The refrigerant dryers use refrigerant gas to cool the compressed air. As a result, the water from the air condenses and can be removed. With this technique, we can reach max. 3°C. PDP. An adsorption dryer uses an adsorption material called “desiccant” in order to absorb and remove (by regeneration phase) the humidity from the compressed air. With this method, we can reach a PDP < 3°C. ( -40°C. or -70°C.). An adsorption dryer should also be used when the ambient temperature goes below freezing point to avoid ice building in pipes and applications.