Air valve is the respirator of pipeline and the safeguard of pipeline safety. It is also called ventilation valve and exhaust valve, but it has suction function, so it is more accurate to call air valve.

for common pipes, this negative pressure will not cause harm. If the stiffness of some pipes is not enough, such as large thin-walled steel pipe, it is easy to cause the deformation of pipe geometry, resulting in leakage failure. At the same time, the sewage and sludge outside the pipe will be pumped into the pipe, endangering the safety of water supply.