How long desiccant last depends on several factors, including the type of dryer, application, and the level of maintenance provided. For instance, with proper maintenance of pre-filters, activated alumina desiccant can last up to 5 years in heatless dryers, but only 2 to 3 years in heat-regenerated dryers. (It's important to visually inspect the desiccant for discoloration and oil contamination to ensure it is functioning properly.)
To ensure the longevity of your desiccant, it's necessary to follow the manufacturer's recommended maintenance procedures, including regular inspections and replacement of the desiccant as needed. By taking proactive steps to prevent oil contamination and minimize exposure to heat, you can extend the lifespan of your desiccant and ensure that your air dryer is functioning properly for years to come.
Absorbent desiccants, such as Dry-O-Lite, 10BF, and SP (Special Purpose), actually absorb moisture and eventually dissolve. So, we recommend refilling the desiccant every 4 to 6 weeks. These tablets slowly dissolve at a rate relative to your inlet moisture content, temperature, pressure, and flow rate. We generally tell people they will need to top off every 4-6 weeks with an amount equal to about 1/3 of the overall desiccant bed. This would hold true for all 3 types of Absorbent Desiccants.
Adsorbent desiccants, such as activated alumina and silica gel, can last up to 3-5 years provided you maintain contaminant-free air entering the dryer. It is imperative to have a good single or dual-stage inlet filtration to remove any contaminants to prevent them from entering the regenerative dryer. If contaminants are allowed into the regenerative dryer, your desiccant will become contaminated as well and will no longer be able to function properly. If the desiccant bed becomes contaminated, you will need to replace the desiccant bed completely.
Factors affecting desiccant lifespan include operating conditions, the quality of compressed air being dried, the design and efficiency of the dryer system, and the specific desiccant material used. Different types of desiccants, such as molecular sieve, activated carbon, and clay desiccants, have their own lifespans and characteristics, so it's essential to follow the manufacturer's recommendations for replacement.
Regular monitoring of the desiccant's performance is important. Methods such as pressure drop measurements, moisture content analysis, and visual inspection can be used to assess the desiccant's condition. Additionally, it's important to maintain proper inlet filtration to remove contaminants from the compressed air before it reaches the desiccant dryer. This step helps prevent desiccant contamination and extends its lifespan.
Remember to consult the dryer system's manufacturer or refer to the specific product documentation for precise instructions on desiccant maintenance, replacement, and lifespan. Following these guidelines will ensure that your desiccant lasts as long as possible and that your dryer system operates efficiently.