TSI Instruments DustTrak 8520, Operation And Service Manual

Page: 42 / 89

Chapter 3 32
The D
UST
T
RAK
monitor has several features to aid in obtaining good
accuracy for a particular aerosol.
•
The D
UST
T
RAK
monitor’s custom calibration factor can be changed
through the instrument keypad. All future readings from the D
UST
T
RAK
monitor will correspond to a specific aerosol until the calibration factor
is changed back to the factory setting.
•
Custom calibration factors can be stored in a table and downloaded to
the D
UST
T
RAK
monitor using the T
RAK
P
RO
Data Analysis Software. All
future measurements will correspond to a specific aerosol until the
calibration factor is changed back to the factory setting.
•
A single set of logged data can be converted to data calibrated to a
specific aerosol with the use of the T
RAK
P
RO
software. This conversion
can be done by knowing either the true mass concentration for the
logged data or the calibration factor for the aerosol. Future
measurements will continue to be read and logged with the original
calibration factor (normally 1.0) and will not be converted
automatically.
All of these options require that you determine a true mass concentration
(e.g., gravimetric analysis) for the aerosol you want to measure. The true
mass concentration is used to calculate the custom calibration factor for that
aerosol. Once you have a custom calibration factor, you can reuse it each
time you make measurements in the same or similar aerosol environment.
Determining the Calibration Factor for a Specific Aerosol
The D
UST
T
RAK
monitor is factory calibrated to the respirable fraction of
standard ISO 12103-1, A1 test dust. The D
UST
T
RAK
monitor can be easily
calibrated to any arbitrary aerosol by adjusting the custom calibration factor.
The D
UST
T
RAK
monitor’s custom calibration factor is assigned the value of
1.00 for the standard ISO test dust. This procedure describes how to
determine the calibration factor for a specific aerosol. Using a value of 1.00
will always revert back to the factory calibration.
To determine a new calibration factor you need some way of accurately
measuring the concentration of aerosol, hereafter referred to as the reference
instrument. A gravimetric analysis is often the best choice, though it is
limited to nonvolatile aerosols.
To make an accurate calibration you must simultaneously measure the
aerosol concentration with the D
UST
T
RAK
monitor and your reference
instrument.
1. Zero the D
UST
T
RAK
monitor as described in the Maintenance chapter.