Shi check valve: commonly used in pumps with three valves, pumps and motors to prevent the reversal, the general level of the installation, and only dress, big ring, the switch is not stable when the water hammer shortcomings. 2, lift check valve: this valve flap valve closing stroke is only nominal diameter of 1/3, close more quickly. Derive the vertical lift check valve and silencer, muffler check its noise, open and close rapidly, short length of the structure, low cost and in the water supply and drainage, urban construction, has been widely used in the municipal sector. 3, wafer check valves 4, micro Slow Close Check Valve (HH44X) installed at the outlet piping or pumps to prevent water hammer when the media back to stop the pump, the pump reverse impact safety device applies to drainage, fire protection, HVAC and other systems. Advantages:? Open water moment, open-degree, fluid resistance eliminate water hammer design innovative, reliable sealing performance, wear resistance, long life with the help smooth running, no vibration, no noise??. Disadvantages: bulky, cumbersome appearance, higher raw material costs 5, butterfly valve (HH49X HH46X HH47X HH48X DHH44X) primarily by a double flap valve plus buffer device can be configured, can be used to clean water, the source of water, sewage, supply, drainage water and other media trail, installed in the pump outlet stalk to cut off back medium, eliminating destructive atomic Chung water, protect the safe operation of pipelines and pumps. Advantages:? Body is small, light weight management, only about one-third the length of the structure of the swing check valve slow closing excellent system performance is not affected by the pipeline medium speed valve to shut off after a slow, you can? Chung prevent damaging water. ? Rubber thread red, smooth opening and closing, no vibration, no noise? Than the old valve flow resistance is small, there is significant energy savings. 6, the ball check valve with rubber bag breaking ball rolling for the valve, in the role of the media, can be used to scroll up and down on the body of the integral chute to open or close the valve, good sealing performance, muffler just closed, does not produce water hammer, all-water channel valves, flow, low resistance, the head loss than the swing is 50% smaller, horizontal or vertical installation can double. For cold water, hot water, industrial and domestic sewage pipe network, is more suitable for submersible sewage pump. HQ44X: single sphere Microresistance ball valve HQ45X: double ball check valve ball Microresistance 7, rubber disc check valve in the rubber flap from steel, steel bars and reinforced nylon cloth substrate coated outer rubber made valve switch life of up to one million times, the whole flow area design, with head loss is small, easy accumulation of debris, easy maintenance and other features. To apply for horizontal installation of the main drainage system can be installed on the pump at the outlet, the water back to the pump and water hammer damage, can also be installed on the tank and out of water bypass pipe to prevent water back to water supply system. Generally applicable to clean media, not suitable for containing solid particles and the viscosity of the medium. 8. Silent Check Valve