Gate Valve Vs. Ball Valve [Sep 15,2015]
Valves are used to control the flow of gases, liquids and granular solids. They come in many types, sizes, materials, pressure and temperature ratings, and means of actuation. Gate valves and ball valves are two distinct members of the valve family, and are generally used for two different types of flow control.
Gate valves have a flat closure element that slides in and out of the media stream to open or close the valve. In the bronze-body gate valves that are frequently used in commercial and residential applications, a bronze disc moves up and down to open and close the valve. The valve is designed so the brass valve stem remains at the same height relative to the valve as the disc moves. A Teflon packing held in place by a threaded bonnet prevents leaks around the stem. Manual valves are actuated by turning a cast-iron handwheel.
Ball valves have a spherical closure element with a round or other-shaped hole in it. Aligning the hole with the flow opens the valve, and placing the solid outside of the ball in the flow shuts the valve. The ball rests on a valve seat, and the stem is inserted into the top of the ball. Packing and washers around the stem prevent leakage. A handle for manual actuation is attached to the stem. Stops keep the handle from rotating more than 90 degrees.