The Water Seal provides a positive means of flashback prevention in addition to enabling the upstream system header to operate at a slightly positive pressure at all times.

This is especially of use when an elevated flare is used in combination with another flare or with a flare gas recovery system.

The GBA Water Seal design incorporates advanced features to ensure smooth gas flow without pulsation.  These features have been successfully retrofitted to existing equipment to solve pulsation problems.


Knock-Out Drums are designed to effectively remove hydrocarbon liquids from the main flare relief gas to prevent the possibility of liquid carryover and flaming rain from the flare tip.

The size of the Knock-Out Drums is based on the criteria defined in API RP 521 considering residence time and knock out the velocity of the liquid particles in the vapour flow. Although flare tips can handle small amounts of liquid droplets, the allowable velocity in the drum may be based on that necessary to knock out droplets from 300 microns to 600 microns in diameter.

The drums are designed to avoid the accumulation of hydrocarbon liquid and will be equipped with instrumentation and control to monitor liquid levels with pump out or any drain facilities.


To prevent air ingress into the riser two types of seals can be provided: a Molecular Seal bolted below the flare tip or an Air Lock Seal (Velocity type) within the flare tip.


The Molecular Seal works by relying on the density difference between the purge gas and air. In this way, only a very low continuous purge flow is necessary to maintain conditions within the seal.

The Molecular Seal maintains safe conditions in the upstream riser for several hours in the event of a loss of purge gas.


The Air Lock Seal (ALS) is a cone device located as an integral part of the flare tip.  When a flare tip operates with very low flare gas flows, air will tend to enter the tip due to both wind action and by decantation and will slowly diffuse down the inside walls of the tip. The Air Lock Seal design locally increases the velocity of purge gas through the seal, thereby moving any air back out of the tip.

GBA install Air Lock Seals in all flare tips to minimise purge gas consumption and maximise flare tip operating life.


The automatic control of steam flow to a smokeless flare can be achieved by the use of a remote infrared sensor, which detects flame density changes in the hydrocarbon flames and provides the process variable signal for steam control allowing only the correct amount of steam necessary for the required smokeless capacity.

Alternatively, ultrasonic flare gas mass flow meters can be employed to control the steam flow.



GBA offers state of the art LED-based Aircraft Warning Lights that offer the prospect of never needing replacement/attention. These units are available in Medium (Red or White) and Low Intensity (Red only) format.

When conventional lights are used, GBA has developed a unique demounting system specifically designed for flare stack applications which enables replacement from grade, without shutting down the flare.