SOME NEW, SOME OLD TECHNIQUES for Hazardous Materials Responders


From damage control to MacGyver-Hazmat tricks of the trade

CarolinaFireJournal - By Glenn Clapp
By Glenn Clapp CHMM, CFPS
07/05/2011 -
Although the discipline of responding to hazardous materials incidents can be viewed as a relatively new venture in the grand scheme of things, due to the fact that in many jurisdictions the formation of technician-level hazmat teams gained headway in the 1980s, we can actually trace our hazmat roots back to U.S. Navy damage control techniques from World War II and even before. As hazmat technicians, we should never forget the “tricks of the trade” learned by ourselves and others to enable us to work smarter, not harder. In this article, we will discuss some of these techniques, some of which are relatively ancient and some of which are of a more recent nature. image

Let’s begin our journey with hazmat research. When we are trying to identify the product or products we are dealing with, some simple shortcuts can serve as clues to lead us in the right direction, or at least narrow down our choices. If we notice a numerical designator with sets of numerals separated by dashes (e.g. 7664-93-9), we are likely (not certainly, but likely) looking at a Chemical Abstract Service (CAS) number. A CAS number can be thought of as the “social security number” of a chemical that can aid in the identification of a product. If we can discern a three-letter designator (such as SFA), we probably are viewing a Chemical Hazard Response Information System (CHRIS) code, found in the U.S. Coast Guard CHRIS Manual. As we can recall from our operations-level training, a four-digit numerical code (1830, for instance) may signify a UN/NA ID number, found in the Emergency Response Guidebook. Finally, if we are viewing a seven-digit numerical code with no spaces or dashes (e.g. 4930040); we might be encountering a Standard Transportation Commodity Code (STCC), which is oftentimes utilized in railroad transportation settings. The next generation of STCC is the five-digit Standard Classification of Transported Goods (SCTG) code, which is designed to be used in non-railroad settings and in concert with the internationally-utilized Harmonized System (HS).

Next, we will take a detour down the road of air monitoring. Let’s say that you are making entry into an area in which a product that displaces oxygen is present and you need to determine the concentration of the product and have no other options for quantitatively measuring the concentration of the substance. If you have an oxygen sensor, a very close approximation of the concentration can be determined. We should remember from hazmat technician class that the normal concentration of oxygen in air is 20.9 percent, or roughly one-fifth of the atmosphere. If a product lowers the oxygen concentration from 20.9 percent to 20.4 percent, we can say that a 0.5 percent oxygen displacement has occurred. We can then utilize the conversion factor of 1% = 10,000 ppm to convert our percentage displacement to parts per million (5,000 ppm in this case) and then multiply the result by five since oxygen makes up one-fifth of the atmosphere to arrive at the concentration of our product, which in this example is 25,000 ppm.

Since most readers are most likely developing a headache at this time and are thinking “Enough of the academic side of things, let’s talk about the fun ‘hands-on’ topics,” we will do just that. In the area of product control, there are some everyday items that are often indispensible on hazmat incident scenes. One such “high tech” item is a golf tee. If you have a liquid leak from a small hole in a container or from a small line or pipe that cannot be crimped or otherwise controlled, a simple golf tee can be inserted to stop the leak and will work when nothing else will. Another item that can sometimes be “worth its weight in gold” is a wax toilet seal (I know, I can hear the collective laughing already). Although there are many fine products available to curtail hydrocarbon leaks from fuel tanks, wax toilet seal gaskets are very inexpensive and work exceedingly well in such a situation by simply pulling off a sufficient amount of the wax seal, balling it up, and placing it over the leak.

Other items that are handy to have in your product control tool bag include small-diameter rope and patches made of a material compatible with the product you are working with. Liquid leaks in piping often occur at pipe junctions, bends, and other locations where conventional pipe sleeves simply will not work.

An old U.S. Navy damage control technique may pay off in this situation, as a suitable patch can be applied over the leak and the small-diameter rope lashed over the patch to stop the leak. The aforementioned technique may be old-school, but it usually works when no other technique will.

A melding of such an old-school technique with modern equipment was once utilized in a railcar specialist class, in which a leak from a general service railcar was controlled using a magnetic patch, a raincoat, and the lid from a five-gallon bucket. I am not necessarily advocating that arrangement, however it worked and I will leave it up to your imagination to form a mental picture of that control technique.

