The Vapor-Locking Tendency of Aviation Gasolines ¹

PREVIOUS reports on the investigation of vapor lock in airplane fuel-systems have indicated that the tendency of aviation gasolines to cause trouble from vapor lock could be predicted from the standard A.S.T.M. distillation-data on the gasolines. The present paper deals with experiments made for the purpose of comparing the predicted conditions for vapor lock with those actually found in typical fuel-feed systems to cause trouble from this source. In gravity-feed systems, the predicted and experimentally observed conditions for vapor lock are in good agreement. On the suction side of a fuel pump, vapor lock occurs in a number of cases at lower temperatures than those predicted, particularly under conditions representing high-altitude flying in a system employing a long suction-lift.