A ball valve is a valve with a spherical disc, the part of the ball valve which controls the flow through it. The sphere has a hole, or port, through the middle so that when the port is in line with both ends of the valve, flow will occur. When the valve is closed, the hole is perpendicular to the ends of the steel ball valve, and flow is blocked. The handle or lever will be inline with the port position letting you "see" the valve's position. The cryogenic ball valve, along with the butterfly valve and plug valve, are part of the family of quarter turn valves.
Ball valves are durable and usually work to achieve perfect shutoff even after years of disuse. They are therefore an excellent choice for shutoff applications (and are often preferred to trunnion ball valve and floating ball valve for this purpose). They do not offer the fine control that may be necessary in throttling applications but are sometimes used for this purpose.
top entry ball valve are used extensively in industry because they are very versatile, supporting pressures up to 700 bars and temperatures up to 200°C. Sizes typically range from 0.5 cm to 30 cm. They are easy to repair and operate.
The body of pneumatic ball valve may be made of metal, plastic or metal with a ceramic center. The ball is often chrome plated to make it more durable.
There are five general body styles of ball valves: single body, three piece body, split body, top entry, and welded. The difference is based on how the pieces of the trunnion mounted ball valve—especially the casing that contains the ball itself—are manufactured and assembled. The valve operation is the same in each case.