DOC-0171 Rev G-9
2 7
© 2017 DROPLET MEASUREMENT TECHNOLOGIES
8.0
Calibrating the Instrument with Aerosol
Black Carbon
The recommended material for the SP2 calibration is Aquadag. This is an aqueous suspension of
colloidal graphite, with particle size less than 0.5 micron. At this time there are no known mono-
dispersed black carbon particles available for calibration of the SP2.
8.1 Required Equipment
Aerosol generator and an aerosol classifier that will provide particles in the 50-500 nm size range.
8.2 Calibration Procedure
To calibrate the instrument, follow the steps listed below. Figure 19 shows the typical setup for the
SP2 calibration using a DMA.
1.
Start the SP2 and the DMA. Take approximately 10 data points, with nominal particle size
between 80 nm to 500 nm. Generally two data files are taken at each setting.
2.
Shut off the DMA and the SP2.
3.
Process the data files and analyze the histograms generated for each of the particle sizes.
Depending on the DMA used, several peaks with particles of charge 1, 2, 3, and on up can
be seen. To avoid confusion, it is recommended that the first data analysis be conducted
with mid-range size particles, as the charge 1 aerosols will be seen clearly.
4.
Calculate the particle mass for the each of the particle sizes and plot particle mass vs.
maximum peak height. This should be a polynomial function. The parameters of this
function will form the calibration of the SP2. See the Probe Analysis Package for Igor (PAPI)
Manual (DOC-0232) or contact DMT for details.
Figure 19: Schematic Diagram for SP2 Calibration with DMA
