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VAPOR RECOVERY SYSTEM
Petroleum tanks typically include a vapor recovery system to move vapor in and out of the tank in a closed system. This system allows for circulation of the vapors so they do not escape into the atmosphere. The vapors inside the tank are displaced as the tank is bottom loaded. The vapors are moved to the loading facility during this bottom loading process. The vapors inside the underground storage tank at the typical service station are displaced as the tanker drops fuel and those vapors are moved to the tanker as its payload is off-loaded. The vapor recovery system includes a vent on top of the tank, a vapor rail that runs the length of the tank, a vapor pipe between the vapor rail on top of the tank and the discharge area, and vapor recovery outlets at ground level. The vapor vents are inward opening, air operated valves located in the manholes on the top of the tank. These vents are open when the emergency valve(s) in the bottom of the tank are open for product loading or product discharge. There is a vent for every compartment and each is piped to the vapor rail with a hose. The vapor rail collects the vapors from each compartment and is connected to piping that runs from the top of the tank to the curb side bottom load area where the vapor recovery outlets are located. Vapor recovery tee piping can also be included to the street-side of the trailer. The piping from the vapor rail to the bottom load area may run through the tank or be an external pipe typically located at the rear of the tank. There can be several vapor recovery outlets depending on operational needs. Some or all of these outlets may have a brake interlock valve to set the brakes if a
UPPER VAPOR RECOVERY VENT
LOWER VAPOR RECOVERY OUTLET
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