Operation
6. Conduct a preflow calibration on the DustTrak monitor using the same
kind of sample media you will sample with. Now, attach the sample
media you intend to sample with and start sampling aerosol for the
desired time. After the desired run time, stop the sampling. Remove the
filter from the DustTrak monitor and follow your laboratory’s criteria for
filter post weight. Conduct a post-flow calibration with the same sample
media done with the pre-flow calibration and determine if these flow
calibrations are within ±5% of each other. If they are, use the following to
calculate the actual flow rate for the DustTrak monitor. The laboratory will
need the following information to calculate mass concentration in mg/m
3
:
Total sample time in minutes.
Flow rate—flow rate of the DustTrak monitor used for gravimetric
analysis is only
2
/3 the total flow since
1
/3 of the flow is used as
sheath flow.
Total liters of air sampled = total sample time x flow rate.
7. Using this information the laboratory can determine the concentration
using the following formula:
The flow rate used for gravimetric analysis is only
2
/3 the total
flow since
1
/3 of the flow is used as sheath flow.
8. For instructions on how to calibrate the DustTrak monitor using this data,
see section below on “Determining the Calibration Factor for a Specific
Aerosol”.
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