For safety, use nitrogen or other inert gas for EVAP testing. This avoids the danger of adding oxygen into a vehicle’s fuel tank and creating a flammable fuel vapor mixture inside the fuel system. Again, beware: any company claiming anything else, is obviously not licensed to use our patented inert gas technology.
The basic laws of physics are clear, and SAE International has published several papers that agree: the proper use of an inert gas is the only way to eliminate the risk of fire or explosion when EVAP testing a fuel tank. Virtually all OEMs require nitrogen for safer testing and the EPA strongly recommends it. When testing vacuum, exhaust and other systems, shop air is fine. But when doing EVAP testing, why take chances?