Casella CEL Sampling heads for personal dust sampling - Manual (Page 12)

4 RESPIRABLE DUST HEADS
Respirable dust is the fraction of the total inhalable dust that enters the gas
exchange region of the lungs.
4.1 Higgins-Dewell Plastic
Cyclone (Part No. 116000B)
The plastic cyclone head is used for the respirable
fraction of dust. The original cyclone was developed
by Higgins and Dewell, at the British Cast Iron
Research Association (BCIRA), for use in sampling
quartz in fettling operations. The aim of the cyclone
is to separate the heavier particles from the smaller
and lighter ones. This is achieved by
“centrifugation”.
The diagram in Figure 8 indicates how the
lighter particles are drawn up through the cyclone,
while the larger, heavier particles fall down into the
grit pot.
The cyclone head
incorporates a 25 mm filter cassette
holder which should be weighed
complete. When the application
requires a larger filter, a 37 mm
cassette can be used.
Fit or replace the filter as
follows.
1.
Unscrew the retaining ring
and lift off the ring and outlet
body.
2. Lift out the cassette.
3. Separate the cassette.
Place the top half of the
cassette upside down so
that it resembles a shallow
bowl.
4. Rest the filter paper on top
of the support gauze inside
the top half.
5. Invert the lower part of the
cassette and clip it into place.
6. Operate at 2.2 litres/min.
Note that the particles caught in the
grit pot cannot be removed for
analysis.
Figure 8: The Cyclone Sampling Head
Casette
lower half
Body
Vortex
induced here
Air Flow In
- from flowmeter
Grit pot
02054
Casette
upper half
Screw cap
Air Flow Out - To PUMP
Filter
Filter support
(above filter
because flow
is upwards)
Respirable Dust Heads
Page 12 of 24
SAMPLING HEADS AND ACCESSORIES
Users Guide