Air vent and drain valves are crucial components of piping systems, but they don't always need to be open. They must be closed when their function is no longer required, such as after all gas, water, and other liquids have been discharged from the system, or when maintenance or replacement is needed during system operation.
Before closing air vent and drain valves, all other valves in the piping system must be closed to prevent liquids or gases from flowing into them and affecting their normal operation.
In short, air vent and drain valves are vital components of piping systems, with a wide range of functions and applications. Their operation must be set and closed according to specific circumstances to ensure the normal functioning of the piping system.
