The explosion efficiency is one of the major problems in the equivalency method. The explosion
efficiency is used to adjust the estimate for a number of factors, including incomplete
mixing with air of the combustible material and incomplete conversion of the thermal energy
to mechanical energy. The explosion efficiency is empirical, with most flammable cloud estimates
varying between 1 % and lo%, as reported by a number of sources. Others have reported
5%, lo%, and 15% for flammable clouds of propane, diethyl ether, and acetylene, respectively.
Explosion efficiencies can also be defined for solid materials, such as ammonium nitrate