A ball valve is one of the most widely used types of valves nowadays. The ball valves almost totally replaced the poppet valves which used to be very common in numerous applications. The basic element of the valve is a ball with a through bore – a fluid passage, placed in the valve body lined with sealing material. The ball is rotated by the stem which is also sealed. The 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 opening.
The body of the industrial ball valves is usually made of brass or stainless steel. The ball comes in chromium-plated brass or stainless steel. Typically the ball is sealed with PTFE (teflon) or RTFE (teflon reinforced with a filler e.g. fibreglass reinforced). The stem is sealed with NBR, Viton or PTFE. The valve end connections are usually with BSP thread or flanges. Working pressure of the industrial ball valves reaches several tens of bar.
Distinct types of the ball valves comprise 3-way and 4-way valves with three and four connections accordingly. The properly bored ball (for 3-way valves in T boring or L boring arrangement) allows for switching the direction of the flow in the installation.
The industrial ball valves cover such applications as: water, air, fuel installations, all sorts of gaseous and liquid media, steam, chemical installations – in all branches of industry.
For various types of high pressure ball valves see HYDRAULICS AND HIGH PRESSURE section and INSTRUMENTATION section. For ball valves with push-in fittings see PNEUMATICS section.