Abstract: To reduce invasion and adhesion of foreign matters into and onto the gating-member retreat room in the transition from the gate-open state to the gate-close state including retreat and on-shutting-movement of the gating-member. The shutter, being moved in the shuttering movement room, shuts the entrance aperture by making the shutter sealing contact with the stationary seal by such movement of the shutter itself when the gating-member is accommodated in the gating-member retreat room, and, also being moved in the shuttering movement room, shuts the entrance aperture by making the shutter sealing contact with the second gate seal by such movement of the shutter itself when the gating-member, being moved in the shuttering movement room, shuts the exhaust port by making the first gate seal contact with the stationary seal by such movement of the gating-member itself.

Abstract: To reduce invasion and adhesion of foreign matters into and onto the gating-member retreat room in the transition from the gate-open state to the gate-close state including retreat and on-shutting-movement of the gating-member. The shutter, being moved in the shuttering movement room, shuts the entrance aperture by making the shutter sealing contact with the stationary seal by such movement of the shutter itself when the gating-member is accommodated in the gating-member retreat room, and, also being moved in the shuttering movement room, shuts the entrance aperture by making the shutter sealing contact with the second gate seal by such movement of the shutter itself when the gating-member, being moved in the shuttering movement room, shuts the exhaust port by making the first gate seal contact with the stationary seal by such movement of the gating-member itself.