Vaisala HMK15 - Manual (Page 29)

Chapter 4 ________________ Instructions for the Calibration of Humidity Instruments
VAISALA _________________________________________________________ 27
transportation temperature is below +18 °C, the LiCl salt
chamber should be transported separately to keep the
solution warm.
- When the calibrator is at the calibration site, remove
transit covers and fasten chamber covers on salt
chambers. Close the holes with plugs.
NOTE The plugs have three steps each of which is suitable for a
certain hole diameter: the first step for the 12 mm, the
second step for the 13.5 mm and the third step for the
18.5 mm hole.
- Clean the transit covers with a damp cloth and press them
on vacant chamber holders.
- Take the thermometer off the holder, turn the sleeve the
other way round and perform the calibration according to
section Calibration on page 23.
In on-site calibrations it is important to allow enough time
for the calibrator and probe temperatures to stabilize.
Depending on the temperature differences between the
transportation and the calibration site or between the probe
removed from the process and the calibration site, a two
point calibration takes about 0.5 … 2 hours. If there are
several frequently calibrated instruments at the same site,
knowing the stabilization times is useful.