Brass spring loaded check valve
This spring loaded brass check valve is a common valve used instead of a swing type non return check valve. The spring type non return valve reduces noise and the affects of water hammering. Although because of the design, a spring type non return check valve has quite a large resistance through the valve is since the sealing mechanism is permanently obstructing the flow path. Swing type non return check valves provide less resistance as they can move almost entirely out the flows path but swing types rely on pressure and gravity to seal which is not as reliable as a spring check valve.