Abstract: A gas diverter includes at least one port circumscribed by a port seat, and a valve subassembly for selectively obstructing the port. The valve subassembly comprises: (a) an actuation arm; (b) a disk coupled to the arm, and (c) an actuator for selectively causing the disk to be urged against said port seat to obstruct said port. In operation, the disk deforms elastically as it is urged against the port seat.