Check valves are applied to ensure fluid flow in one direction only. They protect the system against backflow. The check valves can be of different construction (ball, poppet, flap, diaphragm). The check valves open when the difference between the pressure at both sides of the valve (opening pressure) reaches the value needed to overcome the spring load or gravitation.
Filters are used to catch and remove mechanical impurities away from the system.
The check valves and filters must be installed according to the direction of flow, which is usually marked on the valve body. A specific type of check valves – foot valve – is installed in a vertical position at the end of the pump suction line. It protects against the backflow of the fluid sucked up by the suction pump.
The check valves are manufactured from brass or stainless steel (body), brass, stainless steel, plastics (mechanisms). Filters (strainers) are made of stainless steel. Working pressure of industrial check valves and filters up to several tens of bar.
The check valves and filters are used in all industries.