Fires aboard ship in World War II were fought by damage control teams applying water and protein foam. Hand-held CO 2 extinguishers were widely used, and overhead water sprinklers were also employed in confined spaces and aircraft carrier hangar decks.
Steam smothering systems were available in some ships to handle engine room bilge fires. The emphasis in fire fighting was to attack fires directly with men manning hoses dispensing solid water streams or fog, and this remained the accepted approach during the immediate postwar years. In the late s, a series of aircraft carrier fires incident to Vietnam War operations triggered a search for more effective ways to fight massive flight deck fires.
Fighting fires aboard carriers, while always challenging, had become more so in the age of jet aircraft, which carried ten times as much fuel and ten times the weight of explosives as had predecessor aircraft in World War II. As a result, aqueous film-forming foam AFFF was introduced as an effective replacement for protein foam, and it became the primary agent in fighting flight deck fires.
Flush deck nozzles were installed to dispense AFFF on demand to deal with pooled area fuel fires. Additionally, small twin-agent flight deck tractors were equipped with small amounts of AFFF and PKP for quick-reaction fire suppression. Twin-agent hoses also began to appear in ship machinery spaces mounted on reels for ready access by engine room personnel. Despite these advances, a flammable fuel fire with vertical dimensions remained a fire fighting challenge, as did the pressure-fed engine room fuel spray fire.
And in the late s, machinery space. A variety of technical approaches were considered that would make possible quick evacuation of a machinery space, followed by remote actuation of the fire extinguishing system.
After a rigorous selection process and substantial testing in the early s, halon was chosen as the optimum total flooding agent for ''abandon-the-machinery-space'' fires. The first halon systems were installed in aircraft carriers and mine craft in A policy was established calling for installation of halon in new-construction ships, such as the FFG-7 class frigates, and selective retrofitting into older vessels began on an age-selective basis.
Engine rooms also were equipped with AFFF bilge flooding systems. And although the principal reason for acquiring halon systems was to fight machinery space fires, halon 's attraction as a very effective, non-toxic agent resulted in its being substituted for CO 2 in other spaces where flammable liquids were stored. This introduction of halon to the Navy followed its earlier acceptance for total space flooding applications in the civil community.
Thus, because of a confluence of events—availability and civil acceptance of halon , an urgent Navy need for a better agent, and top-level support—halon became the agent of choice for coping with fuel spray fires in confined spaces. Use of halon enabled the Navy to adopt a casualty-reducing tactic of 1 taking the man out of the loop initially by abandoning the fire scene, 2 remotely actuating the halon flooding system, and 3 reentering the space when the fire was extinguished to deal with any minor residual flare-ups.
Halon has only limited application aboard ship. It replaced PKP in fire trucks aboard aviation ships in the late s for fighting three-dimensional fires. The agent is also used in mine craft MSCs and air cushion landing craft LCAC , and there are a few hand-held bottles to be found in certain other ship classes.
Fires in aircraft have been a major concern since the inception of powered flight in the early s. The very nature of aircraft—being airborne, carrying large amounts of flammable liquids, containing potential ignition sources—makes them inherently vulnerable to loss if fire should break out.
Hence, fire prevention is a major consideration in aircraft design, as are fire extinguishing systems tailored for the specific plane and its anticipated operating environment. Since most fires start in inaccessible areas, particularly in military tactical aircraft, extinguishing them must depend on automatic or remote activation of extinguishing systems.
And as mentioned above, combat aircraft have the additional challenge of coping with damage that may be inflicted by enemy antiaircraft artillery and missiles.
Early combat loss experience in World War II highlighted the vulnerability of tactical aircraft to loss by fire and explosion. Self-sealing fuel tanks were installed to reduce the probability of leakage if hit, with the resultant fumes causing explosions in void dry bay areas.
Additionally, attention was paid to placement of fuel lines and shielding components. CO 2 fire extinguishing systems were installed in the nacelles of multiengine aircraft, as they were in civil airliners of the time. The introduction of jet aircraft into the Navy in the s was accompanied by a change in strategic emphasis toward nuclear warfare. Attack aircraft were designed to fly long ranges, while designers tried to exact maximum speed and altitude performance from fighters. In the quest for performance, the vulnerability of planes to combat damage, including fire and explosion, was accorded low priority during aircraft design.
Even in the case of rotor craft that fly slowly at low altitude, little attention was paid to measures that might reduce vulnerability to loss if the helicopter was struck by enemy projectiles or small missiles. During the Vietnam War the United States suffered combat losses totaling aircraft— fixed-wing jets and helicopters. As losses mounted during the course of the conflict, studies were initiated to see what might be done to lower loss rates, an effort that continued after the war.
As a result, the military services joined in an effort to improve the survivability of jet aircraft and helicopters. Technologies considered were 1 solid foams, powders, and inert gas generators for dry bays; 2 solid foams and inert gases for fuel tank ullage areas; 3 halon for engine nacelles and bays; 4 portable halon bottles, principally , for occupied areas; and 5 AFFF and halon for crash fire fighting and small fires incident to engine start.
The adoption of halons and was the culmination of fleeting military involvement with halons over the years. In the s non-fluorinated halon agents were tried experimentally in engine nacelle extinguishers, but their use was abandoned by the U. Despite their relatively high inhalation toxicity, systems using halon , , and were developed during World War II and employed by the British and Germans in military aircraft.
