3 Things to Know if You Use Desiccant Dryers


If you don’t work in an industry that deals with compressed air regularly, you’re not likely to know what a desiccant air dryer is. Desiccant air dryers remove moisture from compressed air and serve a crucial purpose, as the excess humidity that’s in the air can cause pipes to freeze and increase equipment degradation costs. Desiccant air dryers are tools that remove this water vapor at 4 to 6 times the cost of refrigerated, dried air, but resultantly feature a dew point rating of -40 on average, making them perfect for sensitive processes and instrumentation. If you use these regularly, here are some things you should know that can help to improve the efficiency or utility of desiccant dryers (and save you money in the long run).

  • The purge can continue even when the compressor is off

If you operate your desiccant dryer on a fixed cycle without any dew point control and the compressor you’re drying turns off and stops the air flowing through the dryer, it’s not uncommon for the purge to keep going. This purge will be fed from other system compressors, with a flow that lets the purge continue without interruption. If the desiccant is regenerated, a dryer that’s uncontrolled in this manner will continue to consume purge air and waste a lot of compressed air even though that air isn’t flowing through it. This can have huge effects on the efficiency of the dryer and should be put right to avoid extreme waste.

  • If your plant is hugely inefficient, check the dryer

If your plant has just had an audit and it reported tremendously inefficient use of compressed air, everybody is likely to think that the culprit is a leak or unwarranted drainage. This confusion is typically caused by an air dryer being misused or uncontrolled due to the purge continuing when the compressor is off. For this reason, desiccant air dryers can be the biggest use of compressed air in the whole plant if the responsible members of staff aren’t experienced enough. It could be that your dryer isn’t appropriate for your operation, which is why it’s important to source it from somebody that can analyze your needs and make recommendations informed from experience, the policy of companies like Super-Dry Systems.

  • Watch your purge flows – they can change

Purge flow adjustment is often manually operated at a specific part of the dryer cycle – it’s an important part of the process. This manual adjustment can be as simple as repositioning a ball valve in response to a gauge’s pressure reading. The ball valve typically becomes misadjusted over time, leading to poor calibration. The gravity of a poorly calibrated ball valve becomes more obvious if you compare it to a control valve. This can lead to purge flows that are far higher than the dryer rating and lead to wasteful flow that’s rarely detected. A good way to get around this is by testing regularly.

These three lessons can save any industrial operation a lot of money with simple solutions. Electricity inefficiency is often less expensive than compressed air inefficiency, which has the potential to spiral out of control if desiccators are left uncontrolled.


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