Vaisala HMK15 - Manual (Page 9)

Chapter 2 _____________________________________________Product Overview
VAISALA __________________________________________________________ 7
CHAPTER 2
PRODUCT OVERVIEW
Introduction to Vaisala Humidity Calibrator
HMK15
General
The HMK15 humidity calibrator has been developed for
calibration and checking of humidity probes and
transmitters. The functioning of the calibrator is based on
the fact that certain salt solutions generate a certain relative
humidity in the air above them.
The four holes in the chamber cover are designed for
Vaisala probes and transmitters with 12 mm, 13.5 mm (2
holes) and 18.5 mm diameters.
The salt solutions suitable for the HMK15 calibrator are for
example lithium chloride LiCl (11 %RH), magnesium
chloride MgCl
2
(33 %RH), sodium chloride NaCl (75 %RH)
and potassium sulphate K
2
SO
4
(97 %RH).
In calibration, the sensor head is inserted into a salt chamber
containing a saturated salt solution. The probe/transmitter
reading is then adjusted to the correct value, that is to the
humidity that the specific salt solution generates at that
particular temperature.