Crankcase blow-by gas is produced when combustion gases under high pressure escape past piston rings into the crankcase. As these blow-by gases pass though the crankcase, they become contaminated with oil mist. In enclosed areas, like generator sets or engine rooms, the contaminated gas coats and damages surrounding equipment, resulting in hazardous conditions and the need for costly maintenance. Uncontrolled blow-by oil mist also coats engine after-coolers and turbochargers, which reduces cooling capacity and engine efficiency.

Racor's Crankcase Ventilation Systems prevent this problem by removing mist and contamination in blow-by gases. In closed systems (CCV), the high efficiency filter prevents fouling of the turbocharger and after-cooler. In open systems (CV), it prevents fouling of surrounding equipment and walls, thus allowing clean exhaust to vent directly to the atmosphere.

The systems have stainless steel latches for tool-less element change and a metal housing (steel for the 4500 unit and aluminum for 6000, 8000 & 12000 units) with an epoxy powder coating. They also have a drain check valve, which allows collected oil to return to the crankcase, resulting in drastically reduced oil consumption.

Open systems are acceptable for certain engines and situations. However, in recent years, environmental concerns and legislation to control crankcase emissions have increased significantly. New laws to further reduce the total emissions of engines often make it necessary to close the crankcase breather system. In this case, blow-by gases are routed into the inlet of the turbocharger where they can be burned instead of polluting the environment.