21
to it. If the Sensor is to be calibrated outside the chamber,
remove the Sensor from its installed position.
2. Turn on the power. Allow at least 5 minutes for the system to
warm up. The Sensor and reference unit must be in a constant
temperature environment of 73
°
F/23
°
C,
±
5
°
F/3
°
C and humidity
environment for at least 30 minutes to obtain
humidity/temperature equilibrium prior to calibration.
3. Establish a required relative humidity level in the chamber.
4. Read the temperature and relative humidity. Compare the
reference unit reading with the level displayed on the
Dehumidifier Controller display. They should be within ±2% R.H.
of each other. If not, adjust the “1-point RH-calibration” control,
located through an access hole on the right-hand side of the
control unit as shown in Figure 3.2-4 until the correct reading is
obtained. A small blade screwdriver is required to perform this
adjustment.
Figure 3.2-4 Calibration adjust potentiometer
This completes calibration of the Model 5112 Dehumidifier
Controller.
Other calibration techniques include the use of wet bulb/dry bulb
and chilled plate measurement. Wet bulb/dry bulb instruments
should not be used in the test chamber because the wet bulb adds
humidity to the chamber making it extremely difficult to calibrate at
low humidity levels. However, there are wet bulb/dry bulb
calibrators with a small test cell for the sensor that can be used.
3.2.6 Troubleshooting
The Model 5112 is all solid state and should provide many years of
trouble-free service. If a problem with the system is suspected, it is
recommended that the fault be initially isolated to either the Sensor
or the Control Unit.
