Only the hoses specifically designed for air brake systems are legally allowed to be used on your air brake system if you plan to operate your vehicle on public roads. To gain D.O.T. approval, the hoses have to pass a series of tests prescribed by NHTSA. You can learn more about how the hoses get tested in order to comply at D.O.T.
So how do you know that a hose is legal (and safe) to use as an air brake hose? The only hose assemblies that you can legally use for air brakes are those clearly marked "DOT" on the hose layline as well as on both fittings. Anything else is not approved.
So why should you care? You should care because the air brake hoses are tested to perform in many different conditions which occur on and around your vehicle's air brake systems - not just pressure. Below is the list of the 14 different test areas that D.O.T. air brake hoses must pass in order to gain D.O.T. approval:
Construction
High temperature resistance
Low temperature resistance
Oil resistance
Ozone resistance
Length change
Adhesion
Internal clearance
Flex strength and pressure cycling
Corrosion resistance and burst strength
Tensile strength
Water absorption and tensile strength
Zinc chloride resistance
End fitting corrosion resistance
It takes a lot of engineering and testing to build an air brake assembly that is D.O.T. compliant, but for you it is easy to tell if you use any particular assembly - look for the D.O.T. designation on both the hose and the fittings.
