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BA314001-en
6 Maintenance
Apart from routine zeroing and occasional range calibration, the instrument requires very little
maintenance. The only consumable items are the high-efficiency HEPA filters (internal and
external) used, respectively, to clean the airflow protecting the optical system lenses and to
remove particles from the sample stream before discharging to atmosphere.
6.1
Checking and Replacing the Rear Panel Filter
A high performance HEPA filter, manufactured to remove >99.9% of all particles down to
0.1micron size, is installed on the rear panel of the instrument.
Fig. 8: Rear Panel Filter
The filter cartridge should be examined for evidence of particle "breakthrough" on the surface of
the filter media (the white cylinder inside the clear casing).
The filter should be checked daily. Filtered sample flows from the inside to the outside of the
media. If black or dark brown discolouring is evident on the media surface, the element must be
replaced. The filter in the above picture has gone a long way past the point when it should have
been replaced!
To replace the media element, first unscrew and remove the clear plastic filter bowl. Then
unscrew and remove the black plastic media retainer, together with the media element. Remove
and replace the element with one of similar specification.
Replacement and reassembly are the opposite sequence to above. When installing the clear
plastic filter bowl, do not over-tighten the threads, as this may make subsequent removal
difficult. Sealing is effected by the O-ring on the cylindrical body, not by end contact, so do not
rotate the bowl further once resistance is felt. Occasionally lightly smear the O-ring with an
appropriate lubricant.
