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The colour and shape of a flame provides a visual indication of how well a gas burner is performing and what adjustments may need to be made to achieve near complete combustion.
 

What is a ‘good’ flame?

A flame from a gas burner with a correctly adjusted fuel/air mixture should have the following characteristics:

• The flame should be blue;
• The flame should have two visible and well defined zones of combustion; and
• The flame should be stable on the burner

Near complete (or near perfect) combustion of a fuel/air mixture under normal atmospheric conditions will produce a good flame (Figure 1).  The products of combustion in this case constitute mainly heat, water vapour and carbon dioxide (CO2).

Causes of incomplete combustion of a fuel/air mixture (Figure 2) can include: lack of combustion air and flame chilling.
 

Lack of Combustion Air

When the combustion air supply to a gas burner is restricted, not enough oxygen will be present for the fuel gas (hydrocarbon fuel) to be completely oxidised (burnt) into CO2 and water vapour.  Instead, the partial oxidation of the fuel gas will result in the production of carbon monoxide (CO), soot (carbon) and possibly aldehydes.

Lack of combustion air can be caused by:

• Too much fuel-gas to the burner, causing a proportional reduction in the combustion air supply
• Poor burner adjustment or ventilation of the gas appliance
• A blocked or incorrectly sized flue, reducing the amount of fresh air available for combustion

Flame Chilling

Flame chilling occurs when solid objects interfere with the inner core of the flame causing the fuel-air mixture to fall below its ignition temperature thus creating a zone of incomplete combustion.

Products of Incomplete Combustion

Carbon Monoxide (CO)

Carbon monoxide is an odourless, tasteless, invisible and toxic gas that is the result of incomplete oxidation of fuel into carbon dioxide and water vapour.  Carbon monoxide is also a flammable gas and can be explosive under certain conditions.

Soot (carbon)

Incomplete combustion can produce solid particles of carbon in the flame.  It is these particles of hot, glowing soot that give a flame its yellow colour.  The particles cool as they escape the flame and deposit as black carbon on nearby surfaces.  Many authorities regard soot as a carcinogenic (cancer causing) substance.

Aldehydes

These are a class of organic compound formed during partial or incomplete combustion.  In high concentrations aldehydes are poisonous.  The production of aldehydes will produce a sharp, unpleasant odour and provides a warning that it is highly likely carbon monoxide is also present.  

Air and Gas Industries have been manufacturing liquified petroleum gas (LP Gas) road tankers since we opened in the 1970s.

Initially, LP Gas road tankers had a quite simple design with no electro-pneumatic automation.

Since the 1970s, road tankers have evolved to incorporate more electro-pneumatic automation of operating systems, leading to a more complex design with an increasing focus on safety.

Originally road tankers were made from carbon steel boiler plate, a thick and heavy material used for high pressure steel tanks.

This material has since been replaced by quenched and tempered steel, which reduced the thickness of the vessel from 16-20mm down to approximately 10mm. This decreased the weight of the vessel, reducing the tare of the vehicle and allowing for more gas to be transported.