The plastic drying system is more efficient when if the air going through the dryer is below 150 degrees Fahrenheit. If the plastic pallets in the hopper must be heated well above this temperature, the air entering the desiccant chamber must be cooled, so that it doesn't exceed 150 degrees Fahrenheit. To cool the air, an after-cooler also called a heat exchanger can be used. The after-cooler works like a radiator, water is circulated through coolant passages. The hot air flows through these passages and the coolant remove the heat from the air. Some desiccant drying systems may be equipped with a volatile trap. These volatile traps are used when the plastic being dried gives off volatiles. These volatiles are picked up by the air and are not trapped by the regular filters. If they are allowed to get to the desiccant bed, they condense on the surface, clogging the pours. This shortens the life of the desiccant bed. With use, the desiccant bed becomes saturated with moisture and needs to be regenerated. Regeneration uses a separated regeneration blower and heater. The processed air is drowned in, heated from 500-600 degrees Fahrenheit and blowing through the desiccant bed. The high temperature dries off the moisture trapped in the desiccant. This regeneration air is vented out of the process. Once the moisture is driven off, the regenerated bed needs to be cool before it can begin to absorb moisture once again.