Difference Between Refrigerant Tubing & Utility Tubing

ACR Tubing

• Refrigerant tubing is known as air conditioning and refrigeration tubing. During manufacturing, moisture is removed from the inside of this tubing and the tube is filled with nitrogen gas and sealed. This process prevents oxidation from occurring inside the tube, and keeps dirt and other contaminants out of the system.

Utility Tubing

• Utility tubing comes in three different types, known as M, L and K. All three types are used for general plumbing, but each one has a different thickness that determines where it’s used. Type M copper piping is the thinnest and is usually used above ground, while Type K is used underground because it has the thickest walls. Type L, which is the most common tubing, is somewhere in between.

  L and K tubes are also used for heating systems, while Type K is used for gas lines. Most ACR tubing has an L thickness. Although utility tubing doesn’t cost as much as ACR tubing, you should never use Type L utility tubing in refrigeration systems because it’s not protected from contamination. Utility tubing also differs from ACR tubing in size.

Size

• Types M, L and K copper tubing are measured by their inside diameter, while refrigerant tubing is measured by its outside diameter. This is important to remember because the actual outside diameter of Types K, L and M tubes will always be 1/8 inch larger than their designated standard size, and the inside diameter will depend on how thick their walls are.

Identification

• Types K, L and M utility copper tubing must be marked to show tube type, manufacturer and the country of origin. This information must be incised into the tube and hard tubes must also print the information on the tube in a color that distinguishes it from the other tube types. Type K markings are green, Type L are blue and Type M are red. Soft coils or lengths don’t have to be marked with a color. Hard ACR tubes bear a blue color marking because they usually have a Type L thickness. Soft ACR tubes may not have any markings or incisions.