Portable, handheld fire extinguishers have to be USCG approved but how do you know which approved extinguisher you should use? Fire extinguishers contain different extinguishing agents and are labeled so that you know which one is best for the particular type of fire you have.
Depending upon the type of fire you may have on board, you will need to use an extinguishing agent that is appropriate.
Below are the most common types of fires found on board a vessel:
Class A fires are combustible solids such as wood, fiberglass, cloth, etc. (Think "ASH" for solids)
Class B fires are flammable liquids such as gasoline, diesel, etc. (Think "Boil" for liquids)
Class C fires are electrical (Think "CURRENT" for electrical)
There is actually another, more uncommon classification, "D" for metal or molten fires. However, we will focus on the type of agent you will use on common fires found on a vessel:
Carbon Dioxide (CO2)
Carbon Dioxide is a class B, C, agent only. Because of the CO2 high pressure, it is not recommended for use on Class A, amber and ash based fires. Why? Because of the hazard of spreading the fire when blasting it with the high pressure gas.
Dry chemical extinguishers come in three varieties:
Sodium Bicarbonate B, C (Alkaline)
Potassium Bicarbonate, Purple "K", B, C (Alkaline);
Mono Ammonium Phosphate A, B, C (Acidic). The A, B, C dry chemical is not recommended for marine use for two reasons: It is corrosive. The way in which this agent obtains it class A rating is its ability to melt, seep and encase. This necessitates dismantling of equipment to repair or rebuild.
Foam extinguishers are water based and quench Class A fires. They also blanket, smother and
separate the vapor layer in Class B fires.
Be sure you have the appropriate fire extinguisher that can fight any of these 3 common classifications of fires on board your vessel.