54 SPRING • 2011
HAZMAT
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Carolina Fire Rescue EMS Journal
The ‘Big Five’ A Systematic Approach to Evaluating Product Hazards By Glenn Clapp CHMM, CFPS
Back in the 1980s, a concept emerged in the aviation world known as “Crew Resource Management” (CRM), which broadly applied to the study of human behavior in aviation — e.g. how flight crews react to and handle in-flight situations — and specifically related to a “Unified Command” type concept in managing flight operations through joint input of crew members. An additional component of this concept was the development of a “flow” in each crew member’s actions in each type of specific situation or operation — performing task A before task B, etc.This same idea of developing an operational “flow” is also evident in fire service operations, such as pumping operations on the fire
scene.The prudent apparatus operator, or aspiring apparatus operator, will develop a distinctive “flow” in his or her actions, as is summarized by some sources in the Seven Steps of Pump Operation. The concept of developing a “flow” in your fire service operations can also be applied to the hazmat arena. If I am dispatched to a hazmat call, I like to apply the “flow” concept to the hazards that may be presented by the products involved. Specifically, I like to consider the following five factors: Radioactivity – Will the product present a radiological hazard? This was discussed in the previous issue’s article on radiological monitoring. Corrosiveness – Will the prod-
uct eat away metal or skin? Flammability – Will the product ignite or explode — in nontechnical terms, is it going to go “whoosh” or “boom”? Vapor Production – How quickly will the product evaporate? Or, what is the level of vapor production? Toxicity – Will the product present a hazard to our health?
Radioactivity As the factor of radioactivity was previously discussed, let us first take a look at the concept of corrosiveness, which we evaluate using the measure of pH.The pH of a substance delineates its relative corrosiveness and whether the substance is an acid or a base (bases are also known as alkalines
or caustics).The pH scale runs from zero to 14, with neutral being seven. Substances with a pH less than seven are classified as acids, whereas substances with a pH greater than seven are said to be basic in nature. Specifically defined, pH is the negative logarithm of the concentration of hydronium ions (H3O+) in a solution (a low pH indicates a high hydronium ion concentration and vice-versa).
Corrosiveness You may then be tempted to ask,“why are we concerned with corrosiveness?”The answer is two-fold, in that an acidic or basic product may degrade our personal protective equipment — inclusive of our suits, boots, gloves, and respiratory protection if the respiratory protection is externally worn. And, it may also negatively impact the operation of our air monitoring sensors, thereby rendering our air monitoring activities employed as part of a risk-based response approach null and void. Or, as I sometimes say, turning your meter into a wheel chock. Although we may utilize a pH meter to determine corrosiveness in the field, the tried-and-true method that we normally use is the low-tech approach of pH paper.The pH paper can be taped to our PPE, can be mounted to a stick or pike pole to give us a forewarning of a corrosive environment, and can be wetted with
distilled water to allow a more rapid detection of a corrosive vapor. Acids or bases will be displayed on the pH paper as distinctive color changes.
Flammability The third factor of the “big five” is that of flammability. One way in which flammability can be categorized is by flash point. As we recall from fire behavior class, flash point is the minimum temperature at which a liquid produces a sufficient quantity of vapor to form an ignitable mixture that will flash if an ignition source is present and then may go out.The lower the flash point, the more hazardous in terms of flammability the substance is. Flammability may also be categorized by ignition temperature, which is the minimum temperature at which a substance will ignite and continuously burn. It can also be thought of as how hot the ignition source needs to be to produce continuous combustion. Flash point and ignition temperature oftentimes can be viewed as a “see-saw” type of arrangement. For example, gasoline has a relatively low flash point of -45o F and a relatively high ignition temperature of approximately 700 o F, whereas diesel fuel has a relatively high flash point of 124 o F and a relatively low ignition temperature of 494 o F. An additional concept in flammability is that of flammable range.The flammable range