Check valves and dirt separators

A check valve prevents liquid from flowing back when the pump stops, so that the suction line does not drain and the pressure is not released in the wrong direction. A strainer stops debris before it reaches the pump, valve or meter, and its screen can be removed and cleaned. The valves in this category are brass or AISI316 acid-resistant stainless steel for water, liquid and compressed air piping.

A foot valve with a suction strainer is installed at the lower end of the pump's suction line in a tank or well. A threaded check valve is fitted on the discharge side or in the pipeline, and for larger pipes a disc or flap check valve between flanges. Selection proceeds from the medium and material to the thread or flange size, then to the seal according to temperature, and finally to the installation position, as some models are intended for horizontal installation. For brass models, the operating pressure decreases as the size increases, and for hot media there are metal-seated models up to +240 °C.

High-pressure check valves for hydraulic systems are under hydraulic check valves.