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Which compressed air dryer should you choose?
When choosing a compressed air dryer, it is important to select a solution that matches both your compressed air system and the application where the air will be used.
The two most common types of compressed air dryers are refrigerated dryers and desiccant dryers. But what is the difference, and when should you choose one over the other?
The most important factor to consider is the pressure dew point – in other words, how dry your compressed air needs to be.
Quick choice: Refrigerated dryer or desiccant dryer?
As a general rule:
Choose a refrigerated dryer if you need standard dry compressed air and a pressure dew point of around +3 °C is sufficient.
Choose a desiccant dryer if you require a very low pressure dew point, such as −20 °C or −40 °C, or if the compressed air will be used in low-temperature environments.
| Requirement | Recommended solution |
|---|---|
| General industrial compressed air | Refrigerated dryer |
| Pneumatic equipment and compressed air tools | Refrigerated dryer |
| Heated production environment | Refrigerated dryer |
| Low energy consumption and simple operation | Refrigerated dryer |
| Outdoor compressed air installation | Desiccant dryer may be relevant |
| Risk of freezing | Desiccant dryer |
| Very low pressure dew point | Desiccant dryer |
| Critical instrument and process air | Desiccant dryer |
What is a refrigerated dryer?
A refrigerated compressed air dryer removes moisture by cooling the compressed air. As the air is cooled, some of the water vapour condenses into liquid water, which is then separated and removed from the compressed air system.
The dried compressed air is then supplied to the rest of the compressed air installation.
A refrigerated dryer is a popular choice for standard industrial compressed air systems because it combines a relatively simple design with low operating costs.
When should you choose a refrigerated dryer?
A refrigerated dryer is typically the right choice when:
- the compressed air is used in a heated production environment
- you use compressed air for pneumatic equipment and tools
- there are no specific requirements for extremely dry compressed air
- a pressure dew point of around +3 °C is sufficient
- you want to keep both initial investment and operating costs low
Advantages of refrigerated dryers
- Lower purchase price
- Relatively low energy consumption
- Simple operation
- Limited maintenance requirements
- Suitable for most standard compressed air installations
In short: If you need standard dry compressed air, a refrigerated dryer is often the most economical solution.
What is a desiccant dryer?
A desiccant compressed air dryer uses a desiccant material to adsorb water vapour from compressed air.
The desiccant is continuously regenerated so that it can continue to remove moisture. This makes it possible to achieve a significantly lower pressure dew point than with a standard refrigerated dryer.
Desiccant dryers are therefore primarily used in applications where high levels of compressed air dryness are required.
When should you choose a desiccant dryer?
A desiccant dryer is relevant if:
- you require a pressure dew point below 0 °C
- the compressed air needs to be extremely dry
- the compressed air installation is exposed to freezing conditions
- the compressed air is used outdoors or in cold environments
- moisture can affect product quality
- you have critical processes or instrumentation
- there are strict requirements for compressed air quality
Depending on the type, desiccant dryers can achieve very low pressure dew points, such as −20 °C, −40 °C or lower.
Advantages of desiccant dryers
- Very low pressure dew point
- Excellent protection against condensation and freezing
- Suitable for critical processes
- Can provide extremely dry compressed air
The main disadvantage is typically a higher initial investment and higher operating and maintenance costs compared with a refrigerated dryer.
What is pressure dew point?
The pressure dew point is the temperature at which water vapour in compressed air begins to condense at the current pressure.
The lower the pressure dew point, the less moisture the compressed air contains.
It is therefore important not to automatically choose the lowest possible pressure dew point. The right solution is the dryer that meets the requirements of your installation without creating unnecessary operating costs.
Example
If your compressed air system requires a pressure dew point of around +3 °C, a refrigerated dryer will normally be the most suitable choice.
If your process requires a pressure dew point of −40 °C, you will typically need a desiccant dryer.
Refrigerated dryer vs. desiccant dryer
| Refrigerated dryer | Desiccant dryer | |
|---|---|---|
| Typical pressure dew point | Approx. +3 °C | Approx. −20 to −40 °C or lower |
| Drying performance | Good | Very high |
| Initial investment | Lower | Higher |
| Energy consumption | Lower | Higher |
| Maintenance | Limited | More extensive |
| Design | Simple | More complex |
| Freeze protection | Limited | Very good |
| General industrial compressed air | ✓ | |
| Very dry compressed air | ✓ | |
| Critical process air | ✓ |
How to choose the right compressed air dryer
1. Determine the required pressure dew point
Always start by determining which pressure dew point your machine or process requires.
Around +3 °C → Refrigerated dryer
Below 0 °C → Consider a desiccant dryer
−40 °C or lower → Desiccant dryer
2. Where will the compressed air be used?
Consider where the compressed air travels after leaving the compressor.
Is it:
- indoors?
- outdoors?
- in a heated room?
- in a cold production area?
- routed through pipes that may fall below 0 °C?
If the compressed air installation is exposed to low temperatures, the risk of condensation and freezing increases.
3. How important is moisture removal?
Moisture in compressed air can, among other things, lead to:
- corrosion in the piping system
- problems with valves and pneumatic components
- condensation in the compressed air system
- operational problems
- problems in sensitive production processes
The greater the potential consequences of moisture, the more important it is to choose the correct compressed air drying technology.
Sizing a compressed air dryer
The correct size of the compressed air dryer depends not only on the compressor’s nominal capacity.
When sizing a compressed air dryer, you should consider:
- Air flow in Nm³/h or m³/min
- Operating pressure
- Inlet temperature
- Ambient temperature
- Required pressure dew point
- Load profile
- Operating hours
A correctly sized dryer ensures that you achieve the required compressed air quality without unnecessarily high energy consumption or pressure loss.
Which compressed air dryer is right for you?
Refrigerated dryer – the economical choice
Choose a refrigerated dryer if you need reliable, dry compressed air for general industry, pneumatic equipment, tools and production.
View our range of refrigerated dryers →
Desiccant dryer – when the air needs to be extremely dry
Choose a desiccant dryer if you require a very low pressure dew point, freeze protection or particularly dry compressed air for critical processes.
View our range of desiccant dryers →
Frequently asked questions
When should I choose a refrigerated dryer?
A refrigerated dryer is typically the best choice for standard compressed air installations where a pressure dew point of around +3 °C is sufficient.
When should I choose a desiccant dryer?
You should consider a desiccant dryer when a pressure dew point below 0 °C is required, or when the compressed air needs to be extremely dry and protected against freezing.
Is a desiccant dryer better than a refrigerated dryer?
Not necessarily. A desiccant dryer can provide a lower pressure dew point, but it is typically more expensive to purchase and operate. If a refrigerated dryer meets the requirements of your application, it will often be the most economical solution.
What does pressure dew point mean?
The pressure dew point indicates the temperature at which water vapour in compressed air begins to condense at the current pressure. A lower pressure dew point generally means drier compressed air.
Can a refrigerated dryer be used outdoors?
It depends on the installation and temperature conditions. If the compressed air or piping system can be exposed to temperatures below the dryer’s pressure dew point, condensation or freezing may occur. In such installations, a desiccant dryer may be more suitable.
How do I size a compressed air dryer?
You should consider factors such as air flow, operating pressure, inlet temperature, ambient temperature and the required pressure dew point. Always use the manufacturer’s sizing data when making the final selection.
Get help choosing the right compressed air dryer
Are you unsure whether to choose a refrigerated dryer or a desiccant dryer?
Send us the following information:
• Compressor air flow • Operating pressure • Required pressure dew point • Application • Ambient temperature
We will help you find a compressed air dryer that suits your system and requirements.