These types of valves rely on the rotary motion of the flow obstructer In most cases this rotation is limited to 90 degrees (one quarter-turn), however, there are valves that operate using a larger degree of rotation and have more than 2 positions that are used in regular operation. Valves that are truly quarter-turn are completely closed at 0Ëš and completely open at 90Ëš. Examples of quarter-turn valves are ball valves, plug valves, and butterfly valves.
