Vaisala HMT360 - Manual (Page 67)

Chapter 6 __________________________________________________ Calibration and Adjustment
VAISALA_______________________________________________________________________ 65
Relative Humidity Adjustment
Automatic Two-Point Adjustment (Only
HMT360 with Display)
The automatic adjustment procedure is a user friendly way to adjust the
HMT360 with salt solutions; you do not have to feed the reference values
to the HMT360. The transmitter displays the accurate value based on the
measured temperature and the Greenspan table stored into the transmitter
memory. The display chart of the adjustment procedure is presented in
Figure 26 on page 66 .
1. Set the internal DIP switch Calibration Enabled/Disabled to
position ON and select RH calibration by using switches 3 and 4 (see
section
DIP Switch Functions on page 45 ).
2. Remove the filter and insert the probe into a measurement hole of the
LiCl salt chamber in the humidity calibrator. Acknowledge by
pressing button E. Alternatively select the 0.1 (humidity in nitrogen)
with buttons Up and Dn. Acknowledge with button E.
3. You must now wait for the measured reading to stabilize (10 ... 15
min). When the transmitter detects that the reading is stable, it
automatically stores the correction. When the text "Auto" is displayed
on the screen, continue with the next step.
4. Insert the probe into a measurement hole of the NaCl salt chamber in
the humidity calibrator. Acknowledge by pressing button E.
Alternatively you can select K
2
SO
4
value with buttons Up and Dn.
5. You must again wait for the measured reading to stabilize (10 ... 15
min). When the transmitter detects that the reading is stable, it
automatically stores the correction. The text "Cal Pass" is displayed
after the adjustment is performed.
NOTE Remember to restore the DIP switch settings.