2-12 AEROTRAK™ Portable Airborne Particle Counter
Performing a Zero Check
A zero check should be performed according to application
requirements. It should also be performed before conducting any
important testing or certification.
To Perform a Zero Check
1. Turn on the instrument and wait until the main menu
appears.
2. Unscrew the Isokinetic inlet if attached. The zero check cannot
be performed when the isokinetic inlet is attached to the
instrument.
3. Screw the zero filter assembly on to the threaded inlet located
on the top of the instrument.
4. Press the button and allow the instrument to purge for
5 minutes.
5. After the 5-minute purge, continue to sample. In accordance
with JIS standards, there should be no more than 1 particle
counted at any size in 5 minutes. Sample for 15 minutes. If 0
count observed, the instrument passes less than 1 particle per
5 minutes at a 95% confidence level; otherwise sample for
longer time for better statistics. Use ISO21501-4 Annex D to
calculate the false count rate at 95% confidence level for zero
count sampling times greater than 15 minutes.
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