How to Size a Compressed Air Dryer for Your Facility
A compressed air system is only as good as the air that comes out of it. You can have the best compressor on the market, but if your air is wet, inconsistent, or overloaded with moisture, it’s going to cause problems — from corroded piping to product defects to ruined tools.
That’s why sizing your air dryer correctly matters. It’s one of the most important decisions you can make for air quality and long-term system reliability.
At Industrial Air Services, we help facilities across Nashville, Knoxville, and Chattanooga choose and size air dryers that can handle Tennessee’s hot, humid climate. Here’s what you need to know before selecting one for your facility.
1. Start With Your Compressor’s Actual Output — Not the Nameplate
Dryers are sized based on CFM, not horsepower.
But here’s the catch: many people size a dryer based on the compressor’s horsepower rating or a generic chart, which doesn’t give you the true air volume.
What you need to know is the actual delivered CFM of your compressor at your operating pressure.
For example:
A 25 HP rotary screw may produce around 100 CFM
A 50 HP rotary screw may produce around 200 CFM
Dryers should always be sized equal to or larger than your compressor’s CFM output.
2. Understand the Operating Conditions (This Is Where Many Plants Get It Wrong)
Dryer performance changes depending on:
Ambient temperature
Inlet air temperature
Operating pressure
Humidity levels
These conditions affect how much moisture needs to be removed — and Tennessee’s climate is tougher than most.
A dryer rated for 100 CFM at 100°F inlet temperature may only handle 70–80 CFM if your compressor room is 110°F in July.
You should never buy a dryer without considering “real-world” temperature and humidity.
3. Oversizing a Dryer Is Usually Better Than Undersizing
If you’re between sizes, go bigger.
Undersized dryers:
Allow moisture through
Overload filters
Trigger corrosion
Cause rust and water contamination
Lead to higher maintenance costs
Properly sized (or slightly oversized) dryers run cooler, last longer, and deliver more consistent dew point.
4. Know the Difference Between Refrigerated and Desiccant Dryers
Most facilities use one of these two types:
Refrigerated Dryer
Good for most industrial applications
Produces a dew point around 35°F–50°F
Affordable and easy to maintain
Great for general manufacturing, machine shops, automotive, packaging, and typical compressed air use.
Desiccant Dryer
Needed for very dry air
Produces -40°F dew point or lower
Ideal for food, pharmaceutical, electronics, and sensitive processes
Hot, humid climates like Tennessee often push refrigerated dryers to their limits in summer — which is where desiccant systems or hybrid setups shine.
5. Consider the Pressure Drop Across Your Dryer
A dryer might be rated for 100 CFM, but if it causes a big pressure drop, your tools will feel sluggish.
Pressure drop should ideally be:
Less than 5 PSI for refrigerated dryers
Less than 10 PSI for desiccant dryers
The lower the pressure drop, the more efficient your system will be.
6. Add Additional Capacity If You Have Peak Demand or Expansion Plans
If your system experiences:
Sudden bursts of air use
Multiple shifts
Seasonal demand
Future expansions
Then sizing the dryer to your current CFM won’t be enough.
You need to size for your peak load, not your average load.
Otherwise, your dryer will run maxed out — especially in summer.
7. Wet Tanks Matter Too — They Help Your Dryer Work Better
A properly sized wet receiver tank (before the dryer) gives moisture time to condense before the air enters the dryer. This reduces the dryer’s workload and improves system performance.
Most dryers work better — and last longer — when paired with generous storage on the wet side.
8. Don’t Forget to Size Filtration Properly
Filters must be sized so they never restrict airflow into the dryer. Undersized or clogged filters can choke the dryer and cause:
High dew point
Pressure drop
Premature dryer failure
Your filtration and drying systems must be matched to your CFM and climate.
9. Tennessee Humidity Requires Heavier-Duty Dryers
Summers here can push refrigerated dryers to their absolute limit.
If your plant struggles with water during June–August, chances are your dryer is:
Undersized
Overloaded
Operating in a hot room
Not draining properly
Or simply worn out
Many Tennessee facilities benefit from:
Oversizing their refrigerated dryer
Switching to a desiccant dryer
Installing combination drying systems
Improving ventilation in compressor rooms
Moisture control is non-negotiable in our climate.
10. Get a Professional Sizing Assessment
Every facility is different, and dryer sizing depends on:
CFM
Pressure
Ambient temperature
Dew point requirements
Number of shifts
Seasonal humidity
Future expansion plans
At Industrial Air Services, we measure your actual air demand and environmental conditions so you get the right-sized dryer the first time.
Dry Air = Better Tools, Better Products, and Fewer Headaches
Sizing a dryer is one of the most important steps in maintaining clean, reliable compressed air. When the dryer is matched to your compressor and climate, everything downstream runs smoother — from tools to automation to product quality.
If you’re seeing moisture in lines or filters clogging too quickly, your dryer may not be sized correctly. We can help diagnose the issue and recommend the right solution for your system.
Industrial Air Services proudly serves Nashville, Knoxville, and Chattanooga, offering dryer sizing, installation, maintenance, and full moisture-control solutions.
📍 138 Bain Drive • LaVergne, TN 37086
📞 (615) 641-3100
🌐 www.industrialairservice.com
