Spring Loaded version.
Allows free flow of air however dampens the speed of closing of the air valve due to high velocity of water.
This avoids the slamming of the Air Valve float into the seat & the resultant damage to the float & initiation of the transient pressure wave which has the potential of building–up & leading to a catastrophe.
To e installed in a pipeline before the Air Valve.
Size Range: 25 to 400mm.
Pressure ratings: PN1.0 to PN 4.0 MPa.