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Onboard refueling vapor recovery
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<p>An onboard refueling vapor recovery system (ORVR) is a vehicle fuel-vapor emission control system. It captures potentially harmful <a href="/facts/Volatile_organic_compound/BFMlKwgt">volatile organic compounds</a> (VOCs) during refueling. Without such a system, fuel vapors trapped inside gas tanks would be released into the atmosphere, each time the vehicle was refueled. </p><p>There are two types of vehicle fuel vapor emission control systems: the ORVR, and the older, less efficient "Stage II" <a href="/facts/Vapor_recovery/cbdvnama">vapor recovery</a> system. An ORVR system has the added benefit of being able to retain those emissions, by delivering them to the vehicle's <a href="/facts/Activated_carbon/YAbaXCcb">activated carbon</a>-filled canister. It later then disposes of the vapors by adding them to the engine's <a href="/facts/Inlet_manifold/VDPnE747">inlet manifold</a> during normal operation—and thus to the fuel/air mixture supplying the engine. </p><p>The goal behind implementing the ORVR system throughout the U.S. and other territories is to eventually make the Stage II systems obsolete. </p>