Desiccant

Desiccant is essential when it comes to maximizing the output of your compressed air system. While the concept of desiccant is pretty straightforward, it is helpful to know the different kinds and what is best for your air compressor. Below we take a look at the different types of desiccant including silica gel and activated alumina, and how they work.

What Is Desiccant and Why Do You Need It?

Desiccant is a collection of very small beads that are made up of a material that absorbs water and water vapor. The reason these beads are so small is so that they can move freely around the air compressor dryer, and to cover the widest possible surface area. Most of the time the biggest size of bead you will see is 3/8”. The reason you need desiccant in your air compressor is to dry out the compressed air that is being cooled by water as it moves through your compressor.

It is important to dry your compressed air using some sort of dryer with desiccant in it because compressed air with water vapor can damage the products you are using compressed air on. If you fill up a car tire with some water vapor, for example, that water could freeze to the inside lining of the tires. In the warmer months, it could become liquid and again damage the inside lining of your car’s tires, reducing the lifetime and reliability of your tires.

Activated Alumina vs Silica Gel

Activated Alumina

• Activated alumina is manufactured from aluminum hydroxide by dehydroxylating it in a way that produces a highly porous material. Used as a desiccant, it works by a process called adsorption. The water in the air actually sticks to the alumina itself in between the tiny passages as the air passes through them. The water molecules become trapped so that the air is dried out as it passes through the filter. This process is reversible. If the alumina desiccant is heated to 200°C, it will release the trapped water. This process is called regeneration.

Silica Gel

• Silica gel, when used as a desiccant, also works by utilizing adsorption. This process is reversible, just like activated alumina. If the silica gel desiccant is heated to 180°F, it will release the trapped water. This process is also called regeneration.
• The fact that silica gel desiccant can be regenerated at such low temperatures is both good and bad; it is good because generating heat of 180°F is fairly easy to do, Silica Gels can be baked in a kitchen oven and effectively be regenerated.  The downside to this is that in an actual application, such as in an air compressor, temperatures can reach well above 100°F which would cause the Silica Gel to partially regenerate and while doing so it would expel its moisture back into the free air volume being protected.  This dynamic is crucial to ensuring proper protection for sensitive fluid systems.  As temperatures increase, Silica Gel performance drops off drastically.
• One benefit of using silica gel over activated alumina is that the silica gel will change color when it is ready to be replaced. For someone using a larger compressor with more heated parts, activated alumina will be your best bet. For someone using an air compressor in a small business or personal setting, where the compressors do not get as large, silica gel will be the better option.

At www.Edmac.com, you can find many types of desiccant, including activated alumina and silica gel, from all of the major OEM brands. All of our own Edmac-branded air-ends meet or exceed OEM specifications and are competitively priced to save you money, while still delivering the performance you need. Our parts benefit your equipment by performing at the level of the manufacturer’s parts at a fraction of the cost.

We sell multiple brands and types of desiccant, and our Edmac Guarantee, which ensures you get fast shipping, excellent customer support, and high-quality performance products, backs each product we sell.

Feel free to browse our full collection of air compressor air-ends. If you have product or compressor-specific questions, please call our product specialist team at (800) 866-2959.