Research Paper on Involving Fire Suppressants

Introduction

An incident involving suppressants is one which The National Institute for Occupational Safety and Health (NIOSH) had an investigation launched and finalized on July 6, 2010, after one firefighter died and eight others injured in the line of duty in response to a dumpster fire at a foundry in Wisconsin. On examination, the fire was approximately two foot high and emitting blue-green flames at the top with a red-orange glow in the heart of the fire. The firefighter's response to the suppression of the fire was 700 gallons of water with no effect and then 100 gallons of foam solution at one percent then increased to 3percent and no noticeable effect. The contents of the dumpster then exploded sending shrapnel and barrels into the air. The explosion was the cause of the one fatally injured firefighter and eight other injuries. Further analysis provided the revelation that one of the components of the dumpster fire was aluminum shavings which upon addition of wet extinguishing agents generated hydrogen gas as a result of the reaction with aluminum which exploded.

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The fire suppressants in the incident are water and foam solution. Water as a fire suppressant is generally used for Class A fires due to its very predictable components such as boiling at 100 degrees and freezing at 0 degrees compared to other fire suppressants such as nonaqueous agents which may contain unpredictable characteristics. (Gann & Friedman, 2014). It is a well identifiable fact that water slows the growth of a fire due to its ability to effectively control all components of the combustion process which are oxygen, heat, and fuel. Foam solution was the other suppressant used in the incident. Foam agents suppress the fire by separation of the fuel from the oxygen and are dependent on the solution, foam solution is mainly used for Class B fires. In the above incident, however, it is imperative to focus on one pertinent suppressant which is water.

Water is the most conventional, accessible, and convenient for use and the cheapest media for the suppression of fires of a general nature. Water is the most used component in Fire Services to put out fires in one form or the other. The characteristics of water as a fire suppression agent are essential knowledge to any firefighter and the reason why water is the best extinguishing agent when used appropriately and efficiently. Some of the characteristics are its affordable nature and readily available. Water also contains excellent cooling properties as it changes states it has the ability to absorb a high amount of heat. In the process of extinguishing a fire using water, the water heats up as heat will move from the higher temperature to the lower temperature which is the water. It, therefore, leads to water heating up and changing states to vapor or steam which then leads to the steam heating up until an equilibrium of steam and smoke is attained which leads to the suppression of the fire, therefore, portraying the excellent cooling properties of water (McDonough, 2018).

Real life experiences involving water as a suppressant include incidents where a small home fire is actively suppressed by the home sprinkler system which quickly averts the danger of the fire spreading. The National Fire Protection Association has produced reports as to the importance of automatic sprinkler systems. (Rohr et al., 2005). An article with statistical data by the NFPA provided that injuries to the firefighters were 79% lower where sprinklers were present. (Ahrens, 2017). An example would be a small fire caused by something left cooking in the kitchen, the water-based sprinklers are able to reduce the probability of the fire becoming a large fire by putting it out automatically.

In the above-stated incident, wet extinguishing agents were neither ideal nor effective in the suppression of the fire due to the components later discovered that is aluminum shavings which led to the explosion. The fire suppressant that would have been ideal for the unique incident as provided by the NFPA was that in lieu of using a wet suppressant that is water and foam, bulk dry agents can be used such as dry sand or dry sodium chloride. In contrast to water, it was stated that the availability of highly combustible aluminum shavings led to the volatile reaction producing hydrogen gas thus the explosion hence water was not an effective extinguishing agent in this case. (Ahrens, 2017). Dry sand or dry sodium chloride would have been ideal as no reaction would have occurred with the aluminum shavings hence no explosion and therefore an effective fire suppressant. In comparison, however, both water and dry bulk agents such as dry sand are both effective extinguishing agents when used appropriately to fit into the situation. It is therefore pertinent to thoroughly conduct a good size up to make sure there are combustible metals involved and how to handle the fire if there is any present.

The chemical phase of a fire suppressant such as water can be considered to have three main steps. The first step is when the water heats up as when putting out a fire using water, the heat will move from higher temperatures to lower temperatures(water), which leads to water heating up. The second step is then water turning to steam due to the high heat induced by the heat transfer. The third step is the vaporization where heat transfer continues which leads to thermal equilibrium and hence the fire is suppressed. The mechanism of action, therefore, is a description of the effects of the chemical phase of the suppressant. (Sheinson et al., 1989). To extinguish a fire continuously burning with a supply of oxygen and fuel, the fire suppressant has a cooling effect and an inerting effect. The suppressant must limit either fuel or oxygen to extinguish the fire. A water mist suppression system has both cooling and inert effects. The cooling effect will bring the conditions to lower temperatures while the inerting effects will bring the conditions to lower oxygen concentration. (Tarpley et al., 1980)

The mode of application of fire suppressants can be through cylindrical nozzles such as those in fire extinguishers, hose pipes with large nozzles as used by firefighters or automated fire control systems that can suppress a fire without any human interaction such as sprinkler systems. Application systems in the United States are governed by The National Fire Protection Association and are in use to prevent the spread of fire or extinguish a fire. There are different types of fire suppression systems such as the sprinkler systems, fire extinguishers, gaseous agents, and wet and dry suppression systems.

References

Ahrens, M. (2017). Trends and Patterns of US Fire Loss. National Fire Protection Association (NFPA) report.

Gann, R., & Friedman, R. (2014). Principles of Fire Behavior and Combustion. Jones & Bartlett Publishers.

Mcdonough, J. (2018). The Science of Water Extinguishment. Retrieved from www.firehouse.com

Rohr, K. D., & Hall, J. R. (2005). US Experience With Sprinklers and Other Fire Extinguishing Equipment. Quincy, MA: National Fire Protection Association.

Sheinson, R. S., Penner-Hahn, J. E., & Indritz, D. (1989). The Physical and Chemical Action of Fire Suppressants. Fire Safety Journal, 15(6), 437-450.

Tarpley Jr, W. B., Huzinec, J. R., & Freeman, M. K. (1980). U.S. Patent No. 4,226,727. Washington, DC: U.S. Patent and Trademark Office.