Does your regenerative dryer desiccant look like this?
Your company may rely on a regenerative desiccant dryer to keep their compressed air in the best-operating conditions for production. Most industrial users of compressed air are familiar with regenerative desiccant air dryers. These dryers are really the only choice when ultra-dry compressed air is required. Regenerative dryers provide line pressure dew points of -40°F and even -100°F. Standard dryers with capacities ranging from 50 SCFM to over 10,000 SCFM are common. Usually, these dryers are installed within or very close to the location of the air compressors.
Although these dryers are powerhouses for ultra-dry compressed air, the one thing that is not often spoken about is the desiccant that goes inside of them. Activated Alumina is an aluminum oxide bead with a highly porous structure and high surface area-to-mass ratio. Activated Alumina has various applications, including compressed air and gas drying. In compressed air and gas drying applications, activated Alumina will achieve dew points -40°F to -100°F, depending on the dryer design. In compressed air desiccant dryers, a 1/
8″ (2-5 mm) activated alumina bead is most commonly used. The 1/4″ (5-10 mm) activated alumina bead is typically used as a pre-bed for supporting large desiccant beds or as a buffer for silica gel beds. The 3/16″ (5-10 mm) bead is used when pressure drop and surface area requirements fall between the 1/8″ and 1/4″ material.
The service life expectancy for activated Alumina is 2-5 years. Why is this important? Because if your desiccant is contaminated, your dryer may not operate at its fullest. Does your desiccant appear brown, gray, or off-white in appearance? These colors indicate that they are contaminated, and the regenerative air dryer should have a complete desiccant change out.
Activated Alumina should be white and clean as pictured on top of the pile pictured here:
If your samples of desiccant still appear to be good, but you’re not achieving the dew point your expecting, you can send those samples to Van Air Systems for a free moisture capacity test. Just contact Angie for return authorization: or call 1-800-840-9906 ext 284.