Vaisala HMP230 - Manual (Page 61)

HMP230 SERIES
M210225en-B User's Guide
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7.1.1.2. With display/keypad commands
• Make sure that the sensors of the transmitter and the reference in-
strument are close to each other. Allow enough time for the sensor
heads to stabilize to the measurement conditions.
Disconnect the security lock jumper!
• Select Cali in the main menu and then RH cal; select Not changed
and then one-point offset correction RH 1 point cal. Change the
humidity reading with the arrow keys to correspond to the reference
value and acknowledge it with ENT; pressing an arrow once changes
the reading by 0.05 %RH.
7.1.1.3. With LED commands
• Make sure that the sensors of the transmitter and the reference in-
strument are close to each other. Allow enough time for the sensor
heads to stabilize to the measurement conditions.
Disconnect the security lock jumper!
• Connect an ammeter/voltmeter to the analogue outputs (connector
X2); if the outputs are already connected e.g. to a process computer
and you do not want to disconnect them, the current output can be
measured at separate test points located next to connector X15 (see
Chapter 8.5). Give command ¡¡¡l (see Chapter 6.2). At the first
calibration point the LED on the left flashes; adjust the humidity point
(offset) with the arrow switches to the reference value. One push of a
switch changes the output by 0.05 %RH; the change of the output
voltage or current depends on the output scaling. Press ENT switch.
The second LED from left starts flashing; press ENT again.
7.1.2. Two point calibration procedure
A two-point humidity calibration should be performed in stable conditions
using saturated salt solutions as references.
NOTE
If the sensor has been changed, the calibration has to be
done according to the instructions in Chapter 7.1.3.