I have been told by a friend that I need a wet chemical extinguisher for my new business (a chip shop). Is he right?

He/she is, the only suitable fire extinguisher for cooking fat fires is wet chemical. Tests have established that a 6 litre wet chemical extinguisher is capable of extinguishing a fire in a 75 litre capacity deep fat fryer, a simple calculation to work out how many extinguishers you need.

Check out http://www.firesafe....uisher-general/ and http://www.firesafe....-extinguishers/ for more information.

Hi, Can anyone advise how to work out what size and how many wet chemical extinguishers are required please?

Extinguishers suitable for Class F fires (cooking oils) such as Wet Chemical & Water Mist have a Fire Rating that determines the size of fire the extinguisher can tackle based on litres of oil involved - an extinguisher with a 5F rating has extinguished a 5 litre cooking oil fire, a 75F rating is 75 litres.

This is more important than size of extinguisher as different manufacturers extinguishers get different ratings, e.g. one brand of 2 litre Wet Chemical is 25F rated, but another gets a 40F rating allowing it to be used on a bigger fire.

The traditional rule of thumb was the rating of the extinguisher should exceed the maximum volume of oil in the biggest fryer, however BS5306-8, the standard for extinguisher provision advises the use of the area of the exposed surface of the fryer against the attached table: