Valves to maintain a constant differential oil pressure between oil pump and oil separator.

ORVA OIL-PRESSURE REGULATING VALVES

GEA oil-pressure regulating valves are designed for controlling the oil pressure in the oil circuit of screw-type refrigerant compressors. They comply with the technical regulations of the German Technical Control Board (TÜV). They are mechanically operated regulating devices to maintain a constant differential pressure. Their functionality also considers extreme conditions such as the starting phase of the compressor. The valves are of angle-type design with welding or flanged ends. They mainly consist of a forge body with the connections welded onto it, a tight piston, stem, cover, spring and cap. The oil pressure control valve is located in a bypass between oil pump outlet and oil separator. The amount of oil fed to the compressor varies depending on operational conditions. However it is always less than the amount of oil that is being supplied by the oil pump. The excess amount of oil is being recirculated via the bypass to the oil separator. The oil pressure control valve which is located in that bypass keeps the differential pressure between oil pump outlet and oil separator at an almost constant level. If the oil flow rate to the compressor drops, this differential pressure will increase and cause a further opening the oil pressure control valve. If the oil flow rate to the compressor increases, the oil pressure control valve will close to the point where the differential pressure which has been set at the oil separator is re-established. Regulating the differential oil pressure between oil pump outlet and oil separator enables a simple and constant oil supply to the screw compressor throughout all operating conditions. The sealing at the valve seat is provided by an o-ring seal. After the valve seat has been pressed into the seal up to a pre-defined depth, it collides with the metallic edge of the tight piston.