Calibration
The calibration process is only for the dust sensor part of the DCES-DTRHF, the other sensors being already calibrated.
Calibration is not an easy process, for the dust sensor and since this sensor is a data centre environmental sensor it is designed to be very good at detecting any dust anomalies even if not calibrated*
Even if you correctly calibrated the dust sensor, you should expect
some variations because optical particle scattering is impacted by
relative humidity*, therefore if you need really precise measurements
at high frequency, you need to go for a commercial model with a regular
professional calibration service.
As said earlier, this sensor is aimed at data centre environmental
monitoring.
Calibration methodology
First of all, to achieve correct calibration you either need to put the
sensor in an environment containing a precise amount of dust particles
of a given size...
Or more easily you can go for relative calibration and calibrate the
dust sensor against a calibrated commercial sensor.