AFFF Portable Extinguishers Are Designed for Class Bravo Fires

AFFF and the right fire fighting tool for the job

If you’ve ever stood on a pier or in a ship’s engine room and watched someone fight a fire with foam, you know there’s more to safety than grabbing any extinguisher and hoping for the best. On a vessel, the tools you choose matter as much as the training you’ve logged. One of the most important distinctions is knowing which extinguisher to pull when a flame isn’t just flames—it's a liquid fuel flame. That’s where the AFFF portable extinguisher comes in, and why it’s specifically matched to Class Bravo fires.

What makes a Class Bravo fire different

Think of Class Bravo fires as the “liquid heat” fires. They involve flammable liquids like gasoline, oil, solvents, and certain greases. These fuels can pool on a surface and, even if you snuff the visible flames, vapors can keep reigniting the fire. That’s a dangerous dynamic aboard a ship, where fuel lines, ballast tanks, and galley stations are always nearby. Water by itself can spread some of these liquids or cause a dangerous splash—so you don’t want to treat every fire with the same tool.

AFFF: how it works, in plain terms

AFFF stands for aqueous film-forming foam. When you deploy an AFFF extinguisher, the foam forms a film on the surface of the burning liquid. That film does a couple of crucial things:

• It blankets the fuel, cutting off the oxygen that feeds the flames.

• It suppresses the release of flammable vapors, which helps prevent re-ignition.

• It cools the liquid’s surface, slowing the fire from spreading.

In short, AFFF doesn’t just smother the flame; it buys time by keeping vapors down and the fuel from flashing up again. That combination is exactly what you want when you’re trying to control a slick, reactive fire in a confined space.

Using an AFFF extinguisher on a boat or ship

Here’s where the practical, hands-on part comes in. You’re not just waving a canister around; you’re executing a sequence that minimizes risk and maximizes the chance of putting the fire out.

• Pull, Aim, Squeeze, Sweep (the classic PASS method)

• Pull the pin to break the tamper seal.

• Aim at the base of the fire, not the flames themselves.

• Squeeze the handle to release the foam.

• Sweep the nozzle from side to side, covering the fuel surface.

• Stay low and keep your distance

• AFFF works at the surface, so you’ll want to stay a bit above the rise of the pool and push foam toward the fuel spill. If the liquid is running toward a bulkhead, adjust your sweep to keep the film on the pool.

• Get the right angle and tempo

• Start at the edge of the pool and work inward. A gentle, continuous sweep is usually better than short bursts, especially with a small portable extinguisher. You’re trying to lay down a continuous foam blanket, not just a short white puff.

• Don’t forget the drain and ventilation

• In an enclosed space, vapor buildup can sneak up on you. If you can safely do so, open a vent or move the source of the vapors so the foam isn’t fighting a contained, gassy environment.

• Know when to retreat and call for reinforced help

• If the fire is spreading or there’s heavy heat and smoke, evacuate and summon more equipment and trained personnel. Foam can slow a blaze, but it isn’t a miracle cure in every scenario.

Why AFFF is the go-to choice for Class Bravo on ships

AFFF’s advantage lies in its dual action: it smothers and cools. The foam film blocks oxygen and reduces vapor release at the same time, which is exactly what you want when the fuel is slick and the area is tight. It’s less effective on some other kinds of fires, which is why you don’t use the same extinguisher for every class.

Class Alpha, Charlie, and Delta—a quick contrast

• Class Alpha (ordinary combustibles like wood and paper): water-based extinguishing methods are most common. Water helps cool and saturate the material, but it isn’t a one-size-fits-all solution, especially on a ship where the material mix can surprise you.

• Class Charlie (electrical fires): electricity is a wild card. You want to minimize current flow and avoid water on live circuitry. Dry chemical or CO2 extinguishers are often safer choices in these situations.

• Class Delta (reactive metals like magnesium): you’re in a different ballgame. Specialized agents are required, and typical foam or water don’t cut it.

