Editor's note: This post has been updated in November 2025 for comprehensiveness.
Struggling with moisture in your compressed air system?
Excess water isn’t just inconvenient; it can cause equipment corrosion, reduce performance, and lead to costly downtime.
In this guide, we’ll show you the most effective ways to remove moisture using air dryers, water separators, and filters. Follow these proven techniques to protect your equipment, boost efficiency, and keep your operations running smoothly, without the setbacks of water contamination.
Table of Contents (Jump to a Section):
- What Causes Moisture in Compressed Air?
- Why Moisture Removal is Critical for Your System
- 5 Best Practices to Prevent Moisture Buildup
- The Best, Cost-Effective Products to Remove Moisture from Air Lines
- Frequently Asked Questions About Water in Compressed Air Lines
STOP WATER DAMAGE: Achieve Clean, Dry Air.
Explore moisture-removal products at airlinehyd.com
Key Takeaways for Air Line Moisture Removal
Source of Moisture: Water in compressed air systems originates from various sources, including the ambient air and the compression process itself. Preventative Solutions: Effective measures include utilizing water separators, refrigerated air dryers, and desiccant air dryers to reduce or eliminate moisture. System Reliability: Ensuring your compressed air system undergoes routine maintenance and is regularly monitored helps prevent moisture buildup and detects problems before they escalate. |
What Causes Moisture in Compressed Air?
Increase in Temperature
One of the most prominent triggers for excess water in pneumatic air lines is atmospheric air temperature increases. As temperatures rise, water evaporates and humidifies the air that your pneumatics rely on. People often say that the problem isn't the heat but the humidity, and that's as true for compressed air as it is for us.
Remember, air humidity is compounded when it is compressed.
Did you know that a 25-horsepower compressor can release more than 18 gallons of water in one day during the summer? That's potentially a lot of moisture in your system!
Ambient Humidity
Apart from rising temperatures, high levels of ambient humidity can also contribute to the amount of water in your compressed air system. This is especially true for facilities located near bodies of water or areas with high rainfall. The moisture in the air surrounding your compressor will enter your system through the intake and cause issues if not properly managed.
Rapid Temperature Changes
Another trigger is when the air temperature changes quickly. This can include fluctuations in the ambient air of your operations or changes within the system itself.
For example, people often place air compressors outside or in a different (non-temperature-controlled) room away from the rest of the system. During the warmer months, that compressor could deliver hot compressed air into cold, air-conditioned indoor areas. That is a recipe for condensation as the warm, humidified air runs through cool, refrigerated pipes.
Why Moisture Removal is Critical for Your System
It's natural for water to be present in the air and fluctuate between its gas and liquid states. So why is even a tiny amount of water in your air line so harmful? Simply put, it can significantly dent your wallet and bottom line. Here are a few of the most common issues that occur when excess moisture goes unchecked.
Loss of Lubrication ➜ Component Failure
Pneumatic components are pre-lubricated at the factory, protecting them from premature wear and allowing them to function properly. Unfortunately, it does not take much water to compromise this lubrication or even wash it away entirely. When subjected to moisture from compressed air, the rubber seals within these components are also prone to swelling, stiffening, and deterioration. All of this leads to premature wear and the eventual failure of the components.
Corrosion
Water also introduces the risk of corrosion within your compressed air system. Any metal components exposed to moisture are at risk of rust and degradation, which can lead to a significant decrease in equipment lifespan and efficiency.
Pipe Scale and Rust
Moisture also causes pipe scale and rust to form. As rust builds in the system, it decreases the pipe's interior surface area, allowing less air to pass through and reducing the system's performance.
Over time, the pipe scale and rust will detach from the piping and cause even more problems as they travel through the pneumatic system. The components within a pneumatic system are precise and intricate. When chunks of debris encounter the tiny inner workings and passageways, they become clogged rather quickly, resulting in poor performance and, ultimately, system failure.
