Vaisala HMP240 User Manual
Page 50
HMP240
User's Guide
M210300en
48
6.1.3 Humidity calibration procedure after sensor change
Humidity calibration should be performed in stable conditions using saturated
salt solutions as a reference. If the transmitter has the re-gaining option, the
re-gaining has to be done manually before starting the calibration.
6.1.3.1
With 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 sensor head.
Disconnect the security lock jumper!
•
Insert the sensor head into the measurement hole of the
LiCl chamber.
•
Wait at least 20 minutes for the reading to stabilize.
•
Give command FCRH <cr>, enter the first point value and
press <cr>:
>FCRH <cr>
RH : xx.x Ref1 ? yy.y <cr>
Press any key when ready...
•
The stabilization of the sensor to the reference humidity
can be monitored by entering 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 measurement hole of the
NaCl chamber.
•
Wait at least 20 minutes for the reading to stabilize.
•
Press any key, enter the second point value and press <cr>.
RH : xx.x Ref2 ? yy.y <cr>
•
The stabilization of the sensor can be monitored by
entering c <cr>.
6.1.3.2
With 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 sensor head.
Disconnect the security lock jumper!