Casella CEL Software for the Microdust dust monitor User Manual

Page 22

Allow a few seconds for auto-ranging and for the reading to stabilise.
If the reading does not stabilise, rapidly squeeze the bulb a further

5 or 6 times and try again.

Once the reading is stable, press

The instrument will now set the reading to zero, ±1 digit.
If the reading is not within ±1 digit of zero, wait a few seconds then

press

again until it is.

When it is not possible for the instrument to zero itself on the

0 - 2.5 mg/m

range, a Contamination Warning message will be

displayed and a higher range selected. The 0 - 25 mg/m

range will

then become the lowest useable range until the probe is cleaned.

However, for accuracy and stability it is recommended that factory

cleaning take place.

Once the instrument has been set to zero, ensure that the rubber cap

is re-fitted to the purge inlet.

Select Set Span from the Calibration menu, so that the factory

calibrated span can be checked.
The basic span (or sensitivity*) of the instrument and probe is set

at the factory using ISO (Fine 12103-1 A2) calibration dust.

Enter

Note*:

All light scattering instruments can have some sensitivity to a particulates

refractive index, size, shape and colour. The MicroDust pro uses a narrow

forward scattering angle to minimise these effects, but for optimum

calibration to a specific dust type, gravimetric calibration may be required.

This is described under calibration for a specific dust type in Section 2.3.2.

Purge Bellows

Calibration

Filter

00023

Figure 12: Inserting the Calibration Filter

Page 22 of 60

Operation

MICRODUST pro Aerosol Monitoring System &

WINDUST pro Application Software - Handbook