Panasonic PT-DZ12000U Operating Instructions Manual page 129

The air stream is then directed to a catalyst and heater
section where the elemental tritium is converted into tritium
oxide. From there the tritium oxide (which was elemental
tritium just before) is drawn through another set of collection
vials identical to the first set. The first set of vials contains the
tritium oxide from the original sample while the second set of
vials contains the elemental tritium which was converted to
the oxide form. When the contents of the vials are analyzed
a measurement of elemental tritium and tritium oxide can be
derived.
G. Impactors
Impactors are used to collect aerosols, either solid or liquid
particles.
An air pump pulls air through a opening small enough to
increase the velocity of the air stream to a level such that
large particles in the air cannot deviate from their straight
flight and therefore "impact" on a plate. Smaller particles can
go around the impactor plate because they have less kinetic
energy than the larger particles. Multiple impactor plates in
series and with higher and higher air velocities separate the
particles in distinct size ranges.
The cascade impactor and the Andersen sampler are
examples of impactor particle collection techniques.
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