BAM 1020-9800 Manual Rev W.docx
Page 35
down onto the swab with its spring pressure. Use your thumb to rotate the nozzle while
keeping the swab in place. A few rotations should clean the nozzle lip.
4. Repeat the nozzle cleaning until the swabs come out clean, then inspect the nozzle lip
and vane again, looking for any burrs which may cause tape damage.
Nozzle and Vane Cleaning, and Disassembled View
The figure below shows the difference between good and bad filter tape spots. The tape on
the left is from a properly operated BAM 1020 with a clean nozzle and vane. The dust spots
have crisp edges, are perfectly round, and are evenly distributed.
The tape on the right is from a unit which has a leak. A spot of debris has built up on the
vane, and is punching a pin-hole at the edge of each spot. These holes can allow beta
particles to get through unattenuated which can lead to erroneous concentration
measurements
. The spots also show a “halo” effect due to air leaking in around the edge
because the nozzle is not sealing correctly. These faults are easily corrected and prevented
by keeping the nozzle and vane clean.
BAM 1020 hourly filter tape spots
Vane
Nozzle Lip
Cotton
Applicator