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No. 4
Aerosol Generator Recalibration
The aerosol generators ATI manufactures
employ Laskin nozzles to produce aerosol. The Laskin nozzles
are fabricated in strict accordance with Figure 4 of Naval
Research Laboratory (NRL) Report
#5929. These nozzles are then fitted into a Model III-A
configuration generator. As indicated by the NRL Report, the
aerosol produced in this configuration is sub-micron in size
and highly reproducible.
The NRL Report also states that if the nozzle
was configured with two rather than four jets, the airflow
through it and the amount of aerosol produced would be reduced
by half. Experience has shown that these nozzles will not
change significantly over their life time; however, they are
subject to clogging if the compressed air is not filtered.
If the jets of the nozzles become clogged the amount of aerosol
output is reduced. If unfiltered compressed air is used, the
nozzles will clog, causing the aerosol generator to produce
little or no aerosol.
Since these generators are mechanical in
nature they should not change throughout their life time.
Therefore, ATI does not recommend returning them for service
on a regular basis. However, if the nozzles become clogged,
the unit should be returned for service. This same philosophy
is also applicable to thermal aerosol generators, models TDA-5A
and TDA-5B, which use a thermal mass instead of Laskin Nozzles
to generate aerosol.
With ISO 9000 quality programs gaining widespread
acceptance customers may require a National Institute of Science
& Technology (NIST) traceable certification on a generator
pressure gauge. In some cases certifiers have been asked for
NIST traceable certification on the aerosol size distribution.
ATI can provide gauge calibration as well as aerosol size
distribution certification for additional fees. Please contact
one of ATI's customer service
representatives for current pricing.
The NSF will require NIST certification for
the generator gauge used when taking the NSF certification
practical exam. The exam will not be given without the certification.
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