The use of these agents expanded into the civil sector after the war. In the United States, however, it was only after development of fluorinated halons , that CO 2 was replaced in Air Force and Navy aircraft by these new highly effective, less toxic, and non-corrosive agents. And since they had already gained some acceptance in U. Fire at sea has always posed a special danger. In warships, the fire hazard is exacerbated by the threat of explosive weapon warheads and propellants.
Throughout its history the Navy has dealt with fire protection challenges by exacting the most from existing fire fighting systems through organization and training as well as by exploiting new technologies.
The exploitation of dry chemical powders and aqueous film-forming foam as well as the introduction of specialized naval fire fighting systems are examples of the constant improvement sought by the Navy in the safety and survivability of its vessels, aircraft, and crews. Employing halons for machinery space and aviation fire extinguishing applications is an example of adopting new technology to improve fire protection.
The principal fire threats in machinery spaces are the combustible liquid pool and pressurized spray fire. The most hazardous type of incident, and one that absolutely requires a gas-phase fire suppressant, is the three-dimensional spray or cascading fire. These fires arise from fuel or lubricant pipe or fitting leaks, human error, or mechanical damage. Leaks can vary in scale from less than 1 to greater than 50 gallons per minute.
Pressurized spray fires generally occur in fuel, lubricating oil, or hydraulic fluid system piping. Pressures range from 10 to psi. Non-pressurized cascading fuel fires often involve sounding tubes, gravity storage tanks, and fuel piping that transit the space servicing other areas such as aviation fuel systems. In general, a spray or cascading fuel fire will also produce a pool fire. A release of fuel or lubricating oil can be quickly ignited by hot surfaces steam pipes or boiler fronts , electrical arcing or shorts, welding operations, and mechanical sources friction, sparking, and so on, related to equipment failure.
The intensity of these fires can easily approach MW power equivalent. The fire growth time scale is on the order of several seconds, so that very large fires, high temperatures, and fatal concentrations of carbon monoxide CO can occur in 30 seconds or less. Since there is insufficient oxygen to maintain a large fire, the power level will decrease with time, and higher CO production will occur. The size and growth rate of these three-dimensional fires preclude safe reliance on manual firefighting in closed spaces.
Clearly, manual fire fighting against a large machinery space fire is not the approach of choice because of the rapidity with which the space becomes untenable due to heat, smoke,.
Indeed, these hazardous conditions are the very reason halon was introduced in the Navy some 20 years ago. Reignition is also a key consideration in fighting machinery space fires. Three sources of reignition in ship machinery spaces—hot surfaces, electrical sources, and smoldering solid combustibles—form the basis for the required agent hold times and reentry procedures. Each source of reignition is described briefly below.
Three systems are employed to control or extinguish fires in machinery spaces. The total flooding halon system is the key element of a three-element overall system of fire protection. It is capable of extinguishing any flammable or combustible liquid fire, pool or spray, as well as solid combustibles ignited as a result of the liquid pool or spray fire.
Halon is used when a fire is too large to suppress manually, which is usually the case with pressurized spray fires. Additional fixed protection in machinery spaces is offered by the AFFF bilge foam system.
It is designed to extinguish pool fires caused by fuel or lubricating oil leaks and to prevent reignition. Take a look at our frequently asked questions below. This is the most effective extinguishing agent available. Halon is a clean agent, which means it leaves no residue when used, so it causes no damage to your property.
The use of Halon is not banned, but rather the manufacturing of Halon globally, because of its Ozone Depleting properties. In the Montreal Protocol found Halon was damaging the environment. Halon is still used in many applications. From protecting computer rooms throughout the electronics industry, to numerous military applications on ships and even on commercial aircraft, Halon is an integral and unparalleled fire-extinguishing agent.
Contrary to popular belief, Halon does not remove oxygen from the air, but rather reacts with all elements of a fire. When Halon is discharged, it breaks the chemical chain reaction.
This accounts for most of its fire fighting properties. The other properties come from the cooling effect of the expanding gas. Because of this, Halon can be safely used in an occupied space. Our new vlog " FP Talk with Tim " will focus on technical information, answering your industry questions and hopefully letting you see some of our company's unique cultural values.
More information about each product can be found here. The chemical constituents in Halon gases, and the products of the reactions they induce when discharged on fires, have been identified as causing damage to the Ozone layer. As a result, their manufacture and use have been banned for many years in most countries and non-essential uses have been eliminated.
However, the search for alternatives of comparable effectiveness has proved difficult and success limited, so they remain in wide use on board aircraft for most applications.
Both Halon variants work by a combination of chemical and physical effects. The chemical effects, which are dominant in their overall effect, are achieved by the atoms in the gas directly inhibiting combustion in two different ways:. Temperature reduction occurs, whenever a non-reactive gas is added to a flammable gas, because the heat liberated by the reaction of oxygen molecules with a fuel source must be distributed into the overall environment.
The rate of the combustive chemical reaction decreases rapidly with reductions in temperature and, if the concentration of added inert gas is high enough, the flame chemistry fails altogether. Halon gas mixtures are not only inert but of low temperature when released from their pressurised state.
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