Vaisala HMT120 - Manual (Page 52)

User's Guide _______________________________________________________________________
50 ___________________________________________________________________ M211244EN-B
Calibration and Adjustment
Calibrate and adjust the HMT120 using the push-buttons on the
motherboard, serial line commands (see section Calibration Commands
on page 33), or with portable humidity meters HM70 or HMI41.
A calibrator kit is needed for calibration against saturated salt solutions.
The HMK15 Humidity Calibrator and pre-measured certified salts are
available from Vaisala. For further information, please contact your
Vaisala representative.
Vaisala Service Centers also offer accredited calibrations for humidity
and temperature. See contact information on page 69.
It is also possible to remove the HMP110 probe and replace it with a new
one. The old probe can be adjusted using another HMT120 transmitter
body, if you have one available.
NOTE RH Field Calibration and Adjustment, as instructed in the following
pages, is restricted to a certain adjustment range to minimize the effects
of special circumstances, such as chemical contamination. In case the
probe is outside its adjustment/trim range due to, for example, chemical
exposure, the calibration cannot be completed. In this case, it is
recommended that you change the probe or contact Vaisala Services.
HMT120 Push-Button Calibration
1011-155
Figure 16 Adjustment Buttons
Calibration and adjustment of the HMT120 can be done by using the
adjustment buttons found at the transmitter. The two-point humidity
adjustment is carried out by using two relative humidity references: for
example saturated salt points 11 %RH (LiCl) and 75 %RH (NaCl). The
difference between the two humidity reference points must be at least