P21X-0.6W air vent valve is for heating systems auto air venting like boiler, large pipeline and container, solar heaters, central air-conditioning. It's often fitted at the highest point on a pipeline to continually release unwanted air during system operation to protect against unwanted surges and maintain system efficiency. The valve seat are protected by filtermesh which effectively prevent inpurities clogging exhaust nozzle. Exhaust nozzle is connected with wastewater pipe which leads water leaked by inproper use into sewer.

The Working Principle of Vertical Exhaust Valve: 

When the water has not entered the exhaust valve, the valve is open, the float falls vertically at the bottom of the valve. The thimble staies inside the base. When the water entered the valve, the float vertically rise because of the effect of buoyancy. When the air in the valve increases,the surface of the water decreases. Now begin to exhaust. After the gas discharged, the valve became sealed.