PEX has become popular for use in plumbing systems due to its durability and flexibility. For water lines, PEX pipes can withstand temperatures of up to 200℉. So, many people might be tempted to use PEX pipes for compressed air systems.
But can you use PEX for air lines? The answer is a bit mixed-up. PEX pipes aren’t rated for compressed air systems. But still, you can use specific types of PEX pipes for air lines.
Learn about various types of PEX pipes and their specifications to know which pipe you can use for air lines. Let’s get started.
What Are PEX Pipes? Can You Use PEX for Air Lines?
PEX stands for Cross-linked Polyethylene. It is made from polyethylene, where the molecular structure of the material is changed through physical or chemical processes. As a result, the polymer chains of polyethylene get crosslinked. The X in the name stands for cross-linking.
Due to the cross-linking, the temperature and pressure resistance of the material increases a lot. According to ASTM F877-23 standard, PEX pipes must have a pressure rating of 100 psi at 180℉. It also allows the pipe to be bent without cracking or bursting.
In simple words, PEX is a flexible plastic pipe that can withstand high temperatures, corrosion, thawing, and mineral buildup.
Sticking to the main question, can you use this pipe for air lines? Ideally, PEX isn’t designed for compressed air lines. But the pipe has some variations that can be used for air lines. PEX-AL-PEX is suitable for pressure systems, so you can use this pipe for compressed air lines.
PEX Tubing Types
Depending on how the PEX pipe is built, they are divided into different categories. Check out the main categories below to understand why any PEX isn’t the best pipe for air compressor lines.
PEX A
This is the earliest type of PEX where peroxides were used to form the material. Reactive free radicals from the heated peroxides caused cross-linking during extrusion. This type of pipe is known as PEX A.
The most prominent properties of these pipes are durability and flexibility. You can easily bend these pipes without cracking, so they are more suitable for tight areas. And as you can bend PEX A better, you will need fewer couplings in the system.
PEX B
Reactive silane molecules are grafted to polyethylene for making PEX B. Due to the heat treatment at the end, this pipe is a bit more rigid than the PEX A. So, you might not be able to bend it as much as a PEX pipe.
But PEX B is a bit stronger than PEX A. So, it will hold pressure better than the previous type.
PEX C
An electron beam method is used for crosslinking polyethylene and the result is the PEX C. Due to the cleaner process, PEX C is a bit more flexible than PEX B. But it might not be able to withstand pressures or temperatures as much as the PEX B.
PEX-AL-PEX
These pipes are also known as PAP pipes. Two PEX layers sandwich an aluminum layer, which makes the pipe extremely durable and flexible at the same time.
With almost zero vapor permeability, this pipe is rust and corrosion-resistant. And it is the best pipe for air compressor lines for its added strength.
Pros and Cons of PEX-AL-PEX for Air Lines
Before you use this pipe in air lines, know some crucial advantages and disadvantages of the pipe.
Pros
- PAP pipes are highly affordable, so you can use them in large systems
- It is flexible enough to bend where necessary
- No soldering is required for installation
- It has high resistance to corrosion and thawing
- You can connect PAP pipes with metal pipes
Cons
- PEX isn’t UV-resistant, so you can’t use it outdoors
- Making PEX connections require special tools and knowledge
- Not suitable outdoors
- Can’t be recycled
What Size PEX for Air Lines?
Understanding the SDR9 standard for PEX pipe sizes is crucial so that you can use the right PEX pipe for airlines. When choosing PEX pipes, you should check the inner diameter first. It can sometimes be denoted as Nominal Inner Diameter or Nominal ID.
The outer diameter, wall thickness, and bend radius of the PEX pipe will vary depending on the inner diameter. Here is a quick size chart for you.
| Nominal ID | OD | Wall Thickness | Bend Radius |
| 3/8 inches | 0.500 inches | 0.070 inches | 4 inches |
| 1/2 inches | 0.625 inches | 0.070 inches | 5 inches |
| 5/8 inches | 0.750 inches | 0.088 inches | 6 inches |
| 3/4 inches | 0.875 inches | 0.097 inches | 7 inches |
| 1 inch | 1.125 inches | 0.125 inches | 9 inches |
According to the Plastic Pipe Institute, water service lines use PEX pipes with inner diameters from 1/2 inches to 3 inches. But if you use them for compressed air, a 3/4 PEX air line is more suitable.
Remember, you need to select the PEX air line fittings carefully depending on the size of the PEX tubes.
FAQs
Check answers to some frequently asked questions about what pipe you can use for air lines.
Q: Can I use PVC for air compressor lines?
No. PVC isn’t suitable for compressed air lines. At high pressure, PVC pipes will rupture easily and can have an explosive effect to hurt the surroundings.
Q: How can I connect PEX pipes for air lines?
PEX pipes can be connected through compression fittings, copper crimps, or stainless steel cramps. Remember, you need special tools for connecting PEX pipes.
Q: What pressure can PEX pipes withstand?
Depending on the type, PEX pipes can withstand up to 800 psi of pressure. Watch this PEX pressure test to learn more.
Conclusion
PEX is a very durable and affordable material compared to traditional copper pipes. But when it comes to compressed air lines, you need to pause for a bit and think, ‘Can you use PEX for air lines?’
Fortunately, you can use PEX for air lines but that should be PEX-AL-PEX. Only this type of PEX pipe has the ability to work properly in air lines. So, choose the right PEX for your air lines and stay safe.