before cooled downFollow the “start-up instructions”carefully and allow ample time forsystem to balance and pump to cool down
Pump started with discharge valvefully open Throttle discharge valve at start up to almost shut-off and open it very gradually
Loss of prime during operationCavitation Cavitation due to an excessive flowrate, the closing of the stop valve will bring about immediate recovery—adjust the hand expansion valves as necessary to bring the flow rate within NPSHA limitations
RecirculationUtilize a bypass line to ensureminimum flow requirement
Vapor entrainmentEvaluate false load condition
Reduce rate of temperature draw down in receiver by the compressors
Raise liquid level in receiver
Motor overloading new installationIncorrect rotationEnsure proper rotation
Incorrect pump selectionReview performance conditions and consult factory
Incorrect hand expansion valvesetting Adjust the hand expansion valves as necessary to bring the flow rate within NPSHA limitations
Motor overloading existing installationOil indigestion from system Check amperage and voltage, compare with normal power, oil ingestion will increase power requirement and potential tooverload the motor
External seal (characteristics) leak (only on open drive pumps/ not HT)Failure of outboard mechanical seal assembly Mechanical seal replacement required with a Cornell mechanical seal replacement kit
Internal seal leakFailure of inboard mechanical sealassembly Replace mechanical seal with a mechanical seal replacement kit Characterized by high oil consumption but no visible oil leak
/**/