Check valves allow flow in one direction and automatically prevent flow in the opposite direction. Δ This valve is mainly used in the fluid system containing strong oxidative mediums, like water supply system, heat supply system and acid system etc. It is always used as accessory of boilers. It has exquisite profile and simple structure. Its spring device functions to speed up the closing movement of the disc so as to eliminate water hammer. This valve is very suitable for space-limited locations.