Vapor emission recovery and measuring method and vapor recovery collection boot

A testing method and apparatus for use at service stations to establish whether gasoline refueling systems meet government regulations for gasoline vapor emission. The apparatus includes a boot used to surround a gasoline dispensing nozzle while delivering gasoline to an automobile gas tank. The boot is of flexible material and has a hollow wall defining a vapor collection chamber, the inner part of the hollow wall having apertures distributed over its surface to allow gasoline vapor to be drawn into the chamber by suction. The outer part of the hollow wall has a stub connectable to a tube leading to vapor emission analyzing equipment. In the method, such a boot is used to recover the emitted vapors directly from the vehicle-nozzle interface region and the recovered vapors are drawn by a pump through a flow meter and delivered to an analyzer. The outputs of the flow meter and analyzer may be delivered to a computing device to determine the mass emission rate of hydrocarbons and the accumulated total hydrocarbon mass emitted.