Risks of Class B Fires
When flammable liquids and gases catch fire, they spread extremely fast. The Collins English Dictionary defines an explosion as "a violent release of energy resulting from a rapid chemical or nuclear reaction, especially one that produces a shock wave, loud noise, heat, and light." Fire with Class B materials is exactly that, a rapid chemical reaction of the fire triangle with heat and light. Class B fires also have a higher potential for flashback. That is when invisible vapors ignite and travel back to the source. While ordinary combustible fires give off fumes, the fumes from flammable liquid fires are particularly toxic, especially where ventilation is poor.
Class B Fire Extinguishers
Many Class B extinguishers, like foam fire extinguishers or dry chemical extinguishers will use a messy and corrosive extinguishing agent that can cause just as much (if not more) damage as the fire. Element fire extinguishers will extinguish Class B fires fast without the toxic mess.
Never Use Water
Water will make the fire worse. When you put water into oil, it causes the oil to separate and spread out. The same thing happens when using water on a Class B fire but those blobs are flaming and will spread the fire!
What Is the difference between a Class B Fire Extinguisher Rating and a Class K Rating?
Each fire extinguisher is labelled with the fire classes it can be used for. There are many ABC extinguishers but very few can also be used for Class K fires. Class K fires are similar to Class B as they both involve flammable liquids. Class K fires deal specifically with cooking oils and fats which tend to be denser so a pressurized Class B extinguisher could drive the fire deeper into fuel, making it worse. The extinguishing agent from extinguishers rated for K fires are expelled without thrust so they won't make the fire worse. Element is rated for A, B, C & K fire classes.