Published: 29/08/2023
Everything You Need to Know About Compressed Air Dryers
Air dryers are designed to remove moisture from compressed air, resulting in a more efficient machine and a lower chance of breakdown.
Droplets of water are never a good sign when found in your compressor system. Moisture tends to indicate corrosion, which can result in damage over the long term.
Whether you’re already using a compressed air system or considering investing in a compressor for the first time, it’s essential to consider whether you’ll need a compressor air dryer.
In this blog, we’ll cover what compressed air dryers are, why they’re important, how they work, and the main types of dryers.
What is a compressed air dryer?
A compressed air dryer is a filtering system that removes moisture created during the compression process of your compressed air. Air compressor dryers are designed to ensure that your compressed air is free of moisture that can damage the machine over time or reduce its inefficiency.
Why are compressed air dryers important?
Many environments or applications where compressed air is used are sensitive to water and moisture. Water in the compressed air can contaminate the end products or damage tools and equipment. Lower-quality compressed air full of moisture can ultimately lead to a loss of money and time.
An air dryer can help increase your production machine’s lifespan and efficiency with the use of high-quality compressed air. This is especially important in the pharmaceutical and food industries, where clean and dry air is essential.
How do compressed air dryers work?
The exact technique used to achieve clean, dry air will depend on the level of dryness required. Each type works differently, but they all work by suppressing the dew point of the air by removing any water particles.
There are four main types of air dryers for compressors, which operate using different mechanisms to remove moisture from compressed air. We’ll review how the four main types of air dryers work below.
Refrigerated air dryers
Refrigerating air dryers use low temperatures to remove moisture from the compressed air. The compressed air is cooled to approximately 3°C (known as the dew point) so the air’s moisture condenses and can then be drained. The air is then reheated back to room temperature before being used.
This is the most common type of air, and it works well for various applications. However, because they don’t remove all the moisture from the air, they’re not suitable for applications requiring completely moisture-free air.
There are two subcategories of refrigerant dryers:
- Cycling dryers turn off and on as needed to dry the compressed air effectively. They are the more energy-efficient and environmentally friendly option. However, they require more maintenance due to their extra parts.
- Non-cycling dryers run continuously to maintain a constant dew point. They are reliable and simple to maintain. However, the downside is that you can’t turn them off, meaning they’ll stay running even when the compressor is not being used.
Adsorption air dryers
An adsorption or desiccant air dryer is usually used as a second-stage dryer (for example, after a refrigerating dryer). This dryer uses a porous hygroscopic medium, like activated alumina or silica gel, to dry compressed air. This results in a significantly lower dew point (around -40°C.) and much drier air.
There are two main types of adsorption air dryers: single-canister and twin-tower desiccant dryers. Single-tower dryers are often used for point-of-use applications because they are efficient and easy to use. They use a granular hygroscopic medium to dry and filter the air of moisture.
Twin-tower dryers (also known as regenerative dryers) contain 2 canisters. The air passes through the hygroscopic medium in the first canister and then flows through the medium in the second tower once the medium is saturated, to dry and regenerate the tower.
Learn more about Adsorption Dryers in our blog: Adsorption Air Dryer Working Principle: Everything you need to know
Deliquescent air dryers
Deliquescent dryers work similarly to desiccant dryers. Compressed air passes through a hygroscopic medium to remove moisture. However, unlike desiccant dryers, deliquescent dryers use soluble salt tablets, which must be drained and replaced regularly.
Additionally, the dew point (the temperature of the dried air) will change depending on the temperature of the compressed air that enters the dryer.
They are commonly used in remote environments as no electricity is required to operate them. They’re ideal for applications involving contaminated air or natural and waste gases.
Membrane air dryers
A membrane air dryer dries incoming air over a hygroscopic membrane. The air pressure builds up on one side of the membrane before being carried through to the other, which is a lower pressure. The moisture is then carried away when a dry gas is run through it.
Like deliquescent air dryers, the dew point depends on the temperature of the incoming air, and they’re often used as second or third-stage air dryers. They’re commonly used in medical or dental industries because they result in high-quality, dry air.
How Air Supply can help
At Air Supply, we have decades of experience selling, servicing, and repairing a huge range of air compressors and compressed air equipment. We stock a variety of high-quality air dryers, including adsorption air dryers and refrigerant air dryers, to ensure your compressed air is dry and moisture-free.
We offer one of the largest stocks of used air equipment and compressed air dryers in the UK, which is a great option if you’re on a limited budget or wish to try a dryer for your business for the first time.
If you’re still unsure if your business would benefit from a compressor air dryer, our friendly team will be happy to advise you. Get in touch with us today to find out more about our products and services and the best solution for your compressed air needs.