https://www.tdbvalve.com/product/valves/gas-valves/ A brass gas valve is a type of valve that is commonly used in gas piping systems to control the flow of natural gas or propane. These valves are made of brass, a durable and corrosion-resistant metal that is well-suited for use in gas systems. The valve is typically operated manually, using a handle or knob that can be turned to open or close the flow of gas.