Shuangda Hydraulic Machinery is one of the professional right angle check valve manufacturers and suppliers in China,Website:://.chinahydraulic-valve.com, welcome to buy cheap and low price aj right-angle check valve made in China from our factory. Usage and characteristic Both in-line check valve type A and right-angle check valve type AJ are cone structure which allows free flow in one direction and prevent flow in the reverse direction .It has a spring in it to keep valve close. 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.