First, use: 1. Mainly used to prevent the media back 2. For ammonia, F22 and other refrigerants as the working fluid cooling system 3. Valve diameter: diameter pipe which can be equipped with, if not the same size, used for the liquid tube can be used to great use in the exhaust pipe can be to a small selection. 
 Second, the working principle of: 1. Check valve only allows fluid flow in one direction along the arrow, the fluid is reversed by the spring force and counter-pressure to the valve closed. DN125 The following are the drum with a spring structure, you can flow along a horizontal arrow, up, down, tilt the installation. DN150 for the horizontal structure, no spring, thanks to gravity and back pressure valve closed, so must be installed upright. 2. Have a damping valve, opening and closing balance, the spool easily damaged, can be a pulse in the circumstances. 

 Third, the technical performance: maximum working pressure 4.0Mpa, working pressure of 2.5Mpa, check the product specification implementation GB/T12233-1989 series. 

 Fourth, storage, maintenance, installation and use: 1. Valves should be stored in dry, ventilated room, should be blocked at both ends of the valve channel. 2. Long-term storage of the valve should be checked regularly to remove dirt .3. Should be carefully checked before installation and use requirements of the valve flag is in line valve cavity and the flange surface is dirt, check the valve stem and spool whether the cable wiring between the springs.