<Li> Class E fires involve electrical equipment / appliances . </Li> <Li> Class F fires involve cooking fat and oil . </Li> <P> Class E has been discontinued, but covered fires involving electrical appliances . This is no longer used on the basis that, when the power supply is turned off, an electrical fire can fall into any of the remaining five categories . </P> <Table> <Tr> <Th> Type </Th> <Th_colspan="2"> Old code </Th> <Th> BS EN 3 colour code </Th> <Th_colspan="6"> Fire classes (brackets denote sometimes applicable) </Th> </Tr> <Tr> <Th> </Th> <Th> </Th> <Th> </Th> <Th> </Th> <Th> </Th> <Th> </Th> </Tr> <Tr> <Td> Water </Td> <Td> Signal red </Td> <Td> </Td> <Td> Signal red </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Foam </Td> <Td> Cream </Td> <Td> </Td> <Td> Red with a cream panel above the operating instructions </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Dry powder </Td> <Td> French blue </Td> <Td> </Td> <Td> Red with a blue panel above the operating instructions </Td> <Td> (A) </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Carbon dioxide, CO </Td> <Td> Black </Td> <Td> </Td> <Td> Red with a black panel above the operating instructions </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Wet chemical </Td> <Td> N / A </Td> <Td> </Td> <Td> Red with a canary yellow panel above the operating instructions </Td> <Td> </Td> <Td> (B) </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Class D powder </Td> <Td> French blue </Td> <Td> </Td> <Td> Red with a blue panel above the operating instructions </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> <Tr> <Td> Halon 1211 / BCF </Td> <Td> Emerald green </Td> <Td> </Td> <Td> No longer in general use </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> <Td> </Td> </Tr> </Table>

Explain the purpose of the following fire extinguishers water