Ball valves are one of the most widely used types of valves today. They have almost completely displaced poppet valves in a great number of applications. The basic element of the valve is a ball with a through bore (fluid passage), placed in a valve body lined with sealing material. The ball is rotated by a stem which is also sealed. Standard ball valves act as shut-off valves and should not be used in any other way, especially as control valves, unless they are equipped with a pneumatically, hydraulically or electrically operated valve positioners, which adjust the degree of opening.
The body of industrial ball valves is usually made of brass or stainless steel. The ball comes in chromium-plated brass or stainless steel. The ball is usually sealed with PTFE (Teflon) or RTFE (Teflon reinforced with a filler e.g. fibreglass). Stem packing materials are NBR, Viton or PTFE. The end connections are BSP threads or flanges. The working pressure of the industrial ball valves reaches several tens of bar.
A separate type of ball valve is 3-way and 4-way valve with three and four connections respectively. The ball, bored through accordingly (for 3-way valves in T or L configuration) allows for switching the direction of flow in the system.
The industrial ball valves are used in systems conveying water, air, fuel, all sorts of gaseous and liquid media, steam, chemicals – in all industries.
For high pressure ball valves see HIGH PRESSURE section and INSTRUMENTATION section. For ball valves with push-in fittings see PNEUMATICS section.