AEC WD 350 through WD3000 Dehumidifying Dryers - Manual (Page 52)

Caution!
Use caution when working inside the control cabinet,
as high voltage is present.
Do not attempt to make any adjustments to the
components on the dew point control board.
To check the dew point system control board:
1. Shut off the dryer, then remove the sensor cable from the sensor hex nut adapter.
2. Connect the cable to the plug on the rear of the simulator.
3. Turn on the dryer, then turn the rotary knob on the simulator to each position and note the
readings on the dew point meter on the dryer control panel. The readings should
correspond within a degree or two (1º to 2º) across the entire range.
4. If the readings agree, the control board is working properly and you should replace the
dew point sensor. If the readings do not agree, replace the control board and run the test
again to rule out the possibility of a bad sensor.
5. When you have finished testing, shut down the dryer and re-connect the control cable to
the sensor adapter.
7-4 Symptoms of Worn Desiccant
The moisture absorption capacity of desiccant used in your AEC/Whitlock dryer degrades after
an indefinite period of time. Useful life depends on variables such as material moisture content,
plasticizer vapors in the return air, and number of regeneration cycles.
Note: AEC recommends replacing desiccant every three (3) years if you run your dryer an
average of eight (8) hours per day, five (5) days per week. You should replace desiccant
more often if you run your dryer for longer time periods.
Your AEC/Whitlock dryer may need new desiccant if it exhibits any of the following symptoms:
• Plastic material is not being dried sufficiently (high scrap/reject rate).
• Air temperature at the top of the regenerating desiccant bed rapidly climbs to 350°F
(177ºC) or more shortly after the start of regeneration, even though a saturated bed has just
started heating.
• The process air dew point, measured with a portable dew point monitor, is higher than
-10°F (-23ºC) throughout the process drying cycle.
• Smoke or dust blows out of the process air outlet.
• Noticeable amounts of desiccant in the beds is a medium-brown color or darker.
WDMR and WDFR Series Dehumidifying Dryers Page 51