Find and compare hydrogen check valves from leading B2B suppliers with technical specifications. Check valves, also known as one-way valves or non-return valves are the valves that permit fluids or gases to flow only in one direction. They feature two ports, one for media intake and another for media output. A check valve’s primary function is to avoid media backflow in the system. Essentially a check valve works by disallowing the flow of media when the pressure at the output is lower than at the input. In this way flow of media only in one direction is secured.