The central component is an ultra-reliable, seal-less, magnetically coupled pump that is installed in the liquid refrigerant line between the receiver and the thermal expansion valve, as shown below. The technology is available through Hy-Save, Inc., Portland, Oregon

This Federal Technology Alert (FTA), one of a series, describes the theory of operation, field experience (savings and reliability), range of application, and how to evaluate the LPA for a particular application.

Energy-Saving Mechanism
The LPA is a simple, reliable means of converting a refrigeration system to floating-head operation, which is the efficient operation obtained by allowing the condenser to operate at lower pressure and temperature when ambient conditions permit. In an LRP retrofit, the pump overcomes head losses in the liquid line and dryer that would otherwise cause some flashing (refrigerant boiling) ahead of the expansion valve. With the LRP suppressing flash gas, the condensing setpoint (temperature or pressure) can be changed to a lower value. Little, if any, savings will be obtained by applying LRP to systems that already have floating-head control or that do not operate much during the low ambient temperature conditions necessary to accrue floating-head savings.