Not at all. Covered under Class B fires are a variety of fuels and situations. If you look in NFPA 10, Class B fires are divided into several categories.

Pressurized Flammable Liquids

Pressurized Flammable Gases

Three Dimensional Class B Fires

Water Soluble Flammable Liquid Fires
       (Polar solvents)

Flammable Liquid Fires of
       Appreciable Depth

Class B Fires Other than Appreciable
       Depth

Each one of these categories represents different agent application technique, different types of extinguishers and different methods of extinguishing the fire. The only UL test fires are Flammable Liquid Fires of Appreciable Depth using N-Heptane as fuel.

Fires involving Pressurized Flammable Gases usually should NOT be extinguished unless the fuel source can be shut off (if these fires are extinguished and gas is allowed to flow a greater hazard will be created).

Kitchen Grease Fires are now a separate class of fire - Class K per NFPA 10, 1998 edition.

We will discuss each of these situations in different Guides to Hand Portable Mythology. Some of this was discussed in “Common Myth #2” which dealt with agent flow rates.