Vaisala Oyj Humidity and Temperature Transmitter HMT334

Loosen the filter by turning it counter-clockwise

Remove the filter from the probe

Install a new filter on the probe

Order new filters from Vaisala if needed

Connect HMT330 to a calibrated current/voltage meter

Press the ADJ button to open the ADJUSTMENT MENU

Select Adjust analog outputs, press ► button

Select the output to be adjusted

Measure the first analog output value with a multimeter and enter the value

Measure the second analog output value with a multimeter and enter the value

Press OK to return to the adjustment menu

Testing activates relays even if they are disabled.

Use the module push buttons to activate the relays. Press the REL 1 or REL 2 button to activate the corresponding relay.

Check if REL 1 button activates the relay (LED is lit)

Check if REL 2 button activates the relay (LED is lit)

Use the display/keypad to test the operation of relays.

Open the MAIN MENU by pressing any of the arrow buttons.

Select System, press the ►arrow button.

Select Diagnostics, press the ►arrow button.

Select Relay tests, press the ►arrow button.

Carry out the chemical purge (if available). LiCl reference.

Press the ADJ button on the motherboard to open the adjustment mode.

Remove the filter from the probe and insert the probe into a measurement hole of the 11 % RH (LiCl) in the humidity calibrator HMK15.

Wait at least 30 minutes for the sensor to stabilize.

Is the indicator LED lit continuously?

Press the button LiCl~11% to adjust the 11 % RH condition.

Press the ADJ button to open the adjustment mode for NaCl reference.

Insert the probe into a measurement hole of the 75 % RH (NaCl) reference chamber of the humidity calibrator HMK15.

Is the transmitter within the accuracy specifications?

Select the method for calibration and adjustment

Perform calibration using the selected method

Was the calibration successful?

Document the calibration results

Is further adjustment required?