Vaisala HMP260 - Manual (Page 44)

HMP260 SERIES
Operating Manual
HMP260-U017en-1.5
38 1997-11-25
6. CALIBRATION
The HMP260 transmitters have been fully calibrated at the factory and there
should be no immediate need for recalibration. The transmitters should be
calibrated only if there is reason to believe that the adjustments of the
transmitters have changed. The adjustments of the temperature measurement
channel and the analogue outputs are particularly stable and in normal
circumstances there is no need to recalibrate them. Humidity calibration
should be performed at least once a year.
6.1 Humidity calibration
A two-point calibration can be done with the HMK11 or the HMK13B
Calibrator, or the instrument can be sent to Vaisala. We recommend
recalibration at least once a year. The instruments must be recalibrated every
time the HUMICAP humidity sensor is changed.
The covers of the calibration jars of the HMK11 and HMK13B Calibrator do
not have a hole for the Ø 13.5 mm sensor heads of the HMP260 transmitters;
therefore an adapter must be used when calibrating with the HMK11 or
HMK13B Calibrator. The adapters (part no. 16612 or 16611 respectively) can
be ordered from Vaisala or Vaisala representatives.
Calibration can be performed by giving the commands using the press
switches inside the housing (see Chapter 5.2 LED commands), through the
serial bus (Chapter 5.4 serial commands) or through the menus on the local
display (Chapter 5.3 display/keypad commands).
When LED commands are used and when the two analogue channels do not
output either relative humidity and/or temperature, relative humidity is cali-
brated on channel 1 and temperature is calibrated on channel 2. The calibra-
tion ranges are 0...100 %RH and -20...+80 °C. When the transmitters are
calibrated at two points, the points must be either 50 %RH or 50 °C apart from
each other.