High-performance compressed air treatment for clean, dry air: Moisture is a natural component in air. After compression, its content increases relative, forming condensate. Compressed air dryers effectively remove this moisture, preventing corrosion in downstream systems and ensuring product air quality.
Compressed air dryers lower the air’s dew point to prevent condensation, protect equipment from corrosion, and maintain consistent product quality across industrial processes.
Multiple types of compressed air dryers are available on the market. Understanding their operating principles will help in selecting the most suitable solution for specific applications.
What is the function of the air dryer?
The primary function of a compressed air dryer is to remove moisture from compressed air to prevent damage, inefficiency, and contamination in industrial systems. When air is compressed, its moisture content becomes concentrated, leading to condensation. If left untreated, this moisture can cause corrosion in pipelines, clogging of pneumatic tools, bacterial growth, and compromised product quality. For industries such as food processing, pharmaceuticals, electronics, and chemical production, uncontrolled moisture can lead to severe product defects and safety risks.
A compressed air dryer lowers the air’s dew point, ensuring that water vapor does not condense even when the air temperature decreases. By maintaining dry air, dryers extend the service life of equipment, reduce maintenance costs, and improve overall production efficiency. Refrigeration dryers, for example, use a cooling process to condense and remove water vapor, offering a reliable and economical solution for general industrial applications. Desiccant dryers, on the other hand, adsorb moisture at the molecular level, delivering extremely low dew points required in sensitive operations like electronics or medical production. In short, air dryers are critical to maintaining system integrity, reducing operational risks, and ensuring high-quality output across a wide range of industries.
Compressed air quality classes according to ISO 8573 1:2010
| ISO 8573-1:2010 Compressed Air Contaminants and Purity Classes | ||||||||
| Class | Particles | Water | Oil | |||||
| By particle size (Maximum number of particles per m³） |
By Mass | Vapor Pressure Dewpoint | Liquid | Liquid, Aerosol,&Vapor | ||||
| 0.10-0.5 μm | 0.5-1.0 μm | 1.0-5.0 μm | mg/m³ | ℃ | ℉ | g/m³ | mg/m³ | |
| 0 | As specified by the equipment user or supplier and more stringent than class 1 | |||||||
| 1 | 20,000 | 400 | 10 | – | ≤ -70 | ≤ -94 | – | <0.01 |
| 2 | 400,000 | 6,000 | 100 | – | ≤ -40 | ≤ -40 | – | <0.1 |
| 3 | – | 90,000 | 1,000 | – | ≤ -20 | ≤ -4 | – | <1 |
| 4 | – | – | 10,000 | – | ≤ +3 | ≤ +37 | – | <5 |
| 5 | – | – | 100,000 | – | ≤ +7 | ≤ +45 | – | – |
| 6 | – | – | – | 0-5 | ≤ +10 | ≤ +50 | – | – |
| 7 | – | – | – | 5-10 | – | – | ≤ 0.5 | – |
| 8 | – | – | – | – | – | – | 0.5-5 | – |
| 9 | – | – | – | – | – | – | 5-10 | – |
| X | – | – | – | >10 | – | – | >10 | >5 |
| Microblological Contaminants | Other Gaseous Contaminants | |||||||
| No purity classes are identified | No purity classes are identified Gases mentioned are: CO, CO2,SO2, NOX, Hydrocarbons |
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Desiccant air dryer working principle
Desiccant air dryers operate on the principle of adsorption, where moisture molecules adhere to the surface of an adsorbent material such as activated alumina or molecular sieves. The dryer system is typically designed with two towers: one actively drying compressed air while the other undergoes regeneration to remove accumulated moisture. The process alternates between the towers to provide continuous operation.
Two main types exist: heatless and heated desiccant dryers. Heatless models use a portion of the dried air at lower pressure to regenerate the desiccant, making them simple and reliable but less energy efficient. Heated desiccant dryers, by contrast, use external or internal heaters to drive moisture off the desiccant, reducing purge air loss and offering greater energy savings. These systems can achieve dew points as low as -40°C to -70°C, providing ultra-dry air suitable for industries like electronics, aerospace, and pharmaceuticals where even trace moisture is unacceptable. While highly effective, desiccant dryers typically involve higher capital costs, greater energy consumption, and increased maintenance requirements compared to refrigeration dryers. Nonetheless, their unmatched drying performance makes them indispensable for critical applications.
Refrigeration air dryer working principle
Refrigeration air dryers remove moisture by cooling compressed air to near-freezing temperatures, causing water vapor to condense into liquid. The condensate is then separated and drained, leaving behind dry compressed air. This process is supported by a refrigeration circuit, similar to that in air conditioning systems, which provides continuous and efficient cooling. The dryers are available in both air-cooled and water-cooled models to suit different environmental and operational conditions.
These dryers are widely used because of their reliability, low initial investment, and minimal maintenance requirements. They can effectively remove up to 75% of the moisture from compressed air, achieving dew points around +3°C to -20°C depending on configuration.
For general manufacturing, automotive, and packaging applications, refrigeration dryers provide a cost-effective and efficient solution to meet moderate dryness requirements.
However, they are less suitable for industries requiring ultra-dry air since they cannot achieve extremely low dew points. By combining simplicity, efficiency, and affordability, refrigerated air dryers remain the most common choice for standard industrial compressed air systems.
Why is the dryer used in a compressor?
Integrating an air dryer into a compressor system ensures reliable and efficient operation of downstream equipment. Without proper drying, compressed air carries high levels of water vapor that condense in pipelines and tools, causing corrosion, scaling, freezing, and bacterial contamination. Such conditions lead to frequent breakdowns, reduced efficiency, and product quality issues. In industries like food processing, pharmaceuticals, and electronics, uncontrolled moisture can contaminate products, creating costly recalls and safety hazards.
An air compressor dryer eliminates these risks by ensuring a stable supply of clean, dry air. This not only extends the lifespan of the compressor itself but also protects filters, valves, actuators, and other system components. Moreover, dry air improves energy efficiency, as corrosion-free pipelines reduce pressure drops and leakage risks. For companies, investing in a compressed air dryer reduces unplanned downtime, lowers maintenance costs, and helps maintain consistent production standards. Whether it is a refrigerated unit for general applications or a desiccant dryer for critical processes, the dryer is a vital part of every compressor system.
How to Select a Compressed Air Dryer
Choosing a suitable compressed air dryer requires careful assessment of application needs, system specifications, and operational costs. The first factor is the required dew point: industries like electronics or pharmaceuticals may require ultra-dry air at -40°C to -70°C, achievable only with desiccant dryers, while general manufacturing often requires a dew point of +3°C to -20°C, easily met with refrigerated dryers. Defining the target dew point ensures proper equipment selection.
Operating conditions such as ambient temperature, inlet air temperature, pressure, and flow rate must also be considered. For example, high-temperature compressed air may require specialized high-inlet-temperature refrigeration dryers or combination systems. Maintenance costs and long-term energy consumption are equally important; while desiccant dryers deliver superior performance, they generally involve higher operating expenses compared to refrigeration units. Evaluating the total cost of ownership helps balance performance with budget constraints. Finally, considering after-sales support, spare parts availability, and system integration ensures long-term reliability. With over two decades of expertise, Hangzhou Boda Purity Equipment Co., Ltd. provides tailored solutions across industries, offering a full range of compressed air dryers from refrigerated models to desiccant systems, helping customers achieve optimal air quality and operational efficiency.
Contact us online today to learn more about our compressed air dryer systems and discover how BODA GAS TECH can deliver the right solution for your application.
