These types of valve (Non Return Valves) are used to stop back flow to the upstream side of the valve. The design of Check Valve (Non Return Valve) is very simple. A hinged door is placed inside the Swing Check Valve body. With the pressure coming upstream the door is held open; when pressure increases on the downstream side, it forces the door to valve close, stopping any back flow. Mostly all pump discharge line check valves being used. Swing type check valve is performing in vertical and horizontal both line. Lift check valve have have vertical and horizontal both type of design to suit as per line. Flanged End, Check Valves are Swing Check type and the ]class check valves are Piston Type Lift Check Valves. The piston type valve works up and down providing a strong, firm seal under high pressure conditions.