Portable Fire Equipment Demonstation

This pictorial demonstration of the relative effectiveness of the following types of Portable Fire Equipment, when used on Class F fires involving deep fat fryers shows the importance of choosing the correct type of fire equipment for your requirements. Class F fires can be very difficult to extinguish, particularly if you do not have the correct Fire Equipment installed on your premises. The following fire equipment was used on the class F fire involving a deep fryer:

Fire Blanket
Carbon Dioxide Fire Extinguisher
Dry Powder Fire Extinguisher
Water
Wet Chemical Fire Extinguisher

The test apparatus used in this demonstration is intended to replicate the requirements of the fire rating standard AS/NZS 1850:1997. A Class 4F fire requires a one metre by half metre tray to be filled with 75 litres of Sunflower Oil and heated until auto-ignition occurs at a temperature of over 320^oC.

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Fire Blanket

The Fire Blanket initially appears to smother the flames and extinguish the fat fire. However, after a short period (maybe 20 seconds), the vapours from the oil saturate and suffuse through the Fire Blanket, and then begin to combust above the surface of the blanket (note the blanket itself does not catch fire). While the size of the fire has been reduced from the initial pre-burn period, it still poses a risk to the safety of people and property.

This demonstrates that a Fire Blanket, although effective against smaller Class F fires, cannot be considered ideal for protecting against a deep fat fire of this size.

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Carbon Dioxide

We then attempt to extinguish the same fire using a 3.5kg Carbon Dioxide type Fire Extinguisher. This type of Fire Extinguisher is ideal for installation to protect against Class E fires involving electrical risks.

Carbon Dioxide is not however, suited to extinguishing deep fat fires. While capable of �knocking down� the fires flames, the heat retained by the oil allows the fire to simply re-ignite. The �clean� nature of Carbon Dioxide in this instance is its inherent weakness, as it does not form a seal over the oil to prevent it from re-igniting.

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Dry Powder

Next we attempt to extinguish the fire using a 2.2kg ABE-Dry Powder Fire Extinguisher. Dry Powder type Fire Extinguishers are probably the most common type of Fire Extinguisher in use today.

The Dry Powder Fire Extinguisher appears to almost extinguish the fat fire, as the flames are knocked down. However, once the discharge from the Fire Extinguisher stops, the fire returns to its original intensity and continues to burn. As with the Carbon Dioxide Fire Extinguisher, the extinguishant's inability to form an effective seal allows the fire to continue to burn.

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Water

Water can be very dangerous if used on Class F fires involving fats and oils, as the photograph to the right produced by the New Zealand Fire Service demonstrates.

This reaction is caused by the huge amount of heat energy contained by the oil. As the heat energy contained by the oil is far greater than that which is required to evaporate an equivalent quantity of water, when added to the oil the water rapidly turns to steam, potentially creating an explosion.

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Wet Chemical

Next we attempt to extinguish the fire using a 3.5 litre Wet Chemical Fire Extinguisher. This type of Fire Extinguisher is easily capable of extinguishing a deep fat fire such as this.

The Wet Chemical Fire Extinguisher uses a chemical process called �saponification� to react with the fat and extinguish the fire. Here the reaction product between the extinguishant and the oil can be seen to cover the vat. The fire has clearly been smothered and the risk minimised.

The Wet Chemical Fire Extinguisher is the ideal type of Fire Extinguisher for installation to protect against this type of risk. Other types of Fire Extinguisher, while effective on other Classes of Fire, are not considered effective on Class F fat fires such as this.

The demonstration clearly shows the vital importance of selecting the correct type of Fire Protection Equipment for your requirements. We, as your fire protection specialist can make this selection process simple and safe.

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