Vaisala hmt120 - Page 56

3. The transmitter is now in RH calibration state. Analog output and optional display will still
follow the actual measured RH value.
If you do not wish to perform the RH adjustment at this time, press the ADJ
button one more time. The green indicator LED turns o and the red
indicator LED begins to blink slowly (800ms cycle time) to indicate T
calibration state. To calibrate T, follow the instructions starting from step 7.
4. Remove the filter and insert the probe into a measurement hole of the dry end reference
chamber (for example, LiCl: 11 % RH) to do the low humidity oset adjustment.
Do not touch the adjustment buttons before the conditions have stabilized.
This takes approximately 30 minutes.
5. Press either the - or + button at least once, make sure that the I
out
current is correct,
adjust using the - and + buttons if needed, and press the ADJ button again. The green
indicator LED begins to blink faster (400ms cycle time).
If you do not wish to perform the two-point RH adjustment at this time, press
the ADJ button one more time. The green indicator LED turns o and the red
indicator LED begins to blink slowly (800ms cycle time) to indicate T
calibration state. To calibrate T, follow the instructions starting from step 7.
If one-point calibration is done at more than 50% RH, a gain adjustment is
done instead of an oset adjustment.
6. Insert the probe into the high end reference chamber (for example, NaCl: 75 % RH
chamber in the humidity calibrator HMK15) and do the high humidity gain adjustment by
using the - and + buttons to make sure the I
out
current is correct (you have to press either
- or + at least once even if the value is correct). To
finish the RH calibration, press the ADJ
button. The green LED is now turned
o and the red indicator LED begins to blink slowly
(800ms cycle time).
7. The transmitter is now in T calibration state. Analog output and optional display will still
follow the actual measured T value.
If you do not wish to perform the T adjustment at this time, press ADJ button
one more time. The red indicator LED is turned o and the transmitter
returns to normal mode. The calibration procedure is now finished.
HMT120 User Guide M211244EN-C
54