Vaisala HMM213 - Manual (Page 32)

USER'S GUIDE____________________________________________________________________
Humidity Calibration
A one-point calibration can be done against an accurate transfer standard
in the field and a two-point calibration using saturated salt solutions in
controlled conditions (HMK15). You can also send the instrument to
Vaisala or a Vaisala representative for recalibration.
Humidity Calibration with Serial
Commands
Two-Point Calibration
CRH
With this command, the transmitters can be calibrated at two humidity
points against a reference.
An example of performing the two point calibration with the HMK15:
1. Leave the calibrator and the probe for at least 1 hour in the same
environment so that their temperatures have time to equalize.
2. Remove the sintered filter and insert the probe into the
measurement hole of the LiCl salt chamber in the humidity
calibrator.
3. Give the command CRH and the following text appears:
>CRH
RH : 12.00 Ref1 ?
4. Wait for 20 to 40 minutes. If the stabilization of the sensor to the
humidity in the calibrator needs to be monitored, the measurement
output can be repeated by at Ref1 and Ref2.
>CRH
RH : 12.00
Ref1 ?
RH : 11.70 Ref1 ?
RH : 11.50 Ref1 ?
...
5. Check the temperature and read the closest corresponding RH
value in the calibration table. Give the value and acknowledge it
with enter.
RH : 12.00 Ref1 ? 11.3
Press any key when ready ...
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