Oil Pressure Safety Control

Oil Pressure Safety Control

A major percentage of all compressor failures are caused by lack of poper lubrication. Impoper lubrication or the loss of lubrication can be dur to a shortage of oil in the system, logging of oil in the evaporator of suction line due to insufficient refrigerant migration or floodback to the compressor crankcase, failure of the oil pump, or improper operation of the refrigerant control devices.

Regardless of the initial source of the difficulty, the great majority of compressor failures due to loss of lubrication could have been prevented. Although proper system design, good preventive maintenance, and operation within the system´s desing limitations are the only cure for most of these problems, actual compressor damage usually can be averted by the use of an oil pressure safety control.

An oil pressure safety control with a time delay of 120 seconds is a mandatory requirement of the copeland warranty on all copelametic compressors having an oil pump. The control operates on the differential between oil pump pressure and crankcase pressure, and the two minute delay serves to avoid shut down during short fluctuations in oil pressure during start-up.

A trip of the oil pressure switch is a warning that the system has been without proper lubrication for a period of two minutes. Repeated trips of the oil pressure safety control are a clear indication that something in the system desing or operation requires immediate remedial action. On a well designed system, there should be no trips of the oil pressure safety control, and repeated trips should never be accepted as a normal part of the system operation.

The oil pressure safety control will not protect against all lubrication problems. It cannot detected whether the compressor is pumping oil or a combination of refrigerant and oil. If bearing truble is encountered on systems where the oil pressure safety control has not tripped, even though inspection proves it to be properly wired, with the proper pressure setting, and in good operating condition, marginal lubrication is occurring which probably is due to liquid refrigerant floodback.