The D-050 Combination Air Valve has the features of both an air
release valve and an air & vacuum valve.
The air release component is designed to automatically release small
pockets of air to the atmosphere as they accumulate along a pipeline
or piping system when it is full and operating under pressure.
The air & vacuum component is designed to automatically
discharge or admit large volumes of air during the filling or draining
of a pipeline or piping system. This valve will open to relieve
negative pressures whenever water column separation occurs.