Patent ID: 8500089

Claim:
A method of operating an on-off valve comprising steps of: closing one of two openings of a valve body by use of a seal member provided in a closure element located within the valve body, the valve body being provided within an evacuation pipe connected between a process chamber and an evacuation apparatus that evacuates the process chamber of a process gas or an active species, wherein the two openings allow the process chamber and the evacuation apparatus to be in pressure communication with each other; moving the closure element by use of a linear motion driver that linearly moves the closure element, so that the seal member is moved away from the one of the two openings, thereby allowing the two openings to be in pressure communication with each other; and positioning the closure element into a retreat portion provided in an surface of the valve body by use of the linear motion driver and a pivotal motion driver adapted to pivot the closure element between a first position corresponding to the one of the two openings and a second position corresponding to the retreat portion, so that the seal member is closed inside a protection seal member provided in the closure element to surround the seal member, thereby preventing the seal member from being directly exposed to the process gas or the active species from the process chamber, while the protection seal member contacts the retreat portion.