Water valve

A valve is a mechanical device that blocks a pipe either partially or completely to change the amount of fluid that passes through it. Most valves in a residential plumbing system are part of the water supply system and depending on the design of the valve, they may be best suited to simple on/off control of the water flow or instead for adjusting the volume of the water flow. Gate valves are among the most commonly used valves in plumbing applications. Gate valves control water flow by raising or lowering an internal gate by use of a twist-type handle located at the top of the valve. Gate valves should never be used to control the volume of flow. They are designed to be fully open (allowing full flow) or fully closed (stopping the flow entirely). Using them to adjust water flow can wear out these valves. Gate valves are very reliable for closing off the water supply, and they are commonly used as shutoff valves on main and branch water supply lines. Gate valves are mostly used with larger pipe diameters (from 2" to the largest pipelines) since they are less complex to construct in large sizes.