DVD Underground Air Valves that can be buried under soil are designed to perform three functions:
1. Venting of large volumes of air on the start-up of the system, while pipelines are filled.
2. Intake of large volumes of air on shut-off of the system, which pipelines are being drained.
3. Discharge of pressurized air pockets during the operation.
Due to its Stainless Steel Sleeve, the valve can be buried under soil. As a result, no need for an expensive valve chamber is needed.
Moreover, it does not require any external isolation valve, due to its integral automatic closing mechanism. The valve can be serviced from a Surface Box and taken out for cleaning or maintenance.