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What Is a Compressed Air Dryer and How Does It Work?
A compressed air dryer removes moisture from compressed air before it travels through your system and reaches downstream equipment.
Moisture is naturally present in the atmospheric air drawn into every air compressor. When that air is compressed, its temperature rises and it carries water vapour into the compressed air system.
As the compressed air cools, some of that water vapour condenses into liquid water.
Without effective moisture management, this water can make its way into pipework, pneumatic equipment and production processes.
Why does compressed air contain water?
All atmospheric air contains some level of water vapour. How much depends on conditions such as temperature and relative humidity.
Your compressor draws this moisture in along with the surrounding air. Compression concentrates the water vapour along with the air itself.
After compression, the hot compressed air begins to cool. As its temperature drops, its ability to hold water vapour also falls and condensation starts to form.
This is why moisture is a normal part of producing compressed air rather than necessarily a sign that something is wrong with your compressor.
The challenge is managing it effectively.
What does a compressed air dryer do?
Separators and drains can remove liquid condensate that has already formed. A compressed air dryer deals with the moisture that remains as water vapour in the compressed air.
The dryer reduces the amount of water vapour in the air before it continues through the distribution system.
This helps reduce the risk of moisture causing problems such as:
- Corrosion inside compressed air pipework
- Water reaching pneumatic tools and equipment
- Reduced equipment reliability
- Problems with processes or finished products
- Additional maintenance requirements
- Moisture accumulating further downstream
The level of drying required depends on the application and the air quality your equipment or process needs.
What is dew point?
Dew point is an important term when discussing compressed air dryers.
Put simply, the dew point is the temperature at which water vapour begins to condense into liquid water.
A lower pressure dew point means the compressed air contains less water vapour.
For many general industrial applications, a refrigerated dryer can provide an appropriate level of moisture removal. Applications requiring much drier compressed air may need a different type of air treatment, such as a desiccant dryer.
The right option depends on your application, operating conditions and required air quality.
How does a refrigerated compressed air dryer work?
Refrigerated dryers are commonly used in workshops, manufacturing facilities and other general industrial compressed air systems.
They work by cooling the compressed air. As the air temperature falls, water vapour condenses into liquid water.
The dryer then separates and drains this condensate before reheating the dried compressed air and sending it downstream.
This process provides a consistent way to reduce moisture without requiring extremely low dew points.
Why is dryer sizing important?
A dryer needs to handle the actual conditions of your compressed air system.
Airflow is one consideration, but it is not the only one. Inlet air temperature, ambient temperature and operating pressure can all affect dryer performance.
This becomes particularly important during warmer conditions. Higher temperatures and humidity can increase the moisture load entering your compressed air system and place additional demand on the dryer.
A dryer that is incorrectly sized or operating outside its intended conditions may struggle to achieve the required dew point.
Does every compressed air system need the same type of dryer?
No. The right air treatment depends on what you use the compressed air for.
A general workshop may have very different air quality requirements from a food production facility, specialist manufacturing process or other application where very dry air is required.
The complete system also needs to be considered. Dryers work alongside equipment such as filters, separators, drains and air receivers to manage compressed air quality and condensate.
Rather than selecting a dryer based on compressor size alone, it is important to consider the application and the conditions in which the system operates.
Looking for a compressed air dryer?
Nessco Pressure Systems supplies, installs and services compressed air dryers for customers across Perth and regional WA.
Our team can assess your compressor, airflow requirements, operating conditions and application to help determine the right dryer and air treatment for your system.
If you are installing a new dryer, replacing an existing unit or experiencing moisture problems in your compressed air system, call our team on 1300 290 638 or contact us online.
