Abstract

A personnel air lock has a transfer chamber that is separated from an atmospheric region by an outside door and is separated from a containment region by an inside door. A single drive shaft couples a motor and three clutch-operable hand wheels to the doors to sequentially open and close one door and then the other. Each door is opened and closed through a door actuator linkage that is coupled to the drive shaft through a respective dual clutch and a respective clutch-actuating mechanism. One door-opening clutch is engaged as a lead screw nut moves through an active range along a timing lead screw, while another door-opening clutch is disengaged as an associated lead screw nut moves through an inactive range along another timing lead screw, so that only one of the doors is coupled to the drive shaft at a time. Each lead screw nut forms part of a slide indicator for indicating the operating position of its associated door. An air lock with this door sequencing mechanism is particularly useful in providing ingress and egress for a nuclear containment vessel.