On a naval vessel, recognizing the right class and the corresponding extinguisher isn’t just good practice—it’s a matter of safety and mission readiness.

Foam, safety, and the environment

AFFF isn’t just about fire suppression; it’s also about how foam interacts with a ship’s crew and the environment. In recent years, attention has grown around the environmental footprint of foam concentrates. That means maintenance crews closely monitor concentrate quality and expiration dates, ensuring the foam blanket remains effective when you need it most. It also means training sailors to understand when foam is the correct tool and when alternatives should be considered.

A quick note on limitations

No extinguisher is a magic wand. AFFF works best on surface burning liquids and when you can apply it quickly to form a bridging layer on the fuel. If the fuel is rapidly expanding, or if the fire involves more than a surface film—say, the liquid is spraying or the flames have engulfed a large area—the fire might outpace your first response. In those moments, communication, evacuation plans, and crew coordination become just as important as any tool in hand.

Reading the room like a seamanship pro

A big part of naval safety is reading environments and anticipating how fires behave in the ship’s unique settings. Engine rooms with hot machinery, pump rooms with flammable lubricants, and storage decks with fuel containers all demand a practiced eye. The AFFF extinguisher is a critical piece of the kit, but it works best when you pair it with good spacing, quick assessment, and a calm, methodical approach.

Keeping the kit shipshape

• Regular inspections: check the pressure gauge, hose, nozzle, and the tamper seal. If anything looks off, tag it and report it.

• Hydrostic testing: schedule the testing of extinguishers per the applicable maritime regulations. A failed test is no small thing.

• Accessible placement: foam extinguishers should be placed where fuel spill risk is greatest, yet accessible to the crew tasked with rapid response.

• Training and drills: hands-on familiarity with the tool—how to grab it, how to aim, and how to work with the crew—makes a real difference in real incidents.

Relating it back to PMK-EE E4 Seamanship knowledge

In seamanship, you’re constantly balancing theory with practice. Understanding that a Class Bravo fire calls for an AFFF extinguisher isn’t just trivia; it’s a practical framework for quick, confident action. It’s knowing which tool fits the job, when to deploy it, and how to coordinate with fellow crew members to keep everyone safe. The more you relate each tool to a real scenario aboard a vessel—engine room hot spots, a galley fryer flare-up, a spilled aviation fuel on a deck—the more natural it feels to make the right move under pressure.

A short tangent that slots back to the main point

Here’s a little analogy to keep in mind: think of a foam blanket as a temporary peace treaty between the flames and the fuel. The burn zone settles, vapors stop roaming, and you have time to work. But treaties can break when you rush in without a plan or when you pick the wrong envoy (in this case, a different extinguisher). That’s why training, routine checks, and clear communication matter as much as the foam itself.

A few practical takeaways to hold onto

• Remember Class Bravo fires need a liquid-focused solution. AFFF is designed for those situations.

• Learn the proper application technique: pull, aim at the base, squeeze, sweep.

• Don’t treat every fire the same way. Class Alpha, Charlie, and Delta demand different approaches.

• Keep the extinguisher in good shape and within reach, and stay current on crew training and drills.

• Pair the tool with a calm, practiced response plan. In a ship’s tight spaces, nerves can run hot—your method can cool theroom as much as the foam does.

Closing thoughts

Fire safety on the water isn’t a flashy show of power; it’s a discipline of knowing the right tool for the job, deploying it with care, and staying with a plan long enough to keep the crew safe. The AFFF portable extinguisher embodies that discipline for Class Bravo fires—liquids that love to spread and vaporize. By understanding why this extinguisher is the best fit for those flames, you’re not just memorizing a fact; you’re building a reliable, practical habit that can save lives and vessels.

If you’re coordinating on-shift safety or planning drills, keep this in mind: a well-placed AFFF blast can buy precious seconds, creating space for safe response. And across every deck, in every hold, the ability to pair knowledge with action is what makes a crew resilient, capable, and ready for anything the sea throws their way.