Parker's Swing Check Valve is an in-line check valve utilizing a spring-loaded, "trap door" type of valve. The valve opens when system pressure approaches 1/2 psi and permits full flow with low pressure drop. As system pressure is relieved, the valve snaps closed, automatically retaining all fluids upstream.
Diesel engine fuel injection systems between the fuel tank and fuel filter
Used with externally mounted oil filters and/or coolers to stop oil back flow
Used in transmission fluid lines on passenger busses for automatic lubrication