SINGLE ORIFICE AIR VALVE
Nominal pressure: PN0.6-1.6MPa
Nominal diameter:DN16-25mm...
PN16 PN25 DN1 1/2"- 6"

it's automatic valves. They can exhaust gas in the pipeline to reduce energy loss of pipeline system. So they are products of energy ecomonized. The suitable working prssessure is PN10 PN16 and PN25.