Relative Humidity Adjustment. Vaisala HUMICAP HMT330 SERIES, HMT330

Chapter 7 ___________________________________________________ Calibration and Adjustment

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).

1. Carry out the chemical purge (if available).

LiCl reference

2.

Press the ADJ button (see Figure 77 on page 156) on the

motherboard 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 probes of HMT334,

HMT335, HMT337 and HMT338.

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 button

LiCl~11% 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 probes of HMT334, HMT335, HMT337 and

HMT338.

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 button NaCl 75 % to adjust the 75 %RH condition. After adjustment transmitter returns to normal operation mode (indicator

LED is unlit).

VAISALA _______________________________________________________________________ 157