Shuangda Hydraulic Machinery is one of the professional s check valve manufacturers and suppliers in China,Website:://.chinahydraulic-valve.com, welcome to buy cheap and low price s check valve made in China from our factory.Usage and characteristicCheck valve S type is cone structure which allows free flow in one direction and prevent flow in the reverse direction . The structure is simple but the function is reliable. The pressure loss is low. It is mainly used at the exit of a pump as a back valve and a check valve.