A pan of boiling oil that is on fire is extremely difficult to extinguish. Water, which is what we normally use to put out a fire, is the last thing you should use here. So what should you do?
Never leave a deep fat fryer or a pan of hot fat unattended. If it catches fire, you only have a few minutes to put it out. This is why you should always have a lid or fire blanket handy when you intend to deep fry food.
If you discover the fire quickly, you can cover it with a lid or fire blanket to smother the flames. You should also be aware that hot oil can re-ignite, even if you think you have extinguished the fire.
If the fire has already taken hold, approaching it with a lid or blanket is difficult and dangerous. The oil can also boil over after only a few minutes, which will spread the fire across the work surface and floor.
Some hand-held extinguishers have been specially developed to put out fat and grease fires. Tests have shown that, unlike ordinary fire extinguishers, these are effective at extinguishing deep fat fires and preventing them from re-igniting. If you do a lot of deep fat frying, you should consider keeping one of these special extinguishers handy in the kitchen. You can buy them at hardware shops and DIY stores.
Water and hot fat do not mix. If you try to put out a hot fat fire with water, you will create an explosive fireball. This is why you should never use water to put out a deep fat fire.
Tests have shown that ordinary hand-held extinguishers filled with foam, powder and CO2 are ineffective at extinguishing fires involving vegetable oils. The pressure in these extinguishers, particularly powder extinguishers, also tends to be so high that it forces the burning oil out of the pan. This then causes the fire to spread.