Beyond the Rule of Thumb
Survival Tip 38
By Steven De Lisi
The 2008 Emergency Response Guidebook (ERG 2008) contains 62 guides that provide safety recommendations for first responders confronting a hazardous materials incident. An orange border identifies each guide, which includes a section on emergency response actions. Listed in a bulleted format, these brief statements include steps to take when dealing with fires, spills, or leaks. Although these statements allow first responders to select appropriate strategies and tactics to achieve a positive outcome–including having all first responders return home safely–this edition of Hazardous Material Survival Tips uses real-world experiences to explain some of these recommendations.
Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. An increase in the sound from venting safety devices indicates that the tank’s internal pressure is increasing, most often as a result of flame impingement. This same flame impingement can cause the tank to discolor, which may indicate that the tank metal is weakening. First responders must remember that there is a limit to the amount of internal pressure that an operating safety device can relieve, and if internal pressure continues to build while the tank wall continues to weaken, a catastrophic tank failure is a real possibility. Never forget that even though a relief valve is operating, containers exposed to fire can still explode!
Do not extinguish a leaking gas fire unless leak can be stopped. Many firefighters are naturally inclined to extinguish any fire they confront. However, when flammable gas leak is feeding the fire, extinguishing the fire will then allow the gas to spread uncontrolled until it finds another ignition source. At that point, the fire will reignite, except that now all areas that the gas cloud covers will likely be involved in a large fireball. For flammable gases that are lighter than air (e.g., methane or acetylene), the uncontrolled gas will rise into the atmosphere; if there are nearby structures with openings such as windows or soffit vents, the gas can enter these areas and possibly find an ignition source, resulting in an explosion of the structure. For gas-fed fires, it is usually better to allow the fire to continue to burn while protecting nearby exposures. Remember that the best way to protect exposures is to apply water directly onto the exposure.
Fight fire from maximum distance or use unstaffed hose holders or monitor nozzles. In such situations, using automatic fog nozzles set on straight stream may be more effective than using smooth bore nozzles. Consider that a smooth bore nozzle’s effective reach and flow are a function of the nozzle diameter; larger flows associated with increased diameters typically require multiple hoselines to supply a master stream device. However, when setting up master streams, it may take some time to adequately supply these lines to provide the required flow for a particular tip size, especially if using a water shuttle or relay operation. For example, operations may begin using a 1¼-inch tip flowing 400 gallons per minute (gpm). However, if additional water then becomes available that enables a flow of 1,000 gpm (e.g., through an increase in the number of water shuttle tankers) the master stream device would then need to be shut down so the tip can be exchanged for one with a larger diameter (two inch). Unfortunately, the personnel responsible for replacing the nozzle tip are now exposed to a significant risk, especially if the stream is cooling a compressed tank with the potential to explode from an impinging fire. Furthermore, once larger flows are in place, one or more supply lines could be damaged (burst, run over, etc.); the suddenly reduced flow rate may compromise the stream’s effectiveness and reach. In these situations, using an automatic master stream nozzle allows for internal adjustments to compensate continuously for the amount of water supplied to the nozzle so that personnel are able to maintain a constant nozzle pressure and a more consistent pattern and reach. Remember, however, that a fire stream with what appears to be an effective pattern may still have a gpm flow inadequate to achieve the desired results.
Flush area with flooding quantities of water. This recommendation is usually for small spills of products that include certain types of oxidizers. One of the best ways to accomplish this safely is to open the large discharge outlet of nearby fire hydrants if they are available. However, before flowing water, it is usually best to determine the likely path the runoff water will take and contact local and state environmental agency representatives for their concurrence regarding your intentions. For situations in which runoff water will enter storm drains feeding into sewage treatment facilities, you must notify these facilities. Also, remember that the volume of water produced when one or more hydrants are allowed to flow uncontrolled may overwhelm the capacity of the area’s storm water runoff system.
Cover a spill with plastic sheet to prevent spreading. If the spill can be approached safely, a minimum of four first responders, each wearing full protective clothing and SCBA, should approach the spill area while each member holds one of the four corners of the sheet or tarp in one hand and a road cone or similar object in the other hand. They should approach the spill site from the upwind direction (i.e., the wind is at the first responders’ backs), and while they are straddling the spill area, the members should gently lower the sheet or tarp onto the spilled material and place a road cone on each corner of the cover to secure it in place. Depending on the spill’s size and wind conditions, you may need to use additional road cones or other objects to hold the cover in place.
Eliminate all ignition sources. Although this sounds like common sense for first responders at with incidents involving flammable vapors and gases, remember that if you request law enforcement block or divert traffic during the event, police officers may use road flares unless you specifically direct them to do otherwise. Although you should always have police officers operate far enough away from areas where there are flammability hazards, using road flares during incidents involving products capable of producing flammable gases and vapors still presents an unreasonable risk.
Another potential ignition source during hazmat incidents is any type of smoking material. However, first responders who observe anyone nearby with lit smoking materials should avoid simply telling the individual to extinguish the device and instead approach the person and escort him away from the scene. Why? If you tell someone to put out a cigarette, he will usually instinctively throw it to the ground; exactly what you don’t want him to do. Remember, that’s where the flammable gases and vapors might be!
Water spray may reduce vapor but may not prevent ignition in closed spaces. Fog nozzles can move tremendous amounts of air, which contains oxygen. Although the flammable vapor’s concentration may be too “rich” to burn (i.e., the concentration is above the material’s upper explosive limit), using a fog nozzle to reduce these vapors may simultaneously add sufficient oxygen, which can then allow the vapors to reach their flammable range. If an ignition source is nearby, this will result in an explosion.
