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Air Compressor Aftercooler – All Things You Must Know

air compressor aftercooler

Did you know that the regular air we breathe has some degree of water within its molecules? This can be high or low, depending on your geographic zone. Therefore, an essential step to make compressed air is to remove all that water and moisture from the ambient air. We do this by using an aftercooler. This is a fantastic instrument that’s in all your air compressors, but not many people know how it works.

If you want to know more about aftercoolers, keep reading this guide that’s going to walk you through everything we know about them.

What Is an Air Compressor Aftercooler?

Aftercoolers are mechanical devices that work as heat exchangers to purify and remove all moisture from the air we breathe to create compressed air. This allows the air to be as dry as needed to properly work in the air compressors. Moreover, it has three primary functions.

  • Make the air colder.

  • Eliminate the moisture.

  • Prevent other devices from getting damaged due to excessive heat.

How Do Air Compressor Aftercoolers Work?

Most aftercoolers are made of a tube with either water or air through which the compressed air passes. This is meant to remove all the water and heat until it reaches the desired level. Air-coolers usually combine ambient air with compressed air to exchange heat, while water-coolers make the air colder by running through the tubes alongside the air.

Why Are Aftercoolers Required?

Air compressors use extremely hot air, but this air must be regulated to reach the desired temperature. This is done to avoid overly high temperatures that could damage your equipment and vapor that would create rust in the compressor. Water becomes more concentrated as it gets hotter, so it is essential to make the vapor cooler than the dew point temperature and condensate it into water.

Otherwise, you would end up with too many gallons of water being propelled into your devices in the steam, which could ultimately ruin them.

Why Do You Need to Dry Compressed Air?

If you live in tropical areas, or you’re simply going through a rough summer, the chances are that your compressed air is going to be filled with much more water vapor than usual, making it a lot more saturated. Using compressed air with such high water levels isn’t suitable for most industrial processes or other activities you’re going to be using it for, as it could damage your tools and mess up the final product. Moreover, it could even damage your air compressors by accumulating harmful water that ends up rusting its elements and creating blockages within its airlines.

When you dry compressed air, the aftercooler removes harmful water from it, and it prevents your power tools from getting damaged. However, you can always test your compressed air by holding it to international standards and ensuring everything is working the way it should.

Testing your air isn’t as easy as you may think, as it involves several studies that must be strictly done in a laboratory. Still, if you’re using compressed air for industrial means, investing in getting your air tested and standardized is worth the price.

How Do You Make a Compressed Air Cooler?

We’ve already settled why air coolers are so important, as these resemble what an air conditioner does to your house. It removes heat from the inside and replaces it with cool air. However, if you want to learn how to build one, you’re going to need to know more about the specifics of this device.

Most air coolers are made of a condenser, a compressor, and an evaporator. The condenser is placed outside the unit, the evaporator inside, and the compressor is the channel between them.

Moreover, the warm air should go through the evaporator where the cool air or water is meant to absorb the heat and release it through the vents. Then, the cool air is supposed to be pushed through the compressor. This process can be repeated as many times as you need to use your compressed air system.

However, keep in mind that building an air compressor is a rather tricky job, and it requires an expert’s mind and skills to do it properly. Nonetheless, you’re free to try it out by yourself, but be as cautious as possible, so you don’t get hurt.

Types of Aftercoolers

Most aftercoolers come in two varieties, air-cooled and water-cooled. However, each of them has differences that can help you decide which one is going to give you better results. Please keep reading to find out more about it.

  • Air-cooled aftercoolers rely on the ambient air to regulate the vapor in the compressor. This air enters the compressor through a spiral tube, and it’s cooled by the air in the motor-driven fan, which removes all the heat and brings it as close as possible to ambient air temperature. This process also eliminates up to 75% of the water vapor in the compressed air, which is then separated and drained using the compressor’s valve. Keep in mind that this valve must be emptied after you’re done using the tool.

  • Belt guard air-cooled aftercoolers also use ambient air. However, they use a v-belt guard to make the heat transfer much more efficient, and they also contribute to maintaining a regulated temperature for a more extensive time.

  • Water-cooled aftercoolers are exclusively used for stationary compressor installations. Still, they have some interesting perks that you should be aware of, such as the lack of temperature fluctuation in the water, the cost-effectiveness of the liquid method in large quantities, and its availability. Water also cools the air much faster and reaches lower temperatures than ambient air. Moreover, these compressors come in several styles, but the most common are made of a shell and a tube. In the shell and tube method, the water absorbs all the heat from the compressed air, as the tubes suck out all the excess moisture in it by using a moisture separator and a drain valve.

