Measure evaporation residue in aviation fuels, motor gasolines, and other volatile distillates in accordance with ASTM D 381, ISO 6246, EN 5 and IP 131 test methods. The HGT 915 uses air evaporation, while the HGT 917 offers the versatility of either air or steam evaporation. Both models are capable of testing three 100 ml samples simultaneously. Results indicate the likelihood of induction system deposits and potential sticking of intake valves.