Vaisala HMT330 - Manual (Page 161)

Chapter 7 ___________________________________________________ Calibration and Adjustment
VAISALA _______________________________________________________________________ 159
Using Serial Line
Note that the difference between the two humidity references must be at
least 50 %RH.
1. Connect the HMT330 to a PC. See section Serial Line
Communication on page 79. Open a terminal program.
2. Carry out the chemical purge (if available).
3. Press the ADJ button.
4. Remove the filter from the probe and insert the probe into a
measurement hole of the dry end reference chamber (for example,
LiCl: 11 %RH in the humidity calibrator HMK15). Use the adapter
fitting for the probes of HMT334, HMT335, HMT337 and
HMT338.
5. Enter the CRH command and press ENTER.
>crh
6. Wait at least 30 minutes for the sensor to stabilize.
7. Type C and press ENTER a few times to check if the reading is
stabilized.
8. When the reading is stabilized, give the reference humidity after
the question mark and press ENTER.
>crh
RH : 11.25 Ref1 ? c
RH : 11.25 Ref1 ? c
RH : 11.25 Ref1 ? c
RH : 11.24 Ref1 ? c
RH : 11.24 Ref1 ? 11.3
Press any key when ready ...
9. Now the device is waiting for the high end reference. Insert the
probe into the measurement hole of the high end reference chamber
(for example, NaCl: 75 %RH chamber in the humidity calibrator
HMK15). Use the adapter fitting for the HMT334, HMT335,
HMT337 and HMT338 probes. Press any key when ready.
10. Let the probe stabilize for about 30 minutes. You can follow the
stabilization by typing C and pressing ENTER.