Dew point is one of those terms that gets thrown around a lot in compressed air conversations but it’s rarely understood properly. If your site relies on dry air for product quality, instrumentation, packaging, or preventing corrosion, dew point should matter to you. Here’s why...
Dew Point Explained
In simple terms, dew point is the temperature at which water vapour in the air will start to condense into liquid.
The lower the dew point, the drier the air.
So, when someone says their system has a “dew point of -40°C,” it means the air is so dry that moisture won’t start condensing until it’s cooled to -40°C. That’s typical for desiccant dryers in critical applications.
A “+3°C dew point” (which you’ll get from most refrigerated dryers) means moisture starts condensing as soon as the air cools below 3°C - which is fine for general plant air, but not always suitable for sensitive processes.
Why It Actually Matters
Most sites don’t monitor dew point directly. They assume the dryer is working and move on.
But here’s the problem:
A failing dryer won’t always trigger alarms
If the dew point creeps up to +10°C or higher, it might not trip out your dryer, but you’re still blowing wet air into the system.
Moisture builds up downstream
This causes corrosion in pipework, poor-quality end product, and damages pneumatic equipment.
You lose energy
Higher moisture levels mean pressure drops, more condensate removal, and less effective tools.
We See This All the Time
In our compressed air audits, we often install temperature and dew point loggers to confirm dryer performance. It’s not unusual to see:
Fridge dryers delivering +10 to +15°C dew point (instead of +3°C)
Desiccant dryers passing full flow through only one tower
Dryer bypasses left open, feeding raw air into production lines
And nobody knows because there’s no dew point sensor, or it’s never been checked.
What Should Your Dew Point Be?
Application Typical Required Dew Point:
General plant air (tools, blowguns) +3°C
Packaging / electronics -20°C to -40°C
Food, pharma, instrumentation -40°C or lower
If you're unsure what your process requires - or whether you're actually achieving it - it's worth checking.
How We Can Help
At Compressed Air Energy Solutions, we offer two routes to confirm dew point performance:
As part of a full system audit:
We install dew point loggers alongside flow and pressure monitoring to gather accurate, week-long data on your system.
This includes dew point measurement along with oil carryover and solid particulate analysis, ideal for sensitive or regulated environments.
Whether you want to spot performance drift or confirm your air meets ISO standards, we’ve got it covered.
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