Vapor-Lock Traits of Cars and Their Limitations on Gasoline Volatility 350101

THIS paper defines vapor lock as any interruption to the normal metering characteristics of a carburetor, due to vaporization of the fuel before passing through the carburetor jet.
Vapor lock may take the form of an excessively lean mixture supplied to the engine, if the gasoline boils in the carburetor jet; or it may take the form of an excessively rich mixture, if gasoline vapors in the float chamber build up sufficient pressure to drive fuel through the jet, a characteristic frequently described as “percolation.”
The two important classes of car operation which may produce vapor lock, that is, “running vapor lock” and “idling vapor lock,” are discussed, an analysis of vapor lock in fuel systems is made, and gasoline vapor-locking characteristics are treated.
Fuel-system temperature-tests are described and data thereon presented. Other features are the measurement of the vapor-handling capacity of fuel systems and fuel-system-loss measurements.
A detailed summary of the paper is made, and conclusions are drawn. Appendix 1 treats the subject of the apparatus for temperature measurements; Appendix 2, the water-displacement system used to protect the special test fuels from “weathering.”


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