Increased Costs
Water in your compressed air lines can lead to unplanned work stoppages, possibly creating long downtimes to source, purchase, and replace the damaged components. At worst, portions of the final product will come into contact with the moisture and debris from the compressed air, causing latent damage and quality issues along with eventual system failure. All of these scenarios, unfortunately, lead to reduced profits.
Poor Air Quality for Important Processes
If compressed air is used directly in your product or processes, it's even more critical to remove moisture, and the byproducts moisture produces (bacteria, rust, and debris).
Think about a paint booth or food processing plant, both of which relies heavily on compressed air tools. The rust and bacteria that make their way through the air lines will greatly decrease the paint's finishing qualities and cause health concerns for the food processing plant. Even places that use small blasts of air from blowguns to clean parts and products will not want to subject them to moist air carrying mold and rust.
Bacterial Growth
There is one thing that all bacteria and microorganisms need to thrive... moisture.
When this is introduced, your pneumatic lines become breeding grounds for mold and bacteria. This accumulation will ultimately gunk up your system to reduce your airflow, as well as become a potential health and safety concern for those in contact with the system or end product!
But there is good news! These issues are preventable, and we will discuss the best practices to keep your compressed air system free from water.
5 Best Practices to Prevent Moisture Buildup
As we've learned, moisture in your compressed air lines can be a huge problem. So here are some of the best ways you can prevent moisture build-up in the first place.
1. Drain the Air Compressor
Air compressor tanks often contain a drain at the bottom to release collected water. Make sure you drain your air compressor regularly, especially during the warm months when it will accumulate faster. Remember, more demand will require more frequent draining.
2. Create Consistent Ambient Air Temperatures
Pay attention to differences in temperatures within your system. Remember that water vapors turn into liquid when passing from a warmer to a colder area, so design your pneumatic system to avoid such rapid temperature changes.
3. Choose Proper System Materials
Some metals, like steel, are prone to rust and pipe scale. Other materials, such as marine-grade aluminum pipes, are more rust-resistant and help prevent oxidation-based contamination.
Implementing a piping system with cleaner interior surfaces decreases issues related to moisture build-up and increases your system's airflow and integrity, so make sure to choose the best material to suit your needs.
4. Adjust Pipe Direction
Water vapor typically collects and pools at the bottom of the pipe as it condenses. One way to prevent this water from entering the rest of your system is to adjust where the other pipes connect to the mainline. By connecting these pipes at the top of the air line (instead of at the bottom where the water collects), you are more likely to provide dryer air into the rest of the system. This method will not eliminate water, but it will help minimize damages that could occur further down the line.
5. The Best, Cost-Effective Products to Remove Moisture from Air Lines
While the above practices to prevent moisture should be applied when possible, they may not be enough or cannot be applied to your system. In this case, there are numerous great products to help remove the excess water from your system.
All of these products are available on our website, airlinehyd.com.
Filter and Regulators
Air Filter/regulators are essential components of pneumatic air lines that provide two critical functions:
1. Filtration: They filter the compressed air, removing dirt, dust, and moisture from the air to ensure that the air entering the system is clean and dry. This helps prevent damage to the pneumatic equipment, ensures reliable operation, and improves the system's lifespan.
2. Regulation: They regulate the pressure of the compressed air, maintaining a constant and consistent pressure level throughout the system. This helps prevent damage to the pneumatic equipment and ensures that the system operates efficiently and safely.
A great air filter/regulator that reduces moisture and debris is the AW30 by SMC. This product works especially well if your system has high airflow, as the AW30 uses a cyclone effect to spin the air at high speeds. The cyclone effectively forces water and debris to the sides of the unit, where it becomes separated and drains out the bottom. This component requires a hefty amount of air pressure to function, so if that is lacking in your system, you may want to consider a different solution.
