The ash analysis determines the amount of non-combustible material in the TBF. The ash may be composed of salts, minerals or other debris that does not burn at very high temperatures. The compounds that are present in the ash determination may contribute to wear of pumps and valves and may contain elements that will corrode or cause deposits on burner components. If high concentrations of non-combustibles are present, excessive ash in stack emissions may also occur resulting in violations of Clean Air Act regulations. The specification limit for ash in all grades of TBF is a maximum of 0.15% mass.