Be Ready to Fight a Fire
A properly equipped and maintained suppression system can prevent an engine-room blaze from destroying your boat. "Hands-On Sailor" from our November 2009 issue
Fixed-Mounted Suppression Systems
Many boats are equipped with a fixed-mounted automatic fire-suppression system in the engine space. Because of their fixed nature, and the fact that they're essentially out of sight, people are likely to ignore the routine maintenance and checks that should be conducted to ensure that this equipment functions properly when needed.
These systems can vary in their sophistication, depending on the size of the engine room, which, on larger boats, may include other machinery, such as generators. Bigger boats, for example, may have a single extinguishing-agent bottle with multiple discharge nozzles that are plumbed using copper tubing. The multiple nozzles permit coverage of a more extensive area. Most modest-sized cruising boats, however, will have a single bottle and discharge nozzle near the engine; these closely resemble a standard fire extinguisher.
When it comes to the types of systems that get employed, I see a lot of non-compliance with current safety standards. A.B.Y.C. standard A-4, for example, requires that some mechanism be installed to allow the manual activation of an automatic extinguisher. In practice, however, many lack a manual override. Additionally, these systems are required to have a discharge indicator at the boat's primary helm location to let the helmsman know if the system has discharged. Often, though, these indicators are mounted on or near the engine-box cover, nowhere near the helmsman.
More problematic is this situation: To comply with the latest version of A-4, which went into effect on July 31, 2009, all diesel engines, both propulsion and generators, as well as engine-room blowers must shut down automatically in the event of an extinguisher discharge. Many boats out in the field don't comply with this standard, creating a very dangerous situation. This shutdown requirement is extremely important if the system is to do its job. Diesel engines consume large volumes of air when running and can easily consume your fire-extinguishing agent. Blower systems used to supply air or cool down engine-room spaces can also suck the agent out of the space. The bottom line here should be obvious: Your engine-room fire won't be extinguished.
A Look at Clean Agents
As for determining the size of the canisters used in fixed systems, the A.B.Y.C. standard doesn't provide guidance, but the system manufacturers certainly do, and sizing requirements can vary based on the types of fire-fighting chemicals being used. It's also extremely important to note here the differences between the FM-200 and FE-241 extinguishing agents, because here in the United States, both types are available and approved for use aboard sailboats. You should consider the pros and cons of each type, along with a third option, carbon dioxide. There are other agents available, but these are the three most popular.
Carbon dioxide: This mixture has been used for years and is an excellent choice for fighting Class B (flammable liquids) and Class C (electrical) fires. More commonly known by its chemical name, CO2, it functions by starving the fire of oxygen. Therefore, you should be careful not to enter a closed area where a CO2 extinguisher has been discharged until the area has been vented. Pound for pound, it's considerably less effective than either FM-200 or FE-241, so a greater weight of the agent will be needed to effectively extinguish a fire in a given area. CO2 won't leave any harmful residue on areas that have been exposed to it. Generally considered harmless to people, it's not considered environmentally friendly and is a primary greenhouse gas.
FE-241: The Environmental Protection Agency has approved FE-241 as a substitute for Halon, which is being phased out. Of the three agents mentioned here, FE-241 is pound for pound the most effective. However, this agent isn't approved for use in the European Union and isn't approved for use in areas of the boat that might be occupied by people, giving some insight into its potential toxicity.
FM-200: Also a Halon replacement, FM-200 is approved for use in either occupied or unoccupied areas by such entities as the National Fire Protection Association and Underwriter's Laboratory, but it's not specifically mentioned by the A.B.Y.C. The risk here, and probably one of the reasons that the A.B.Y.C. leaves this void in its A-4 standard, is that when exposed to a flame, the agent can decompose and form toxic hydrogen fluoride or carbonyl fluoride. It's often used in computer-server storage rooms, which may or may not be occupied. Relatively eco-friendly, FM-200 is probably the best choice for cruisers with global aspirations, as it's approved for use just about everywhere. Pound for pound, it's more effective than CO2 but less effective than FE-241.