5.Remove the restricted filter cartridge from the housing again. The alarm light should stay off when the process blower operates if the switch is adjusted correctly.
6.
7.Fine tune the switch setting so it consistently warns of a blocked filter and does not falsely indicate a blockage of a clean filter.
8.Remove the restriction from the filter element and
Checking the Dewpoint Control System
The Dewpoint Switch option on dryers depends on the proper operation of the dewpoint sensor and its control board. The dewpoint sensor is in the process air stream and is therefore susceptible to contamination.
Dewpoint sensor life is dependent on:
Air temperature and flow passing over the sensor.
The amount of fines [dust] in the process air.
The amount of plasticizer vapor in the process air.
The dryer operator should monitor the initial dewpoint sensor readings and establish a periodic replacement schedule as needed.
Caution! Do not attempt to check the continuity or resistance of a dewpoint sensor. The sensor will be destroyed.
If you suspect that the dewpoint readings on the dewpoint meter are incorrect, a dewpoint simulation calibrator is available from the manufacturer [part number A0549143]. This device simulates various dewpoint outputs. It can confirm proper operation of the dewpoint sensor and dewpoint system control board.
Use the following procedure to check the dewpoint sensor and dewpoint control board:
1.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 the rotary knob on the simulator to each position and note the readings on the dewpoint meter on the dryer's control panel. The readings should correspond within a degree or two across the entire range.
4.If the readings agree, the control board is OK. Dewpoint sensor replacement is recommended. If the readings do not agree, replace the control board and run the test again to rule out the possibility of a bad sensor.
Note: Do not attempt to make any adjustments to the components on the dewpoint control board.
5. When testing is finished,
Large Dehumidifying Dryers | Maintenance | 44 |