Oil Stop Valve, Check Valve are used to prevent discharge of separated oil to sewers/streams. The Oil Stop Valve is fabricated from non-corrosive PVC and stainless steel. It is designed for oil injected screw compressors, rotary screw air compressor. It has only one moving part, a ballasted float set at a specific gravity between that of oil and water. When an oil spill occurs, the float loses buoyancy as the oil level increases until it finally seats itself on the discharge port. Thus, the oil spill is confined. The Oil Stop Valve is the most cost effective method to prevent a major disaster.