Vapor recovery is the practice of capturing hydrocarbon vapors that would otherwise escape from storage tanks and other equipment, and routing them to sales, fuel, or control instead of venting or flaring them. It is a core method for cutting emissions and recovering saleable product on oil and gas sites.
Vapor Recovery in one line: Vapor recovery is the collection of hydrocarbon vapors that evaporate or flash out of tanks and vessels, keeping them out of the atmosphere. The vapors are captured under low pressure and compressed for sale or use as fuel, rather than being vented or flared. It reduces volatile organic compound and methane emissions while recovering a valuable gas stream.
Crude oil and condensate held in atmospheric storage tanks give off vapor for several reasons. Flashing occurs when liquid arriving from higher-pressure separation drops to tank pressure and releases dissolved light ends. Working losses come from filling and emptying, which pushes vapor out as liquid level rises. Standing or breathing losses come from day-night temperature and pressure swings. Together these produce a continuous stream of light hydrocarbons and volatile organic compounds.
Left uncontrolled, this vapor is either vented to the atmosphere or sent to a flare. Venting releases methane, a potent greenhouse gas, and VOCs that contribute to smog and can carry hazardous air pollutants. Flaring destroys most of the hydrocarbons but wastes the energy and still emits combustion products. Vapor recovery captures the stream instead.
A vapor recovery system collects vapors from the tank vapor space at very low pressure, typically ounces above atmospheric, through a manifold. The captured vapor is drawn into a compressor package that boosts it to a pressure high enough to inject into the gas gathering line for sale, or to use as on-site fuel. A control system holds tank pressure in a tight band so tanks neither over-pressure nor pull a vacuum.
Because tank vapor generation is variable, systems are sized and controlled to follow the load, and they often work alongside a flare or enclosed combustor that handles surges or takes over if the recovery unit is down. Instrumentation on tank pressure, compressor status, and flow is essential so that a loss of recovery is caught immediately and vapors are safely directed to backup control rather than released.
Vapor recovery delivers two benefits at once. Environmentally, it prevents the release of methane and VOCs, helping operators meet tightening federal and state air rules and voluntary methane-reduction commitments. Economically, the recovered vapor is saleable gas or free fuel, so a well-run system can pay back its cost through captured product that would otherwise have been lost.
The concept also appears beyond production tanks, at truck-loading racks and terminals, where vapor recovery captures the displaced vapors as tankers are filled. In every case the principle is the same: keep the hydrocarbons in the pipe, out of the air, and turn a would-be emission into recovered value.
Flaring burns hydrocarbon vapors, destroying most of them but emitting combustion products and wasting the energy. Vapor recovery captures the vapors intact and compresses them for sale or fuel use, so the hydrocarbons are recovered rather than destroyed. Recovery is generally preferred; flaring often serves as a backup for surges or downtime.
Three mechanisms at storage tanks: flashing, when liquid drops to tank pressure and releases dissolved light ends; working losses, from filling and emptying that push vapor out; and standing or breathing losses, from daily temperature and pressure changes. Together they produce a steady stream of light hydrocarbons and VOCs.
Operators watch tank pressure, compressor run status, and recovered-gas flow so any loss of recovery is caught before vapors are released. A cloud SCADA platform like Merobix can gather those points from field controllers over Modbus or MQTT and alarm on a stalled unit or a tank-pressure excursion, prompting a switch to backup control.
This page references the protocol specifications published by the organizations below. Editions, product capabilities, and documentation change over time - confirm current requirements and specifications directly with the source.
Last reviewed: July 27, 2026. Merobix is not affiliated with, endorsed by, or sponsored by these organizations; their names are used only to identify the standards and products discussed.
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