Oil separators are designed to separate the oil that is carried out by the refrigerant vapors from the compressor crankcase. They are installed on the pressure pipeline between the compressor and the condenser. The oil is separated by virtue of an abrupt change in the vapor direction and deceleration thereof.

What oil separators are mainly intended for is efficient purification of oil from the pressurized refrigerant’s vapor, and return thereof to the compressor crankcase. This dramatically increases the system’s general performance by preventing excessive oil circulation through the system.

Basically, an oil separator guarantees that oil is returned to the compressor crankcase is the oil level is preserved.


At the oil separator entrance, a gaseous refrigerant that contains the oil in a sprayed form collides with the leading edge of the screw. Driven by the centrifugal force, the oil-and-gas mixture moves along the screw, which in turn causes heavier oil particles to press against the separator’s inner wall where they collide with the filtering element.

The main functions of this filtering elements are removing the gaseous refrigerant from the oil and moving the purified oil to the oil collection reservoir. The separated oil flows down along the sleeve through a separation wall, and reaches the oil collection chamber located at the bottom of the oil separator. A special wall separates the oil collection chamber and eliminates the risk that the oil is entrained again by preventing a turbulent flow.

In fact, the gaseous refrigerant clean of oil exits through the second filtering element, which is installed slightly lower than the lower edge of the screw. Triggered by a special float mechanism, the needle oil return valve helps the separated oil get back to the compressor crankcase or oil receiver. To entrain metal particles that appear during the operation and may negatively affect the needle valve’s performance, there is magnet in the lower part of the oil collection chamber. Oil entrainment efficiency can reach up to 99% given the right choice of the parameters and design.