How to Measure an Aftercooler

If you want to find an adequate aftercooler for you, then you need to learn how to measure it. In order to do this, you’re going to need three key metrics, CFM, PSI, and overall temperature. However, finding the CFM and the PSI is going to be the easier thing to do, as it is most likely going to be within the compressor’s indications, but calculating the temperature is going to be a little bit trickier.

Overall, most compressed air systems use a cold temperature difference or CTD from around 10 to 20 degrees. This makes the compressed air be at a temperature equal to the average cooling temperature plus the CTD. However, suppose you want to create colder ambient air. In that case, you’re going to need a larger air-cooled aftercooler, but remember to check the maximum temperature that your device can tolerate before getting damaged, so you don’t make any mistakes later on.

Moreover, understanding the requirements of your air-cooled aftercooler can help you choose a better one that meets all your current needs and expectations. This may not be necessary if your air compressor includes one, but if it doesn’t, you’re going to need to buy one before being able to use the compressor.

Differences Between Aftercoolers VS. Intercoolers

It is also important to mention the difference between aftercoolers and intercoolers, which are sometimes interchangeable, but in reality, they are two completely different tools. An intercooler is similar to an aftercooler, as both are heat exchangers that make the compressed air colder until it reaches ambient air temperatures.

However, intercoolers are used strictly in turbocharged engines before the air enters the machinery, which allows the compressor to take in more air. This slight difference increases the air’s density and makes it much more efficient once you start using your tools.

Moreover, aftercoolers and intercoolers share many characteristics, but they differ in the way they’re used, and the one you choose is going to depend on your system’s necessities.

Benefits of Having an Aftercooler

If you made it this far, you probably know all the reasons why you should incorporate an air-cooled aftercooler into your air compressor. Still, there are several other benefits we haven’t discussed and that you should know before making your purchase.

  • Dry air is essential if you want to keep your work as professional as possible, as some materials can get damaged when in contact with water or moisture.

  • Aftercoolers also help your equipment last longer, as it protects it from getting excessive moisture into its system.

  • If you have an air-cooled aftercooler, you aren’t going to need a huge dryer, as the air is already treated before it even needs to be dried. Therefore, you can spare some money and buy a smaller dryer for your compressor.

  • It helps you stay safe, as it reduces the risk of explosions or combustion due to the high heat levels and pressure in the compressor’s copper pipe. If you want to know more about air compressors and explosions, you can check out this article.

Moreover, an air-cooled aftercooler is a fantastic investment and necessary if you work with a compressed air system every day. Please don’t overlook the importance of having one, as integrating it into your compressor can make a whole world of difference.

Bottom Line

Air-cooled aftercoolers work fantastically with all types of compressors, and you can avoid hot compressed air by just installing one and letting it do its job. Moreover, don’t forget how vital it is to do proper maintenance on all your devices. If you want to know more about the world of air compressors, don’t hesitate to check out the rest of our page.


What is an air compressor aftercooler?

An air compressor aftercooler is a mechanical device that removes moisture from the air to create compressed air. It works as a heat exchanger to cool down the air and prevent excessive heat that can damage equipment.

How do air compressor aftercoolers work?

Aftercoolers are made of a tube with either water or air through which the compressed air passes. The air is cooled down until it reaches the desired level, and the moisture is eliminated.

Why are aftercoolers required?

Aftercoolers are required to regulate the temperature of the air in the compressor, avoid rust in the compressor, and prevent damage to equipment due to excessive heat and moisture.

Why do you need to dry compressed air?

You need to dry compressed air to prevent damage to tools and equipment, avoid creating blockages within airlines, and ensure the final product is not ruined.

How do you make a compressed air cooler?

A compressed air cooler is made of a condenser, a compressor, and an evaporator. The warm air passes through the evaporator where the cool air or water absorbs the heat, and the cool air is then pushed through the compressor.

What are the types of aftercoolers?

The two types of aftercoolers are air-cooled and water-cooled.

How to measure an aftercooler?

To measure an aftercooler, you need to know the CFM, PSI, and overall temperature.

What are the differences between aftercoolers and intercoolers?

Aftercoolers and intercoolers are two different tools that are similar in some ways. Intercoolers are used in turbocharged engines before the air enters the machinery, while aftercoolers are used in air compressors to cool down the air and remove moisture.

What are the benefits of having an aftercooler?

The benefits of having an aftercooler include dry air for professional work, longer equipment life, cost-effectiveness, and improved safety by reducing the risk of explosions or combustion.

Are air-cooled aftercoolers necessary?

Yes, air-cooled aftercoolers are necessary if you work with a compressed air system every day. They can prevent damage to equipment and ensure the final product is not ruined.

Picture of Daniel Lewis

Daniel Lewis

Live in Chicago Illinois.
A contractor with10 years of experience.
Works with air compressors for various uses.

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