Vaisala HMP228 - Manual (Page 31)

HMP228
M210282en-A Operating Manual
25
4.4.1 Calibration procedure after sensor change
Humidity calibration should be performed in stable conditions using saturated
salt solutions as a reference.
Disconnect the security lock jumper!
4.4.1.1 Using serial commands
•
Leave the calibrator and the transmitter for at least 4 hours in the
same space so that their temperatures have time to equalize. Remove
the filter cap on the transmitter.
•
Insert the sensor head into the calibration hole of the LiCl chamber of
the humidity calibrator.
•
Wait for 30 minutes.
•
Give command FCRH <cr>, enter the first point value and press <cr>:
>FCRH <cr>
RH: 11.9 Ref1 ? yy.y <cr>
Press any key when ready...
•
The stabilization of the sensor to the reference humidity can be
monitored by giving c <cr>:
RH: 11.9 Ref1 ? c <cr>
RH: 11.5 Ref1 ? c <cr>
RH: 11.5 Ref1 ? 11.3 <cr>
Press any key when ready...
•
Insert the sensor head into the calibration hole of the NaCl chamber of
the humidity calibrator.
•
Wait for 30 minutes.
•
Press any key, enter the second point value and press <cr>:
RH: 75.5 Ref2 ? yy.y <cr>
•
The stabilization of the sensor can be monitored by entering c <cr>
instead of the reference value.
4.4.1.2 Using display/keypad commands
•
Leave the calibrator and the transmitter for at least 4 hours in the
same space so that their temperatures have time to equalize. Remove
the filter cap on the transmitter.
•
Insert the sensor head into the calibration hole of the LiCl chamber of
the humidity calibrator.
•
Wait for 30 minutes.