SAE J844 Type A / Type B and DOT FMVSS 106 | Air Brake Tubing Specifications and Markings
Both SAE J844 and DOT FMVSS No. 106 are commonly referenced for air brake tubing used in North American commercial vehicles. Although both apply to air brake tubing, they address different requirements: SAE J844 defines technical requirements for nonmetallic air brake tubing, while FMVSS No. 106 sets U.S. federal requirements for brake tubing performance and marking.
When sourcing or verifying air brake tubing for North American applications, both SAE J844 and FMVSS No. 106 should be considered when interpreting product specifications and tubing markings.
What Are SAE J844 and FMVSS No. 106?
SAE J844: Technical Standard for Air Brake Tubing
SAE J844 is a technical standard for nonmetallic tubing used in vehicle air brake systems. It covers tubing construction, dimensions, and related performance requirements.
SAE J844 tubing is classified as Type A or Type B based on its construction: Type A is non-reinforced, while Type B has a reinforced construction.
SHPI offers SAE J844 Type A and Type B air brake tubing for fixed routing within the vehicle chassis and body.
FMVSS No. 106: U.S. Federal Safety Standard for Air Brake Tubing
FMVSS No. 106 is part of the U.S. Federal Motor Vehicle Safety Standards and includes specific performance and marking requirements for air brake tubing.
Performance testing includes high- and low-temperature performance, burst strength, oil resistance, vibration resistance, and dimensional stability after high-temperature or boiling-water conditioning.
Under SAE J844, Type A and Type B are classifications based on tubing construction. FMVSS No. 106, by contrast, sets U.S. federal requirements for safety performance and marking.
What Is the Difference Between SAE J844 Type A and Type B?
The main difference between Type A and Type B is whether the tubing has a reinforced construction.
| Specification | SAE J844 Type A | SAE J844 Type B |
|---|---|---|
| Tubing Construction | No reinforcement layer | Fiber-reinforced construction |
| SHPI Sizes | 1/8", 5/32", 3/16", 1/4", 5/16" | 3/8", 1/2", 5/8", 3/4" |
How to Select SAE J844 Type A or Type B?
Type A or Type B should be selected based on the original vehicle specification and tubing size. When servicing or replacing an existing line, follow the vehicle's original Type A or Type B specification.
Type B uses a reinforced construction that helps control tubing deformation under pressure. Type A and Type B represent different construction specifications; they do not represent higher or lower grades.
Although air brake tubing is commonly made of nylon, general industrial nylon tubing and tubing specifically designed for air brake systems have different application and compliance requirements. They should not be considered interchangeable based only on material or matching outside diameter.
→ What Is the Difference Between Air Brake Tubing and Nylon Tubing?
Type A / Type B Classification Is Separate from Tubing Configuration
Under SAE J844, Type A and Type B are construction classifications based on whether the tubing is reinforced. Fixed routing versus dynamic connection, however, depends on the installation location and whether the line must extend or move during operation.
Straight air brake tubing is typically used for fixed lines within the vehicle chassis and body. For connections between the tractor and trailer, where turning and changes in distance between the vehicles require the line to extend and retract, a coiled air brake hose is typically used.
→ Air Brake System Tubing Configuration
How to Read FMVSS No. 106 Markings on Air Brake Tubing
FMVSS No. 106 specifies required markings for air brake tubing, including the DOT symbol, manufacturer identification, date of manufacture, nominal outside diameter, and the letter A. The arrangement of the printed information and any additional markings may vary by manufacturer.
When reading tubing markings, it is important to distinguish the SAE J844 Type A / Type B classification from the letter A required by FMVSS No. 106.
Does the “A” Marking Mean SAE J844 Type A?
No.
Under FMVSS No. 106, the letter A indicates tubing for use in air brake systems. SAE J844 Type A, on the other hand, is a tubing construction classification.
As a result, SAE J844 Type B air brake tubing may display both “A” and “TYPE B.” The two markings have different meanings.
How to Select DOT Fittings for Air Brake Tubing
SAE J844 air brake tubing can be used with DOT fittings to connect system components such as brake valves, air reservoirs, and brake chambers. When selecting a fitting, first confirm the tubing outside diameter. If the fitting has a threaded end, the thread specification must also match the system port.