Flammable liquids Fires extinguishing

Dry chemical extinguishing systems-This is used primarily for flammable liquid fires since they provide a rapid flame knockdown and e.xtinguishment. 

Some bromine compounds are covered specifically under Hazardous Materials Regulations. Other compounds may usually be shipped under the classification of chemicals, not otherwise indexed by name, without special requirements unless from their nature they would fall under a category such as combustible liquid, compressed gas, corrosive liquid (or solid), disinfectant liquid (or solid), dmg, dye intermediate (liquid), fire extinguisher, flammable gas (liquid or solid), insecticide, medicine, oxidizer or oxidizing material, poisonous liquid (gas or solid), solvent, or tear gas. Specific provisions apply to each of these categories and appropriate packaging and labeling are required. 

Water is by far the most commonly used fire suppression material and one of the most effective. However, it is important that water not be used on fires involving electricity or flammable liquids. Most flammable liquids are less dense than water and will continue to burn while floating on top of the water. In these situations, the water serves only to spread the fire and will never effectively remove the heat as intended. Since water will also conduct electricity, there is the potential of electrocution should a water extinguisher be used on an electrical fire. Water extinguishers are intended to extinguish fires in which wood, plastic, or paper are the primary fuels and should not be used on electrical or flammable liquid fires. 

All polar compounds are alike in terms of being polar. Therefore, polar compounds are soluble in polar compounds. One of the main reasons polarity is discussed in terms of emergency response is because of the foam used for fighting flammable liquid fires. Two general types of foam are used to extinguish flammable liquid fires hydrocarbon foam and polar-solvent foam, which is sometimes referred to as alcohol-type foam. The reason that different types of foam are necessary for flammable liquid fires is polarity. 

Foam fire extinguishers are used to control flammable liquid fires. The foam forms an effective barrier between the flammable liquid and the oxygen needed for combustion. Foam extinguishers are effective on class A and B fires. 

Foam extinguishing systems have been used extensively for many years, especially in the petrochemical industry, for the extinguishment of flammable liquid fires. The principal kinds of foam are chemical and mechanical (determined by how they are generated), though chemical foams are generally considered obsolete. These classes are further subdivided. NFPA standards that address this subject include the following ... 

Because carbon dioxide does little or no damage to equipment or materials with which it comes in contact, it is very useful for protection of rooms with contents of high value and contents subject to water damage. Typical of such occupancies are rooms housing hve electric equipment. Carbon dioxide is also widely used for extinguishing flammable liquid fires. 

The decision to allow the fire to consume all fuel present will be influenced by three factors. First is "What category of liquid is involved A flammable liquid, if extinguished, will present the likelihood of a hazardous vapor condition developing. Vapor clouds can be more difficult to control than a fire. The second factor to consider is the surrounding area. Will tlie plume of thick, black smoke interfere with the safety of the community Are schools or a hospital downwind that might need evacuation The third point to consider would be the... 

Unless this concentration of gas is maintained for an extended period, CO2 does not normally extinguish fires in materials that smolder or produce glowing embers, such as paper and wood. Its greatest effectiveness is on flammable liquid fires that do not involve material that might reignite after the CO2 has dissipated. It is especially suitable for use in laboratories and in the protection of electrical and electronic equipment. 

Know and understand the fire-fighting requirements should a fire occur. Dry- chemical extinguishers are best for a flammable-liquid fire. Carbon dioxide extinguishers can also be used. 

The penetration and eooling aetion of water is required with Class A fires, e.g. those involving paper, wood, textiles, refuse. Water is applied in the form of a jet or spray foam or multi-purpose powder extinguishers are alternatives. Extinguishment of a Class B fire ean be aehieved by the smothering aetion of dry ehemieal, earbon dioxide or foam. Most flammable liquids will float on water (refer to Table 6.1 under Speeifie gravity ), so that water as a jet is unsuitable a mist may, however, be effeetive. Water is also widely used to proteet equipment exposed to heat. Dry powders are effeetive on flammable liquid or eleetrieal fires. 

Foam is a proportioned mixture of water and foam eoneentrate aspirated with air to eause expansion, e.g. from 6 to 10 times the volume (low expansion foam) up to >100 times (high expansion foam). It transports water to the surfaee of flammable liquids and enables it to float and extinguish the fire. An effeetive system depends upon ... 

Dry powders are effeetive on flammable liquid or eleetrieal fires. Speeial powders are available for use on metals. Dry powder extinguishers may be used on Class C fires, ineluding gases and liquefied gases in the form of a liquid spillage or a liquid or gas leak. This must be aeeompanied by other aetions, e.g. stopping the leak this is neeessary to avoid aeeumulation of an unburned flammable gas-air mixture whieh eould subsequently result in an explosion. Aetivation may be automatie by a deteetion system, or manual. 

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