Vaisala Calibration of Series HMDW6070 and HMP140 Transmitter with HMI41 - Manual (Page 19)

HMI41 Calibration Option
19116ZZ-U218en-1.1 Operating Manual
1996-08-29 15
3.2 Humidity calibration
When performing the humidity calibration of the HMD/W60 transmitters,
make sure that the calibration cable is connected to the RH test connector
(Figures 3.2 and 3.3).
After having connected the cable, turn the HMI41 on with the ON/OFF button
and wait until the following text appears on the display:
RH
T
This message remains on the display for about 5 seconds. Press no button
when this text is displayed and the HMI41 will automatically go on to
calibration; a text similar to the following appears:
RH %
Numbers on the first line indicate the relative humidity measured by the
transmitter, and numbers on the second line indicate the RH measured by the
HMI41 reference probe. If you wish, you can now adjust the transmitter:
•
Wait until the readings have stabilized and adjust the calibration
potentiometers (Figures 3.2 - 3.4) until the readings on the first and
the second line are the same. It is recommended to use the offset
potentiometer if the RH is <65 %RH and the gain potentiometer if the
RH is >65 %RH.
•
After having completed the calibration, press MODE if you wish to
perform a temperature calibration (see next page), or ON/OFF
(disconnect the cable).
If you press the HOLD button in the first RH calibration mode, you will go on
to the second RH calibration mode which is an alternative for the first one. A
text similar to the following is displayed:
RH %