Vaisala HMT310 - Manual (Page 25)

Chapter 3 ________________________________________________________________ Installation
VAISALA ________________________________________________________________________ 25
Mounting the Probes
Do not unsolder and then again resolder the probe cable from the mother
board during installation; this may alter the humidity calibration of the
transmitter.
Beware of Temperature Differences
In humidity measurement and especially in calibration it is essential that
the temperature of the probe and the measuring environment is the same.
Even a small difference in temperature between the environment and the
probe causes an error. As the curve in Figure 6 below shows, if the
temperature is +20 °C and the relative humidity 100 %RH, a difference
of ±1 °C between the environment and the probe causes an error of
±6 %RH.
0507-036
Figure 6 Measurement Error at 100 %RH when Difference
Between Ambient and Sensor Temperature is 1 °C