Water Separators and Filters
Water separators, also called main-line filters, come in various sizes to remove water and other contaminants from the compressed air before it enters the main air line. They are typically installed at the beginning of the main air line, just after the compressor and before the regulator, to ensure that the air going into the system is clean, dry, and free of contaminants that could damage the equipment.
Water separators use a variety of filtration methods to remove moisture and contaminants from the compressed air, such as centrifugal force, coalescing filters, and adsorption filters. Some water separators also have automatic drain valves that periodically release the accumulated water and contaminants from the system.
A great example is SMC's AMG water separator, which effectively removes 99% of the water from pneumatic lines.
To truly understand the problem and see the solution in action, watch the video below. It clearly demonstrates not only why water is so destructive (loss of lubrication, corrosion), but also how the SMC AMG unit instantaneously stops the water from reaching your downstream equipment.
Video not loading? Watch on YouTube
Air Dryers for Compressed Air
Air dryers are another option for keeping water out of your pipes. Imagine you have a larger facility and are experiencing water throughout all of your air lines. This is where an air dryer would help, as they're designed for large water removal issues.
Air dryers are typically installed in larger pneumatic systems that require high-quality, clean, and dry compressed air. They help prevent damage to pneumatic equipment, ensure reliable operation, and improve the system's lifespan.
There are several types of air dryers, including the refrigerated air dryer, desiccant air dryer, and membrane air dryer.
Refrigerated Air Dryers
The refrigerated air dryer can be thought of almost like a dehumidifier. As wet air comes into contact with the dryer, it is significantly cooled down, which turns the water vapor into actual liquid water. That water goes into a water trap. The cold air then goes through a process to heat back up to room temperature, resulting in dryer air. An excellent refrigerated air dryer to consider is SMC's IDFB refrigerated air dryer (pictured). These durable units have simple control systems and are easily serviced.
Membrane Air Dryers
The membrane air dryer is designed for convenient point-of-use drying without the need for electrical power. It utilizes hollow fiber membranes to remove water vapor from compressed air. The drying power of the membrane is controlled by varying the compressed air flow rate and pressure. SMC offers the IDG, Membrane Air Dryer Series (pictured), which can combine a mist separator and micro mist separator with a single unit.
Desiccant Air Dryers
The desiccant air dryer uses an absorption material, such as silica gel, to absorb the water vapor within the lines. The vapor then turns to liquid and sticks to the contents until they are cleaned out. SMC's regenerative desiccant drying systems, the ID and IDW series (pictured), provide the greatest level of drying capability among widely available drying technologies.
With any air dryer, it's important to make sure the air pressure and capacity fit the compressor. Prices range from a few hundred dollars to several thousand, so make sure you do your homework or contact a professional before making a purchase.
Other Temperature Control Products
The above-mentioned products are just a few examples of moisture and temperature control products. Airline offers a wide array of options you can shop online here. If you need additional help with your selection, contact our customer support, and our specialists will be happy to offer technical support.
Moisture in air lines causes major issues, ranging from component failure to unplanned downtime from system failure. By implementing these practices and cost-effective products, you can achieve clean and dry air during every season (even the hot and humid summer months). If you need help determining the most useful solution for your application, talk to an Airline expert. We can help you determine the best solution for your business's needs.
Frequently Asked Questions About Water in Compressed Air LinesHow often should I drain my air compressor tank?
Can moisture in compressed air lines cause health issues?
How can I determine if my compressed air system needs a water separator?
For more information about checking your system for water, read our troubleshooting guide. Are there any signs of excessive moisture in compressed air lines I should watch out for?
What are the best practices for installing a water separator in my compressed air system?
How often should filters and water separators be replaced or maintained?
Can using an air dryer replace the need for a water separator?
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Additional Resources
- Water in Compressed Air Lines: Complete Troubleshooting Guide
- Learn About SMC
- SMC Product Configurator
- Shop Pneumatic Components
- More Pneumatic Blog Posts
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