Page 5-2
Airnet II Particle Sensor Operations Manual
Chapter 5
Maintenance and Performance Checks
To check the air flowrate:
1.
Disconnect all sample tubing and sample probes.
2.
Connect the unrestricted test flow meter to the sample inlet fitting.
3.
Run a sample and monitor the flow meter readings. The measured flow should be
the following:
•
Models 301, 501, 501A – 0.085 to 0.115 CFM (± 5 %)
•
Models 510, 510XR – 0.085 to 1.15 CFM (± 5 %)
Background Count Check
Perform this check upon installation or when suspected contamination or noise-
induced counts may be causing inaccurate data. Background counts can be caused by
power line transients, cosmic ray particles, or RFI or EMI noise counts. Externally
induced counts are the exception; the only way to verify externally induced counts is to
perform this procedure.
To perform this procedure, you will need an absolute filter rated at less than 0.2 micron
(effective to 0.1 micron in air).
To perform a background count check:
1.
Locate the Airnet II particle sensor to where it will normally be used.
2.
Remove the isokinetic sample horn.
3.
Place the 0.2 micron absolute filter and inlet tubing adapter in series with the
sample inlet flow tube.
4.
Run six 10-minute samples.
5.
Verify that background count rates average less than ten counts per ten minutes
when using the specified filter.
6.
Return the instrument to normal operation by removing the filter from the sample
line.
