5128A
Operators Manual
22
Calibrate UUTs
The subsequent sections explain how to do calibrations on humidity probes or
UUTs.
Recommended Calibration Sequences
These recommendations ensure fast, repeatable calibrations of humidity
sensors:
1. Do lower-relative humidity calibrations first and ramp up to the higher-
humidity levels on each subsequent calibration step.
2. Do lower-temperature calibration points first to minimize the probability of
water vapor condensing inside the chamber.
3. In general, best practice is to start at the lowest dew point and then move up
in dew point during a calibration procedure.
Note
When the dew point of the Product chamber is greater than the
ambient temperature, condensation can form on or near the
chamber door or on the UUT. If condensation forms anywhere in the
chamber, the relative humidity inside the chamber is unknown.
Condensation must always be removed from inside the chamber
before calibrations are performed. See
Remove Condensation
.
Remove Condensation
To remove condensation:
1. Turn off the Product, unplug the mains power cord, and remove the chamber
door.
2. Carefully inspect the mixing insert, chamber door, and UUT.
3. Remove the mixing insert to check the outer chamber for condensation.
4. Wipe off all condensation and moisture with a clean paper towel.
5. If condensation is present on the UUT, wipe the outer surfaces with a clean
paper towel. Do not touch the humidity sensing element.
6. Re-install the mixing insert, re-attach the door, plug in the mains power cord,
and turn on the Product. Heat the chamber to 40
°
C and relative humidity to
10 % for approximately 10 minutes to ensure proper performance.
