Structure

Stage II Vapor Recovery Stage II Vapor Recovery is the capture and control of gasoline vapors that would normally be released into the atmosphere during the refueling of motor vehicles at a GDF. The image to the right represents a typical refueling utilizing Stage II Vapor Recovery. The black arrows represent the gasoline being pumped from the storage tank to the automobile. The red arrows show the flow of the vapors from the automobile tank back into the storage tank. These vapors are held in the storage tank until the next gasoline delivery when they are returned to the truck.Stage II Vapor Recovery is generally categorized by the “boot” on the nozzle that allows it to capture vapors during refueling. The hose used is a coaxial hose specially designed to allow gasoline to flow through an inner hose surrounded by larger hose that allows the vapors to be pushed back down to the storage tank.

The movement of the vapors from the automobile to the storage tank is done without the use of a pump. The vapors are pushed out of the tank by the incoming gasoline filling the tank. This is called a “balance system.” In some states, Vapor-Assist systems are used which actively pull vapors from the automobile into the storage tank when refueling. Missouri has approved only balance systems.