Crankcase pressure regulators (CPRs) are designed to prevent a compressor motor from overloading when its crankcase pressure rises above its design working pressure. CPRs are common accessories added on to many low-temperature refrigeration applications, such as walk-in and reach-in freezers. (See "Crankcase Pressure Regulators," June 7.)

The control set point of a CPR will need to be adjusted on the start-up of a new system or any time the valve is replaced. Always refer to the instructions provided by the manufacturer when adjusting these valves. If the manufacturer's instructions are not available, then these guidelines can be helpful.