Barberi® check valves are monodirectional devices, allowing the backflow prevention of fluid under pressure. According to the model, they are normally used in domestic water installations, booster pump systems, heating systems, central heating systems, heat generators (wall-mounted boilers, solid fuel generators, heat pumps). Sealing is permitted through forces exerted by a spring and by the fluid pressure against a gasket which guarantees the seal even at very low back pressures. Moreover, the force of the spring allows the valve to have a universal characteristics concerning the installation position. The peculiarity of this valve is the presence of two side drains (test ports), upstream and downstream of the check valve insert respectively. The side drains are used to verify the correct working of the check valve (test port upstream of the check insert) and to drain the system (test port downstream of the check valve). This valve can be used as antipollution device in systems with potable water.