How to remove moisture from compressed air?
22 October 2025
Compressed air is one of the most widely used utilities in industry — but it comes with a hidden challenge: moisture. No matter the region or climate, atmospheric air always contains humidity. During compression, much of the moisture condenses into liquid form, leading to equipment malfunctions, production issues, and higher energy consumption.
In this article, we’ll explore how to remove moisture from air in compressed air systems, why it matters for long-term reliability, and what solutions are available. From cooling and separation to advanced drying technologies, you’ll see the options that facilities worldwide rely on to keep their systems efficient, compliant, and cost-effective.
Why moisture in compressed air is a problem
At first glance, a little condensation might not seem like a big deal. But moisture in compressed air can cause serious issues. Here’s what it can lead to:
- Blocked control lines: Water can interfere with sensors and valves, causing instruments to malfunction.
- Tool damage: Moisture washes away lubrication, leading to faster wear and tear on air tools.
- Pressure surges: Sudden bursts of water, known as “water hammer,” can create shock waves that damage pipes and equipment.
- Product contamination: In industries like food, pharma, or electronics, even small amounts of water can spoil products.
- Process disruption: Water in the air stream can directly affect production quality and reliability.
When air leaves a compressor, it’s hot and fully saturated with moisture. As it travels through the system and cools — especially in colder areas or outdoor pipe runs — that vapor turns into liquid water. Filters and separators can capture liquid moisture droplets, but they’re ineffective against water vapor. To fully protect the system, a dryer is essential to eliminate vapor before it condenses.
What dryer do I need for my compressor?
Different ways to remove moisture from air in compressors
The good news is that there are proven ways to control humidity in compressed air. The right solution depends on your application, air quality requirements, and operating environment. Below are the 5 most common approaches to compressed air moisture removal.
Cooling and separation
The hot, compressed air is cooled, which allows a large amount of water to condense. Once the water is condensed, it can then be separated from the air.
The most common separation methods used are:
Aftercooler (or heat exchanger) will cool down compressed air immediately after compression by using air or water to reduce the temperature, causing the moisture to condense. Best for removing bulk water before further drying
Refrigerant air dryers work like a refrigerator by chilling the compressed air and thus condensing water vapor, which is then removed. This is a general purpose method of drying in environments above freezing.
Over-compression
Over-compression involves the compression of air to a higher pressure than the intended working pressure. This increase in pressure will concentrate the moisture and it becomes liquid water, which can be easily removed. After separation, the air is allowed to expand to the working pressure so it can be used in the intended process. However, this method is only suitable for very small air flow rates, due to its high energy consumption.
Membrane drying
Membrane drying uses the process of selective permeation of the gas components to separate the water moisture from the air. Wet compressed air flows into a cylinder filled with thousands of hollow polymer fibers. These fibers are coated to allow water vapor to pass through so it can be purged, while retaining the dry air.
Absorption and adsorption drying
Absorption drying is a chemical process in which water vapor is bound to an absorption material such as sodium chloride or sulfuric acid. The absorption material can be either a solid or a liquid and is much less common than other drying methods.
Adsorption drying removes moisture from air using adsorption, a process in which water vapor adheres to the surface of a drying agent, known as a desiccant. The benefit of using adsorption over absorption is that the desiccant material can be regenerated once it is saturated with water. The typical pressure dew point (PDP) these dryers achieve is -40 °C/°F, making them suitable for providing very dry air.
How to prevent moisture build-up in compressed air systems
Knowing how to remove moisture from air compressors is important.
However, prevention is just as important. By designing and maintaining your system correctly, you can reduce the risk of moisture problems before they start.
1. Choose the right dryer for your needs
Every facility is different. A refrigerated dryer may be enough for a packaging plant, but a pharmaceutical cleanroom may require a desiccant dryer capable of reaching dew points below –40 °C. Matching your dryer to your dew point requirements avoids both under-drying (which leads to contamination) and over-drying (which wastes energy).
See our guide on choosing a dryer.
2. Size the system correctly
Undersized dryers and separators are one of the most common causes of moisture in compressed air. Always account for peak demand and potential expansion when specifying equipment.
3. Maintain condensate management
Automatic drains, separators, and filters must be serviced regularly. A blocked drain or saturated filter can quickly undo the best system design.
4. Follow ISO 8573-1 air quality standards
This international standard classifies compressed air purity, including moisture levels. By designing your system to meet the right class for your industry, you ensure compliance and protect sensitive processes.
Read more about ISO classes for compressed air quality.
5. Consider the local environment
Global facilities face different challenges:
- Humid regions (Southeast Asia, South America) → higher baseline moisture levels.
- Cold climates (Northern Europe, North America) → risk of freezing and ice blockages.
- Dusty or air-polluted regions → higher filtration needs alongside moisture removal.
By considering your environment as part of system design, you prevent costly downtime and improve reliability.
Find the right solution for your facility
Moisture in compressed air isn’t just inconvenient — it undermines system reliability, product quality, and energy efficiency. The right dryer and condensate management strategy make all the difference.
Atlas Copco provides a comprehensive portfolio of air dryers and treatment solutions tailored to your specific industry, operating conditions, and performance requirements. Backed by global expertise and supported locally, we ensure your compressed air systems remain dry, energy-efficient, and fully compliant.
Looking to improve compressed air moisture removal in your facility? Talk to our experts today.
Common questions
How is water vapor removed from the air?
Water vapor can be removed through cooling, separation, or drying technologies. For general use, refrigerated dryers are common, while desiccant dryers are preferred in industries that require extremely low dew points. Membrane and absorption methods also exist, though they are less common in large industrial facilities.
How to remove condensation from a pneumatic system?
Condensation is best managed through a combination of moisture separators, drains, and filters installed throughout the air system. Regular maintenance of these components is critical — even the best dryer can’t protect a system if condensate isn’t removed at every stage.
What’s the difference between compressed air humidity and condensation?
- Humidity is water vapor suspended in the air.
- Condensation happens when that vapor cools below its dew point and becomes liquid water.
Both must be managed to keep compressed air systems reliable.
How to remove moisture from an air compressor efficiently?
Efficiency depends on choosing the right technology for your needs. For example:
- Refrigerated dryers → low operating cost, moderate dew points.
- Desiccant dryers → higher energy use but essential for critical industries.
The key is to balance energy efficiency with air purity requirements, minimizing the total cost of ownership.
Do compressed air dryers reduce operating costs?
Yes. By protecting tools, reducing leaks, preventing product spoilage, and lowering unplanned downtime. A properly sized dryer pays for itself many times over during the system’s lifecycle.
