Vaisala HMP42 - Manual (Page 18)

HMI41 AND HMP42
Operating Manual
M210317EN-A
14
Table 5.2 Greenspan’s calibration table
°C
LiCl NaCl K2SO4
0 * 75.5 98.8
5 * 75.7 98.5
10 * 75.7 98.2
15 * 75.6 97.9
20 11.3 75.5 97.6
25 11.3 75.3 97.3
30 11.3 75.1 97.0
35 11.3 74.9 96.7
40 11.2 74.7 96.4
45 11.2 74.5 96.1
50 11.1 74.4 95.8
* If the LiCl solution is used or stored in temperatures below +18
°C, its equilibrium
humidity changes permanently
As the D (dry) and W (wet) adjustments may affect each other, check again
the humidity reading in the LiCl salt chamber: insert the probe into the
calibration hole and wait until the reading stabilizes. If necessary, repeat the
adjustments in both the LiCl and the NaCl (K
2
SO
4
) salt chambers until the
reading is correct.
5.3 Calibration with HMI41 software commands
Calibration can also be done with the HMI41 software commands by entering
the corrections in the indicator memory with pushbuttons. If only one probe is
being used, the HMI41 software calibration is useful. However, when several
probes are in use, it is recommended that calibration is done by adjusting the
probe potentiometers. Note that when the sensor head set is changed,
calibration must always be done by adjusting the potentiometers and it is
recommended that the HMI41 is reverted to factory settings by selecting
default calibration.
NOTE
If the factory calibration of the HMI41 is changed, the
correction data refers to the calibrated probe only.
Therefore, if you change the probe, always revert this
data to factory settings by selecting default calibration,
or perform a new calibration with the new probe.