Ball valves offer straight-through, unimpeded flow with a minimal valve body footprint. Because of their unique design, ball valves are less sensitive than other vacuum valves to particulate contamination and, therefore, are especially useful in 'dirty' vacuum applications. For example, ball valves are almost always used to isolate scrubbers and traps downstream of the rough pumping system.
Principles of Operation and Construction: Ball valves are made of a body, stem, ball, and end caps. The ball is sealed within the body by end caps creating a vacuum tight central cavity. The valve is opened and closed by turning the stem 90° back and forth (1/4 turn). The sealing seat for the ball wipes the ball clean as it is opened and closed. This last features provides the "self-cleaning" action that makes this valve fairly robust to particle-rich effluent streams. Pneumatic actuators are available.