Vapor recovery is the process of recovering the vapor

Vapor

A vapor or vapour is a substance in the gas phase at a temperature lower than its critical point....

s of gasoline

Gasoline

Gasoline , or petrol , is a toxic, translucent, petroleum-derived liquid that is primarily used as a fuel in internal combustion engines. It consists mostly of organic compounds obtained by the fractional distillation of petroleum, enhanced with a variety of additives. Some gasolines also contain...

 or other fuel

Fuel

Fuel is any material that stores energy that can later be extracted to perform mechanical work in a controlled manner. Most fuels used by humans undergo combustion, a redox reaction in which a combustible substance releases energy after it ignites and reacts with the oxygen in the air...

s, so that they do not escape into the atmosphere

Atmosphere

An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...

. This is often done (or required by law

Law

Law is a system of rules and guidelines which are enforced through social institutions to govern behavior, wherever possible. It shapes politics, economics and society in numerous ways and serves as a social mediator of relations between people. Contract law regulates everything from buying a bus...

) at filling station

Filling station

A filling station, also known as a fueling station, garage, gasbar , gas station , petrol bunk , petrol pump , petrol garage, petrol kiosk , petrol station "'servo"' in Australia or service station, is a facility which sells fuel and lubricants...

s, in order to reduce noxious and potentially explosive fumes and pollution

Pollution

Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...

.

The negative pressure

Pressure

Pressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...

 created in the (underground) tank

Tank

A tank is a tracked, armoured fighting vehicle designed for front-line combat which combines operational mobility, tactical offensive, and defensive capabilities...

 by the withdrawal is usually used to pull in the vapors. They are drawn-in through holes in the side of the nozzle

Nozzle

A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....

 and travel through special hose

Hose (tubing)

A hose is a hollow tube designed to carry fluids from one location to another. Hoses are also sometimes called pipes , or more generally tubing...

s which have a return path.

Other industries

Vapor recovery is also used in the chemical process industry to remove and recover vapors from storage tanks. The vapors are usually either environmentally hazardous, or valuable to be recovered. The process consists of a closed venting system from the storage tank ullage space to a vapor recovery unit (VRU) which will recover the vapors for return to the process or destroy them, usually by oxidation.

Vapor recovery units are also becoming commonly used in the oil and gas industry as a means of recovering natural gas vapor and making it a usable and profitable product. Specifically a newer form of vapor recovery technology, Ejector Vapor Recovery Units create a closed loop system which not only recovers valuable vapor, but also reduces methane and VOC emissions.