VESSEL CONSTRUCTION, VENTILATION, AND FIRE MAIN
Fighting a fire aboard a ship is akin to lighting a fire in a high-rise building in the respect that a fire officer must utilize construction features and internal systems to locate, reach, confine, extinguish, and ventilate a Fire. Construction may have to be used to protect occupants in areas of refuge, as it is practically impossible to completely evacuate everyone in a short period of time.
The most important aspect of the ship’s construction in this scenario was the locations of the main bulkheads. Main transverse bulkheads enable a ship’s hull to withstand the forces of rough seas as well as to capture flooding water in a limited area. Certain bulkheads also are firerated to confine the spread of fire to a manageable area, in the way a firewall would confine fire spread in a building. Openings in bulkheads are protected by watertight doors on lower decks and fire screen doors in the superstructure. The locations of rated bulkheads and openings have a great impact on where a fire is conlined, where a fire will be attacked, how it is to be ventilated, and how rescue operations will progress.
The most punishing approach to a fire on a lower deck is one that is within the same vertical zone; firelighters will be forced to endure heat and smoke rising in the same path they are using to reach the fire. Passengers, especially the elderly, will have a difficult climb up smoky stairs to a weather deck. To avoid rising heat and smoke, a basic tenet of marine firefighting is to reach a fire by descending in an adjacent vertical zone, i’he fire then can be attacked at its same level through a watertight door opening. Passengers can be moved laterally to the protection of an adjoining zone, using the compartmentation afforded by firerated bulkheads.
Because the lower decks of a ship have very few openings for natural ventilation, they depend on powerful air-handling systems to exchange air. A ship’s ventilation system can have a strong influence on the spread or confinement of fire and its products of combustion. When a fire is discovered aboard ship, standard procedure initially is to shut off ventilation fans and close dampers serving the tire zone. This action limits the supply of oxygen to the fire and reduces the chances of fire communicating by ductwork. Controlling ventilation system fans and. possibly, dampers usually can be accomplished from the bridge and other remote locations. Dampers can be closed manually where a duct penetrates a bulkhead separating fire zones. Fire conditions and ventilation system design may indicate that air supply continue in uninvolved zones; this has the effect of creating a positive-pressure gradient that restricts the passage of smoke out of the tire zone.
FIRE MAIN SYSTEM
A ship is equipped with a fire main system, which is similar to a standpipe in a building. The system consists of fire pumps, piping, isolation valves, fire station outlets, hoses, nozzles, and fittings. A large ship has several fire pumps that take suction from the sea. On some ships, bilge and ballast pumps also can be put on line to supply the fire main, Emergency fire pumps are required to be located in a separate fire zone and receive power from the ship’s emergency circuits.
Piping branches out to supply outlet stations throughout the ship, similar to a Class 11 standpipe. Outlets arcspaced so that all sections of the ship can be reached with one section of hose from the closest outlet. The location of each outlet is detailed on a ship’s fire control plan. The types of hoses, nozzles, and couplings connected to fire main outlets depend on where the ship was built; American threaded couplings are a rarity.
Some fire departments, by policy, prohibit the use of a ship’s fire main; firefighters use only fire department hose supplied by fire department apparatus. This regulation is well founded; fire mains are notorious for delivering insufficient pressure and volume. Nozzles can clog from years of accumulated sediment. Is it wise to rely on a system of a ship that is already in trouble?
There are, however, distinct advantages to using the ship’s fire main system; It allows for the fastest and most direct attack on a fire with a minimum of hose. In contrast, stretching from a shoreside pumper can be very time-consuming and personnel-intensive. Actual ship fires have required several hoselines, hand-laid hundreds of feet, to attack the fire and cool boundaries.
Our department permits the use of a ship’s fire main system with the following stipulations:
- Pressure and volume are augmented by fire department pumpers. Pumping into a fire main is facilitated by an international shore connection, which is required on ships so that they can be supplied by a shoreside pumper anywhere in the world. The ship’s flange connection bolts to a mating flange connected to hose from the shoreside. The inlet of the shoreside connection has the hose couplings of the local department.
- Fire department hose should be used in favor of a ship’s hose. We have made several adapters by attaching the ship’s hose couplings to three-foot sections of our hose. The adapters facilitate connecting our high-rise hose packs to couplings from Europe, Asia, and the U.K.
- Never commit personnel to positions where their safety depends on a fire main system. A quick attack from a fire main is ideal for a fire in one or two staterooms; it may be no match for an advanced fire involving a large area.