The FM-9-ABGN uses a standard filter in TA's unique quick change, with no leak holder to trap any airborne particulates. The filter is under constant surveillance via a thin window GM pancake detector.
Air is drawn by a regulated pump through a three-foot inlet hose and exhausted via a flow meter through another three-foot hose. These may be extended to allow monitoring of hoods, glove boxes, stacks, etc.
Time is recorded by a computer wired into the pump circuit.
The unit is completely self-contained and portable. Complete with a box of 100 filters.