COSA Xentaur Hygrocontrol Type 86 Ex - Manual (Page 17)

The solutions we supply for calibration create rel. humidities from 0 to
95%. We are using the following:
0% - drying granulate
10% - mixed LiCl and ZnCl2 solution
20, 35, 50, 65, 80, 95% - unsaturated LiCl solutions
The marked rel. humidities relate to a temperature of 22°C and do have a
temperature dependency. The accuracy of the solutions at 22°C is +/-
0.5%, they are not toxic and are not dangerous to the environment.
To assure the easiest handling and highest accuracy, the solutions are
enclosed in glass ampoules, which should be opened only before usage.
Opening is simplified by the weakened middle part of the ampoules. Once
opened the solutions may catch humidity from or give humidity to their
environment - so the time of usage is restricted and they should be used
for one calibration only.
3.2.1 General Notes about Calibration
Due to the temperature dependency of rel. humidity over salt solutions,
you should assure a constant temperature of 22°C with deviations of not
more than 1°C. Before a check or calibration of a probe is initiated, take
care for thermal equilibrium between probe, calibration chamber and
calibration solution. This can be done by placing the probe in an area free
from draughts, direct sunlight, radiators and any other factor that might
cause temperature fluctuations. Place the instrument on an insulating base
such as polystyrene and assure that the instrument, calibration chamber
and solutions are conditioned to the same temperature before starting the
calibration.
The cover of the probes housing should be closed during a
calibration - otherwise errors could occur. The cover of the
transmitter may be open to operate the code switch or jumper and
may stay open during the calibration.
Do not shut down the power supply during a calibration.
3.2.2 Mounting the Calibration Device
First remove the filter from the tip of the probe. The chamber may now be
screwed to the thread of the probe. The bottom of the chamber is
removeable and it is here that the textile pad and the solution are to be
placed. To avoid improper humidity values, always clean the bottom of the
chamber thoroughly, use new pads, and new solutions.
Ensure that the calibration chamber faces downwards, to avoid
direct contact of the solution with the sensor. Before inserting the
bottom into the chamber, unscrew the chamber slightly, to help
escaping air, when you close the chamber. Tighten the chamber
again after closing!
HYGROCONTROL Manual for Type 86 Ex Page
16