Class B
Fires involve flammable liquids. Typical flammable liquids are gasoline, oil, grease, paint, and acetone. Class B fires can be very difficult to control because they involve burning nonmetals in a liquid state. This classification also includes flammable gases. (Class B fires generally involve materials that Boil or Bubble.)
Electricity is not present in Class B fires. A Class B fire is extinguished with carbon dioxide (CO2) contained in a heavy cylinder and under pressure. CO2 is very cold when under pressure and displaces the oxygen around the fire, causing the fire to be extinguished. It should not be sprayed on people or animals. The use of a Class B extinguisher usually results in very little mess and no damage to property. However, avoid breathing CO2. Class B extinguishers may be used to extinguish both Class A and Class B fires. A Class B fire extinguisher is marked with a red square containing the letter B.
Class B is liquid fuel and Class C is gaseous fuel , as per ISO . Electrical is not considered as a class of fire but as a source of ignition.
As per NFPA (only American) class B is considered as liq/gas and class C as electrical.