The common inlet and exhaust valves on the market at present are divided into 3 categories according to their structural forms: float type inlet and exhaust valves, lever type inlet and exhaust valves, gas new type inlet and exhaust valves.

1. float type into the exhaust valve float type exhaust valve of the large exhaust port exhaust speed is faster. And in the complex water flow with gas under the conditions of its exhaust effect is not good, in only a small amount of exhaust port conditions its effective exhaust volume is small.

2. lever type into the exhaust valve lever type into the exhaust valve work performance is excellent, the disadvantage is that its exhaust port is too small, exhaust speed basically can not reach the water supply pipe into the exhaust operation requirements. 

3. cylinder type into the exhaust valve cylinder type into the exhaust valve its working principle is to use the float lever and other control cylinder pneumatic diaphragm action, so as to control the valve body into the exhaust port open and close. Its characteristics are fast opening and slow closing, exhaust quickly and thoroughly. A small amount of gas can be discharged through the micro-exhaust hole, and when negative pressure occurs in the pipeline, the air can be quickly replenished to reduce or avoid the occurrence of water hammer, so as to meet the operational requirements of water supply in an energy-efficient manner.