A related hazard of flammable gases and vapors includes using mechanical ventilation to ventilate a closed space. In situations in which the concentration is above the upper explosive limit, an ignition source could be present but still be incapable of igniting the material. Although the goal of ventilation is to reduce the flammable gas’s or vapor’s concentration to zero by replacing it with clean air, this is a gradual process in which the dangerous concentrations are diluted over time. First responders should be concerned that, at some point on its way to a zero concentration, the flammable gas or vapor will pass through its flammable range. If this happens when an ignition source is present, even for just a few seconds, an explosion can occur.
All equipment used when handling the product must be grounded. During various activities that may generate static electricity, such as product transfers, grounding reduces the likelihood of spark production. Most often, a product transfer is used to move hazardous materials such as liquids and gases through hoses from a damaged container to an undamaged one. First responders should remember that any effort to ground equipment requires appropriate equipment and extensive training. The goal of establishing proper grounding is to reduce resistance to electrical flow in all equipment, including ground cables and connections. Grounding equipment must therefore be thoroughly inspected and tested before each use. Also, ground cables are usually attached to copper rods that are each several feet long and that are driven into the ground nearby, thereby developing a ground field. However, take care to ensure that these ground rods do not damage any underground utilities such as electric, communication, or natural gas lines. Preventing damage to these buried utilities requires first responders to contact the various utility locating services in their area and request that the utilities be marked. Remember, most locating services, when notified of an emergency, will respond immediately to the scene instead of having first responders wait during the 48-hour response time typically required for construction contractors.
For large fires, use alcohol-resistant foam. The ERG 2008 defines alcohol-resistant foam as “a foam that is resistant to ‘polar’ chemicals such as ketones and esters which may break down other types of foam.”1 Several ERG 2008 guides recommend this, yet for many departments, their foam inventories consist entirely of “regular foam” used with fires involving hydrocarbon fuels such as gasoline, kerosene, and diesel fuel. To effectively honor the recommendation to use “alcohol-resistant” foam, fire departments that do not stock this type of foam should know where they can obtain it, how much is available, and how it will be transported to an emergency scene. Regularly update contact information. If there is a nearby source, remember that not all foam is packaged in five-gallon containers; it might be delivered to the scene in 55-gallon drums or large totes with a capacity of several hundred gallons. Unless first responders have some way to handle these larger containers, the foam will likely remain on the delivery truck and be of little use. Remember also to check on payment for the foam. Some sources, such as fire equipment vendors, will gladly send you anything you need; they just want to know who is going to pay for it. Have a credit card or purchase order number handy just in case.
The ERG 2008 offers first responders valuable emergency response information, but it is critically important to use the correct guide. When using the blue-bordered pages that list chemical names alphabetically, remember that the under the same material name, there may benumerous variations. Some variations are based on the material’s concentration. For example, listings for aqueous solutions of hydrogen peroxide include one for concentrations with more than 60-percent hydrogen peroxide, one for concentrations of at least than 8 percent but less than 20 percent, and another for concentrations of at least 20 percent but not more than 60 percent. These three products require the using two different guides. Don’t be caught dead using the wrong one.
Another example involves “organic peroxide type D, liquid” and “organic peroxide type D, liquid, temperature controlled.” Each requires use of a different guide and, for incidents involving the temperature-controlled product, the emergency response actions state: “Beware of possible container explosion.” First responders who inadvertently use the guide for the product that is not temperature-controlled will likely miss this important warning. The difference could prove fatal.
In addition to the ERG 2008, consider other valuable information sources to during a hazmat incident such as representatives from companies that manufacture, ship, or use a particular product. Look for contact information in shipping papers and from container markings. Despite what you can learn from reading material safety data sheets (MSDSs) or other reference sources, talking to someone who handles a product every day can provide first responders’ lots of important “dos and don’ts,” many of which could save your life.
Questions or comments on this or any other monthly Hazardous Materials Survival Tip can be directed to Steven De Lisi at HazMatSurvivalTip@comcast.net.
Endnotes
1 U.S. Department of Transportation. 2008 Emergency Response Guidebook, p. 356.
Click here for more info on Steven De Lisi’s book, Hazardous Materials Incidents: Surviving the Initial Response.
Steven M. De Lisi is employed by Tetra Tech EM Inc. as a program manager responsible for planning, training, and exercise activities related to hazardous materials response. He recently retired from the fire service following a 27-year career that included serving as the deputy chief for the Virginia Air Guard Fire Rescue and a division chief for the Virginia Department of Fire Programs (VDFP). De Lisi is a hazardous materials specialist and as an adjunct instructor for VDFP, he continues to conduct hazardous materials Awareness and Operations-level training for fire suppression and EMS personnel. De Lisi began his career in hazardous materials response in 1982 as a member of the hazmat team with the Newport News (VA) Fire Department. Since then he has also served as a hazardous materials officer for the Virginia Department of Emergency Management; in that capacity, he provided on-scene assistance to first responders dealing with hazardous materials incidents in a region that included more than 20 local jurisdictions. De Lisi holds a master’s degree in public safety leadership and is the author of the textbook entitled Hazardous Material Incidents: Surviving the Initial Response, published by PennWell.
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Subjects: Emergency Response Guidebook recommendations
