Selecting an Air Dryer for Air Compressor. Important Questions to Consider.

Posted by Tyler on 04 25 2016

Picking the right compressed air dryer can be a daunting task.  You must carefully choose from a dizzying array of dryer types, sizes, features, options, and brands.  Here are some important questions you should ask as you noodle through this decision.

1. How dry do you need your compressed air to be?  Is liquid free good enough or do you need a particular dew point?  The answers to these questions depend on your application.  If you're running pneumatic equipment outdoors in Minnesota you'll need a much different level of dryness (i.e. dew point) than if you're painting cars in Burbank. 

2. What are your operating conditions?  Know the pressure, flow rate, and approximate air temperature at the point where you plan to install the dryer.  These variables are the basis for sizing most compressed air dryers (and filters).

3. Do you understand the cost of pressure drop?  Pressure drop is a hidden cost within an air system.  Your compressor gobbles up a lot of electrical energy to create air pressure.  Some of that pressure is lost while air flows through piping, fittings, tanks, filters, and dryers.  A cheap-o dryer and filter can easily cause 10 PSI of pressure differential or more.  You have to ask yourself, are you really saving money when investing in low cost air treatment equipment that quietly robs system pressure?  Definitely not!  A common rule of thumb is that each additional PSI of pressure increases electrical energy consumption by 2%.

Contact me to talk about your application.  I'll guide you to the right solution, even if it's not an item I sell.  In the meantime here's a cheat sheet showing the general features of different compressed air dryer types.

Refrigerated Deliquescent Desiccant
Regenerative Desiccant Non-regenerative Desiccant Membrane
Power Required Yes No Yes No No
Pressure Drop 3-5 PSI <1% of inlet 5 to 7 PSI <1%
Dew Point 39⁰F to 50⁰F 20⁰ F below inlet temp. -40⁰ F -40⁰ F -40⁰ F to 35⁰F
Indoor / Outdoor Indoor only Both Both Both Both
Initial Cost Low to moderate Low to moderate High Low Moderate
Operating Cost Low Low to moderate High High High
Purge Loss None None 15 to 20% None 15 to 20%
Maintenance Skill Semi-skilled Non-skilled Skilled Non-skilled Non-skilled
Effects of compressor oil Fouling of heat exchanger
Some discoloration of desiccant, normally not a problem Ruins desiccant Ruins desiccant Fouls membrane