Vaisala MMT330 - Manual (Page 143)

Chapter 7 ___________________________________________________ Calibration and Adjustment
VAISALA _______________________________________________________________________ 143
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Figure 70 Adjustment Menu
Table 30 Indicator Led Functions
Indicator Led Function Description
LED off adjustment locked
LED on adjustment available
LED blinking evenly measurement not stabilized
Relative Humidity Adjustment
Using Push Buttons
A simple push-button adjustment is carried out by using two relative
humidity references: 11 %RH (LiCl) and 75 %RH (NaCl).
LiCl reference
1. Press the ADJ button (see Figure 69 on page 142) on the
motherboard to open the adjustment mode. The indicator LED
starts flashing.
2. Remove the filter from the probe and insert the probe into a
measurement hole of the 11 %RH (LiCl) in the humidity calibrator
HMK15. Use the adapter fitting for the MMT332, MMT337 and
MMT338 probes.
3. Wait at least 30 minutes for the sensor to stabilize (the indicator
LED is lit continuously). Adjustment cannot be done if the
conditions are not stabilized (indicator LED is flashing).
4. When the indicator LED is lit continuously press the button
LiCl~11%
to adjust the 11 %RH condition. After adjustment transmitter
returns to normal operation mode (indicator LED is unlit).
NaCl reference
5. When adjusting in the second reference 75 %RH, press the ADJ
button to open the adjustment mode. The indicator LED starts
flashing.
6. Insert the probe into a measurement hole of the 75 %RH (NaCl)
reference chamber of the humidity calibrator HMK15. Use the
adapter fitting for the MMT332, MMT337 and MMT338 probes.