10′s of thousands of LPA® pumps have been installed as a simple retrofit means of getting liquid refrigerant to the expansion valves when minimum head pressure controls are set to reduced head pressures, thereby saving energy and increasing capacity at mild to cold outdoor temperatures.
The LPA® pump eliminates the usual problems of capacity loss and poor oil return due to operating with low head pressure.
Improved performance and efficiency of a system that has flash vapor in the liquid line. This is especially apparent if flash vapor is a serious problem, as in systems with excessive liquid line pressure drop, elevation gain in the liquid line, or if the air surrounding the liquid line is warmer than the outdoor temperature.
Reduced scaling problems on water-cooled systems when a small amount of high pressure liquid from the pump outlet is injected into the discharge line, reducing the vapour temperature.

The LPA works by boosting liquid refrigerant through the system…

The LPA works by boosting liquid refrigerant through the refrigeration system. By increasing the liquid’s pressure, the associated saturation temperature is raised, while the liquid temperature remains the same. The liquid becomes sub-cooled; reducing the potential for flashing prior to the expansion valve. With LPA, your business will enjoy higher efficiency, lower power draws and substantial cost savings.

Taken from: http://www.hysave.com/technology/lpa-systems/