I. Features SD9000-16 / 25P piston type water hammer arrester can without the need to prevent fluid movement of people, effectively eliminating irregular water hammer wave outside water hammer and surge generated by various types of fluids may occur in the transmission system shock, so as to eliminate destructive shock wave, serve the purpose of protection. Second, the principle SD9000-16 / 25P eliminate water hammer piston's inside a closed container gas chamber, the lower end of a piston, when the shock into the water hammer arrester, water hammer wave acting on the piston, the piston will go Yung cavity direction. Stroke and capacity of the gas pressure in the gas chamber piston movement, water hammer wave size of the piston in the gas and the dual role of certain irregular water hammer pressure up and down movement, the formation of a dynamic equilibrium, thus effectively eliminating the irregular water hammer shock wave.