IT is the purpose of this paper to present a chart by means of which the vapor-locking characteristics of a gasoline (represented by a curve showing the quantity of vapor formed as a function of the temperature) can be estimated with moderate accuracy for gasolines in the current commercial distillation ranges from the conventional Reid vapor pressure and A.S.T.M. distillation tests on the gasoline.
Interpretation and consolidation of car data are facilitated by means of the chart and, in this respect, vapor-lock test data are given for eight 1934, eleven 1935, and several 1936 model cars.
The use of the chart and car data is illustrated by a group of sample problems which are specially designed to show the degree of assurance that may be placed on the use of either Reid vapor pressure or A.S.T.M. 10 per cent point alone as a criterion of vapor lock.
The problem of evaporation losses from the fuel system, which can be roughly treated by means of the chart, is also discussed briefly.
Finally, the application of the chart to the proposed test methods of the C.F.R. and A.P.I. Committees is indicated.