How to Select the Right Tubing

In the world of maintenance, repair and operations, fluid flow can be among the most complex subjects.

Selecting the right tubing, fittings and other components is vital for safety and reliability. But how do you choose the right tubing for your application?

To start, pneumatic tubing can be broken down into two large groups: air brake tubing (also known as Department of Transportation/DOT-approved tubing or DOT tubing) and other tubing (non-DOT).

Air Brake (DOT) Tubing

The U.S. Department of Transportation (DOT) holds a high standard for over-the-road vehicles using air brake systems. Heavy-duty vehicles that travel on the road, such as semi tractors and trailers and buses, require DOT-approved air brake systems, and each component of an air brake system must comply with DOT standards. This ensures the tubing and fittings work together as a system to reduce failures and accidents. Other heavy-duty vehicles that use air brakes, like agricultural and off-road equipment, might not require DOT approval.

Money is not the only motivator when it comes to having DOT-compliant air brake systems. Safety also is pivotal and plays a huge role in the high standards that have been adopted. There are many styles and types of fittings, tubing and hose, but only those that meet the strictest requirements get the DOT stamp of approval.

How do you ensure your air brake system is DOT compliant?

First, make sure your system is using the proper fittings, because not all fittings are DOT approved. You are in the clear if your air brake system is using fittings that are properly marked DOT or Air Brake (A.B.), which includes both instant connecting and compression-style air brake fittings. Kimball Midwest carries several DOT lines, including Kimposite DOT, Brass DOT Push-In and Parker® DOT.

Air brake systems are typically plumbed with either synthetic tubing (that is clearly marked and identified as air brake tubing) or with copper tubing (although copper tubing on an air brake system is rare). Some of Kimball Midwest’s synthetic offerings are Kimposite Air Brake Tubing, Synflex® Eclipse™ and Nylon Air Brake Tubing.

If you’re unsure how to tell if your system is DOT compliant, simply look at the components it’s made of. DOT-approved fittings, tubing and hose will have the DOT identification right on the part.

Non-DOT Tubing

When looking at non-DOT tubing options, the environment in which the tubing will be used and the fluid being conveyed will be the major factors in selecting the correct style.

Most tubing is resistant to a variety of chemicals, but always be sure to confirm that the material the tubing is made of is compatible with the chemical that will flow through.

If your tubing needs to adhere to food grade (FDA) / NSF standards, you can use polyurethane or PT200 PVC tubing.

If your tubing needs to work in an environment with high or low temperatures, Nylon 11 tubing is a good choice because it’s rated for a range of -40°F to 200°F.

If your tubing needs to be extremely flexible for routing purposes, polyurethane tubing is ideal. It’s even resistant to kinks, making routing easy, even in tight spaces. Polyurethane tubing also has excellent abrasion resistance, reducing chances of failure in applications where some abrasion or rubbing is unavoidable.

Both polyurethane and Nylon 11 tubing are available in metric sizes to work with equipment using metric fittings.

No matter what tubing is selected, make sure the published working pressure of the tubing and fittings falls within the range of your application.

Finally, be sure to select the correct fittings for the tubing being used:

• For tubing used in applications regulated by the Food and Drug Administration or National Science Foundation, use the Super Speedfit®, NSF Kimposite or Legris Nickel-Plated
• For applications where light weight is beneficial and a wide range of sizes and styles are needed, select the Kimposite or Legris line of fittings.
• If you are not sure what style of threads you will encounter on the equipment you service, the Uni-Max lines of fittings have a special thread that will work with both Inch and British pipe threads.
• With applications requiring higher working pressures, the Prestolok® fittings are rated up to 300 P.S.I., depending on tube size.

No matter what tubing you're looking for, or even if you're not sure what the right choice is for your operation, your Kimball Midwest sales representative can help you make the right connections. If you don't have one, we'd love to help you .