... Brass horizontal exhaust valve high quality and low price E121 Automatic air vent valve1,Summarize This valve use float with ... valve body, because the air pressure, valve body float liquid level down, goes down, its down to the lower ... process.2,constitution Brass valve,valve cap,the float is made of high temperature composite materials.the ... ,caliber 1/2'' Honeywell E121 Brass horizontal exhaust valve