Chip pan

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A demonstration of a chip pan fire by the North Yorkshire fire service
A demonstration of a chip pan fire by the North Yorkshire fire service

A chip pan is a deep-sided cooking pan used for deep-frying. Chip pans are named for their traditional use in frying chips (french fries).

Today, they are made from either aluminium or stainless steel, although in the past were commonly made from cast iron. A basket is placed inside the pan, to lower the chips into the hot cooking oil, and to raise them once cooked.

Chip pans are commonly used in the United Kingdom, although are slowly being outmoded by deep fryers. They are well known for being a fire hazard.

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[edit] Chip pan fires

Laboratory simulation of a chip-pan fire: a steel beaker containing wax is heated over a Bunsen burner until it catches fire. A small amount of water is then poured into the beaker. The water sinks to the bottom and vaporises, ejecting a plum of burning molten wax into the air.
Laboratory simulation of a chip-pan fire: a steel beaker containing wax is heated over a Bunsen burner until it catches fire. A small amount of water is then poured into the beaker. The water sinks to the bottom and vaporises, ejecting a plum of burning molten wax into the air.

The two main causes for chip pan fires are:

  • The oil or fat overheats and catches fire.
  • The oil or fat spills onto the cooker, either because the pan has been filled too high; or because wet chips are put in the hot oil, causing it to bubble up and overflow.

Chip pans are the most common cause of house fires in the United Kingdom, with around 12,000 chip pan fires every year, with 1,100 chip fires being considered serious. These fires result in over 4,600 injuries, and 50 deaths per year. British Fire Brigades frequently issue warnings and advice, urging households to switch to a safer means of cooking chips, and advising that unless the fire is easily contained to leave the fire to the emergency services.[1]

Cooking oil fires (US class K, Europe class F) burn hotter than other typical combustible liquids, rendering the standard class B extinguisher ineffective. Class F fire extinguishers use saponification to put out chip pan fires by spraying an alkaline solution which reacts with the fat to make a non-flammable soap. However, these extinguishers are generally only available in industrial and commercial kitchens.

[edit] Cause of fires

The following sequence of events results in an "explosion" (deflagration, not detonation):

Oil gets so hot that it catches fire all by itself

Water is poured into the burning chip pan

Water is denser than oil, so it sinks to the bottom of the chip pan (shown in red). As the water touches the bottom, it is heated above its boiling point and instantly vaporizes

The water vapour expands rapidly, ejecting the burning molten oil out of the chip pan and into the air where its surface area increases greatly and combustion proceeds much faster

Oil is heated strongly

After some time, it gets hot enough to catch fire

Pouring a very small amount of water into the fire ejects a plume of burning oil

With all the oil burned, there is no more fuel to supply the fire

[edit] References

  1. ^ UK Fire Service advice on chip pan fires

[edit] External links