gate-type check valve

gate-type check valve

A type of one-way valve that uses a swinging gate, or flapper, to control fluid flow. In a multiengine aircraft vacuum system, they are used to isolate one of the pumps in case of the failure of the other. The flapper is at right angles to the flow when the valve is closed and parallel when it is open. The gate-type check valve prevents possible damage to instruments by engine backfire, which would reverse the flow of air and oil from the pump.