| Problem |
| Possible cause |
| Corrective action |
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| Process heaters are faulty. |
| Check for open heaters. Replace |
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| if required. | |
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| Replace. | |
| Loss or reduction of process air |
| controller faulty. |
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| Make sure that plant personnel | |
| temperature. |
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| Process temperature was |
| are aware of the proper | |
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| adjusted in error by plant |
| temperature set point. Post an |
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| personnel. |
| appropriate sign next to the |
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| controller. |
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| Process heaters are faulty. |
| Replace. |
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| Desiccant beds are |
| Replace desiccant. |
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| contaminated. |
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| Drying systems are designed for |
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| Material being dried differs |
| the material which was |
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| originally specified. Different | |
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| from material specified at the |
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| materials may need a longer | |
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| time of purchase. |
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Loss or reduction in drying |
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| residence time or a different | ||
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| drying temperature. | ||
capacity. |
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| Break in flex hose to/from |
| Inspect for air leaks; replace as | ||
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| drying hopper. |
| needed. |
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| Airflow valve sticking or failing |
| Check for proper operation of |
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| valve actuators. Repair or | |
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| to shift. |
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| replace if necessary. | |
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| Blower fins filled with dust or |
| Remove blower side plate, |
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| clean baffles, replace. | |
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| contaminants. |
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| Replace filter elements. | |
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| Insufficient power to PLC |
| Check power supply and power |
| PLC Regeneration Bed LED |
| (Power LED is off). |
| wiring to PLC. |
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| Faulty PLC (PLC Power light is |
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| |
| indicators both off. |
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| Replace PLC. | |
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| on, Run light is off, and/or Error |
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| light is on). |
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| Regenerating bed cooldown. |
| None. |
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| Blower Input indicator is off. |
| Verify that blower contactor is |
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| on. Check input wiring to PLC. | |
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| PLC Regeneration Heater |
| Process air in |
| None. |
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| condition. |
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| Left/Right output indicators both |
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| |
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| Insufficient power to PLC |
| Check power supply and power | |
| off. |
| (Power light is off). |
| wiring to PLC. |
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| Faulty PLC (PLC Power light is |
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| on, Run light is off, and/or Error |
| Replace PLC. |
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| light is on). |
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Dehumidifying Dryers | Chapter 6: Troubleshooting | 49 of 59 |