An air operated valve, also called a hydraulic valve, is a kind of power-driven valve that applies air pressure to the opening of a gas valve. You may find valves with both an open and closed position. The valves are usually placed in the exhaust system of your vehicle. These air valves are available in wide varieties with various names and brands. The most common type is the Vacuum tube valve. Another type is the Inflation port, which is similar to the overflow port. A third type is a closed valve, which is like the inset or flush valve. For Air valve, simply call AVK Singapore.