Flame Colour Meaning
Flame colour can be indicative of temperature, type of fuel or the completeness of combustion. For example, a blue flame is the hottest followed by a yellow flame, then orange and red flames. Hydrocarbon gases burn blue whilst wood, coal or candles burn yellow, orange or red. A blue gas flame colour is also indicative of complete combustion.
Blue Flame Means Complete Combustion
A blue flame means complete combustion of the gas. With complete combustion, LPG (Propane) burns with a blue flame. Pure hydrocarbons like methane (refined natural gas), propane, butane and ethane gases also burn with a blue flame. These gases are all alkanes and are gas that burns with a blue flame.
LPG burns with a blue flame at a temperature of around 1,980°C. For Natural Gas (Methane), the blue flame temperature is about 1,960°C.
Adjusting the air (oxygen) supply affects the colour and temperature of the flame. Increasing air supply to the burner results in more complete combustion, less soot, a higher temperature and a blue flame colour.
Yellow or Red Flames Mean Incomplete Combustion
A orange, yellow or red flames means incomplete combustion of the gas.
A burner with a low air supply results in incomplete combustion process leading to sooty yellow or red flames and at a cooler temperature.
The yellow or red flames are due to incandescence of very fine soot particles that are produced in the flame.
This type of red flames only burns at around 1,000 °C ( instead of 1,980 °C for a blue LPG flame).
In addition to a yellow or orange flame, incomplete combustion of LPG Formula also results in hazardous carbon monoxide:
LPG Gas + Oxygen = Water + Carbon Dioxide + Carbon Monoxide + Heat with Yellow Flame
Propane Gas Furnace Flame Color
Propane gas furnace flame color is the same as propane flame color. Propane furnace flame color is a blue flame color on the flame color temperature chart, with complete combustion, and burns at a temperature of around 1,980°C.
Gas Fireplace Flame Color
Propane fireplace flame colour is typically yellow, as propane fireplace flame colour is designed to burn with a more natural look.
As wood logs do not burn with a blue flame colour, neither should a simulated wood fire. A propane fireplace needs yellow or red flames for a realistic look and feel. It is also engineered to operate safely with yellow or red flames, with a flue to eliminate indoor emissions.
Gas Cooker Yellow Flame – Are Yellow or Red Flames on Gas Stove Dangerous
A yellow or red flames on gas stove is dangerous, as it is indicative of incomplete combustion and carbon monoxide (CO) generation. A gas cooker yellow flame is a dangerous safety problem, if it occurs with an indoor appliance like a gas stove. You could also be wasting gas.
A gas cooker yellow flame means you should schedule a gas stove service as soon as possible.
Why is a Blue Flame considered Safer than a Red Flame?
A blue flame means complete combustion is taking place. A key warning sign that you require gas appliance servicing are yellow or red flames or a gas flame colour with a yellow burning tip.
Other indicators include the accumulation of yellow/brown soot around the appliance, pilot lights that frequently blow out or an acrid smell and eye irritation.
The exceptions to this are gas fireplaces and gas log fires that are designed to have a yellow or red flames. The above are all indications of incomplete combustion. The result is that you could be wasting gas and/or generating dangerous carbon monoxide.
The latter is a serious safety problem, if it occurs with an indoor appliance. If you observe any of these warning signs, you should schedule a service as soon as possible.
The burner should be cleaned and checked for proper operation.
Burners blocked with dirt can result in improper combustion, leading to soot build up inside the appliance.
Flames in Gas Oven – What Colour Flames in a Gas Oven
Flames in a gas oven should burn with a blue flame colour, meaning complete combustion, as with other gas appliances. Blue flame in gas oven applies to the flame color of propane or natural gas cooktops, as well.
Why do we see Blue Flames for LPG (Propane) and Yellow-Red Flames on Burning Wood?
The LPG (propane) is a blue flame because complete combustion creates enough energy to excite and ionize the gas molecules in the flame. The exception is a gas fireplace having yellow or red flames, for a more realistic look.
Burning wood has yellow-red flames due to incandescence of very fine soot particles that are produced in the flame.
Depending on the lighting, you may have actually seen the soot rising from the flame.
Combustion and Carbon Monoxide (CO)
All gas appliances, domestic and industrial, produce water vapour, Carbon Dioxide and heat, and usually very small amounts of Carbon Monoxide.
If installed and maintained correctly, the operation of the gas appliance provides quick and efficient heating, cooking, hot water and more, and the products of combustion do not create any hazardous situations.
If an appliance is not correctly installed and maintained or has been modified, the products of combustion might change, and become hazardous to the people around the appliance.
Something as simple as a ventilation change (getting fresh air to the appliance to sustain complete combustion) may cause a gas appliance to malfunction, and create a hazardous situation for the people around.
Sometimes it is obvious when a gas appliance malfunctions.
Sooty smoke, yellow or red flames or poor performance are indicators, but sometimes no indicators are obvious.
If Carbon Monoxide (CO) is produced and escapes the appliance into the surrounding air, it will not be obvious (no smell and no taste) but will be very dangerous.
It is essential that gas appliances are correctly installed and serviced every two years, to maintain good combustion and safe, efficient operation.
How Does a Blue Flame Colour Save Money?
A blue flame colour means complete combustion.
This indicates that the gas is being burned efficiently without any unburned and wasted gas.
With complete combustion you get the maximum heat output from your gas and use less gas to generate heat with whatever appliance you are using.
You also minimise or eliminate the creation of carbon monoxide.
So, now you know why a gas has a blue flame and why it’s a problem if it has yellow or red flames.
Keep an eye on your gas appliances and have them serviced, as needed, to keep them operating properly and safely.
Also follow the manufacturers’ recommendations for periodic routine servicing.
Your family will be safer and you’ll save money, too.