Tianjin U-ideal Rapid Startup Air Vents; Air release valve  for Water Systems
AV600 Air valve :Vent valves for continuous operation, suit for contaminated and foaming mediacompletely 316L, deep drawn - housing surface finish Ra ≤ 1.6 microns | maintain owing to the clamp system | corrosion resistant, very lightweight and compact | available in special materials, eg. as seawater-resistant stainless steels, titanium, Hastelloy, etc.
When water is pumped through the system, the initial air inside the piping is pushed into the air vent by the pressure of the flow. The float remains in the lower part of the air vent, allowing the valve to remain open and air to be rapidly discharged.
After the initial air has been discharged, water begins to flow into the air vent, causing the float to rise and close the valve.
Once the valve closes, it will remain closed and will no longer discharge air even if more air flows in and the water level inside the air vent drops.
Only when the pressure inside the vent approaches vacuum conditions will the valve open again, allowing air to enter and water to drain. 

Design Features:
Air Release Valves function to release air pockets that collect at each high point of a pressured pipeline. Air Release Valves can open against internal pressure, because the internal lever mechanism multiplies the float force to be greater than the internal pressure. This greater force opens the orifice whenever air pockets collect in the valve. Air Release Valves are essential for pipeline efficiency and water hammer protection.

Why remove air from a water system?
Every building services engineer knows that air trapped in either a hot or chilled water system can cause
trouble, such as excessive noise, corrosion and increased maintenance costs. Air can cause air locks which inhibit the filling of the system or the priming of pumps. It can seriously affect the accuracy of flow measurement meters and regulating valves. Under extreme conditions it may even temporarily decommission plant.
Air and other incondensable gases considerably reduce heat transfer efficiency. A film of air 1 mm thick
presents the same barrier to heat transfer as a wall of copper 13 m thick!
Entrapped air in any water system is a threat to thermal efficiency. It is particularly damaging in a chilled water system which does not have the natural deaerating ability of hot water.