NBC BLOWER
Honeywell LMB pioneered a very specific design with one main blower and a scavenge blower, both driven by a single motor.
The main blower is used to blow air within the crew compartment whereas the scavenge one cleans the NBC (cyclone) filter. In order to avoid "dirty" air coming from the scavenge fan to the main blower, there is a magnetic coupling between the motor and the scavenge fan which is totally "sealed".