Vaisala HMT120 User Manual

Page 54

User's Guide _______________________________________________________________________

52 ___________________________________________________________________ M211244EN-B

NOTE

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 off

and the red indicator LED begins to blink slowly (800ms cycle time) to

indicate T calibration state. Now you can continue following the

instructions from step 7 onwards.
If one-point calibration is done at more than 50 %RH, a gain adjustment

is done instead of an offset adjustment.

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 off

and the red indicator LED begins to blink slowly (800ms cycle

time).

HMT120 transmitter is now in T calibration state. Analog output

and optional display will still follow the actual measured T value.

NOTE

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 off and the

transmitter returns to normal mode. The calibration procedure is now

finished.

Insert the probe into a known reference temperature (if HMK15

Humidity Calibrator is not used) and let the temperature reading

stabilize.

NOTE

Do not touch the adjustment buttons before the conditions have

stabilized.

Using the - and + buttons, make the temperature offset adjustment

by making sure the I

out

current is correct (you have to press either -

or + at least once even if the value is correct) and press the ADJ

button. The red indicator LED begins to blink faster (400ms cycle

time).

NOTE

If you do not wish to perform the two-point T adjustment at this time,

press the ADJ button one more time. The red indicator LED is turned

off and the transmitter returns to normal mode. The calibration

procedure is now finished.

10. Insert the probe into another reference temperature.