Chapter 7 ___________________________________________________Calibration and adjustment
VAISALA______________________________________________________________________ 169
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). The three
buttons needed for the adjustment are located on the motherboard, at the
upper left corner of the transmitter.
1. Carry out the chemical purge (if available).
LiCl reference
2. Press the ADJ button (see Figure 74 on page 164) to open the
adjustment mode. The indicator LED starts flashing.
3. 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 PTU307 probe.
4. 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).
5. When the indicator LED is lit continuously press the LiCl~11% button
to adjust the 11 %RH condition. After adjustment transmitter
returns to normal operation mode (indicator LED is unlit).
NaCl reference
6. When adjusting in the second reference 75 %RH, press the ADJ
button to open the adjustment mode. The indicator LED starts
flashing.
7. 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 PTU307 probe.
8. 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).
9. Press the NaCl~75% button to adjust the 75 %RH condition. After
adjustment transmitter returns to normal operation mode (indicator
LED is unlit).
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