The standard universal check valve is designed to automatically close the air duct cross-section in order to prevent free air flow in ventilation systems when the axial fan is not operating.

OZA-KLR valves are gravitational valves: the flaps of such valves open under the action of the air flow (the air speed in the cross-section on horizontal sections should be at least 6 m/s, on vertical sections – at least 4 m/s) and automatically return to the original closed position when the air supply is stopped.

The valves consist of a solid-rolled round body and a simple metal sheet flap, also made of galvanized steel;