Onboard refueling vapor recovery

An Onboard refueling vapor recovery system (ORVR) is a vehicle fuel vapor emission control system that captures volatile organic compounds (VOC, potentially harmful vapors) during refueling. There are two types of vehicle emission control systems: the ORVR, and the Stage II vapor recovery system. Without either of these two systems, fuel vapors trapped inside gas tanks would be released into the atmosphere, each time refueling of the vehicle occurred. However, an ORVR system is able to retain those emissions, delivering them to the vehicle's carbon-filled canister and then to dispose of those vapors by adding them to the engine intake manifold and the stream of fuel supplying the engine, during normal operation. The goal behind implementing the ORVR system throughout the U.S. is to eventually make the Stage II systems obsolete.