Fire Extinguishers

In some fires, occupants of a building use a number of first-aid methods to attack the fires before the arrival of the brigade. Portable fire extinguishers constitute one such method apart from “sundry means” such as buckets of water or sand, garden hose, and smothering. Fire Extinguishers available in the market are mainly of the following types

• dry powder,
• water,
• carbon tetrachloride,
• foam, and
• other vaporizing liquids and carbon dioxide.

Some fires are extinguished or controlled by first-aid means. An initial attack by occupants does reduce the severity of a fire, but there have been some instances in which such an action has led to fatal or nonfatal casualties. In industrial and commercial buildings (Table 10.3, below), early detection followed by quick action to extinguish the fires by sprinklers, extinguishers, or “sundry” means reduces the damage but this saving would be higher if first-aid fire fighting is not undertaken. This implies that, if a fire is discovered early by human or automatic detection devices, the fire brigade should be called quickly instead of launching an attack by first-aid means.

Reference: Evaluation of  Fire Safety. D. Rasbash, et al

While early detection followed by a call to the fire brigade appears to be a better option than first-aid fire fighting, some doubts on the effectiveness of fire extinguishers have also been cast by some research studies in the United Kingdom. An analysis of fire brigade data by Ramachandran et al. (1972) disclosed that extinguishers were unlikely to be as effective as “sundry” means in attacking dwelling fires. In this study, the effectiveness of first-aid methods was assessed in terms of proportion of fires put out by these methods and the average time taken by brigades to control fires that were not put out. Occupants were able to put out 43% of the fires tackled by “sundry” means but only 27.5% of those in which extinguishers were used. The average control time of a fire brigade was 6.5min for “sundry” means and 8.9min for extinguishers. Without further statistical analysis, it was found difficult to judge the significance of this difference in mean control time.

It was possible that extinguishers in dwellings were located at considerable distances from the places of fire origin, for example, cars and garages. An analysis by Simeet al. (1981) gave some indication that people have inadequate knowledge of the location of extinguishers. A householder may be more inclined to tackle a fire in an armchair than one in a fat pan. According to Chandler (1978), people were less likely to use extinguishers on small fires, which might partly explain the lower success rate with extinguishers than with other methods in hospitals. This conclusion was confirmed by Canter (1985) who found that the contribution of extinguishers to fire fighting was subject to many constraints in actual fires. Canter also suggested that people (especially staff in hospitals, hotels, etc.) should be made aware of the location of extinguishers, and trained in the use and capabilities of different types and sizes of extinguishers.

As in the case of sprinklers, a number of small fires extinguished by portable fire extinguishers were not reported to the fire brigades. In the United Kingdom, statistics supplied by the Fire Extinguishing Trade Association (Fire Prevention, March 1990) indicate that over 70% of fires were not reported to the fire brigade because they were put out by fire extinguishers. In addition, 17% of the fires reported to the brigade were found to have already been put out by staff or residents using fire extinguishers prior to the brigade’s arrival. All the factors and data men-tioned above should be taken into account in a detailed statistical analysis for establishing the effectiveness of extinguishers.