An additional item that can prove useful in a railcar incident in which the frangible disc of a pressure relief vent on a general service railcar has ruptured and the liquid product is sloshing out of the open vent while there is not an excess buildup of pressure is a tennis ball. In such a case as described, the vent cover may possibly be removed, the tennis ball inserted over the ruptured disc, and the vent cover tightened to secure the tennis ball in place to contain the product if the pressure in the rail car is monitored closely. One thing to look out for, however, is the citizens of your jurisdiction viewing the tennis balls stored on your hazmat unit at equipment displays and wondering what the heck the tennis balls are there for.

Two additional control techniques that do merit discussion when dealing with gases are the autorefrigeration method and the tarp and cover method. As we know that Charles’s Law states that pressure is proportional to temperature (or as the temperature of a gas increases, so does its pressure and vice-versa), the autorefrigeration method can sometimes be utilized in controlling leaks of products such as liquefied petroleum (LP) gas. If other control measures have failed, a wet towel or rag can be placed around the leak and Charles’s Law can be used to our advantage. As the pressure of the product exiting the container drastically lowers at the point of exit into the atmosphere, so does the temperature. The lowering of the temperature can actually freeze the wet towel or rag, temporarily stopping the leak (picture your SCBA cylinder valve frosting over when you are breathing heavily from your SCBA).

The tarp and cover technique is sometimes used to reduce the impact of anhydrous ammonia leaks occurring in an outside environment. To perform the tarp and cover, a tarp is placed over the point of release of the anhydrous ammonia and weighted down at ground level to cover the area of release. This action condenses the dense gas emanating from the point of release into the liquid phase, which then cools the release point and decreases the associated pressure of the product, thereby slowing the release and hopefully decreasing the geographic area impacted by the release of product. The ammonia that condenses under the tarp will cool to form liquid ammonia that will pool on the ground.

An area that has not been touched in our discussion of tricks of the trade is that of personal protective equipment (PPE). When making entry in fully-encapsulating vapor protective chemical protective clothing, we are all aware of the limitations imposed on our dexterity and range of movement. It we drop a small item such as a nut or washer, it can be nearly impossible to pick it up while wearing three pairs of gloves. To prepare in advance for such an occurrence, we can loosely place a small ball of chem tape on the sleeve of our hazmat suit to enable us to easily pull off the ball of chem tape and use it to pick up any small items that are dropped. The chem tape may also come in handy if a small hole or tear develops in our or our fellow Entry Group Member’s chemical protective clothing, in which case the chem tape can be applied over the hole or tear. Chem tape can also be utilized to visually designate individual Entry Group Members by placing a piece of chem tape on the suit of one Entry Group Member and not the other.

The final trick of the trade that we will discuss is in the area of the grounding of containment vessels. While we have utilized grounding rods for many years to equalize the electrical potential between the ground and our containment vessel, a favorable alternative that is inexpensive and very effective is the use of aluminum foil (yes, the same aluminum foil we buy at the grocery store). Instead of driving a grounding rod into the ground, try digging a shallow trench in the ground, unrolling a length of aluminum foil as long as is practical and covering the foil with dirt. The ground wire can then be connected to the foil to achieve the proper ground. Water and even rock salt can be added in the trench with the aluminum foil prior to the trench being covered to enhance the ground.

Why does such a grounding setup work well? Think of the surface area of the flat length of the foil compared to that of the cylindrical grounding rod that contacts the earth (the more surface area, the better the ground). The aluminum foil technique even works well in sandy-type soils.

In conclusion, it is hoped that one or more of the hazmat tricks of the trade discussed above may prove useful during your hazmat career. The use of such methods should only be attempted in applicable situations utilizing properly trained personnel and with safety foremost in mind. While some of the techniques discussed above may sound like they come from an old war movie or an episode of the TV show “MacGyver,” they actually do work in the proper situations and can be an important weapon in our hazmat arsenal. As always, be safe out there and be sure to visit the North Carolina Association of Hazardous Materials Responders’ Web site at www.nchazmat.com.

Glenn Clapp is President of the North Carolina Association of Hazardous Materials Responders and is a Fire Training Commander (Special Operations) for the High Point Fire Department. He is a Technician-Level Hazmat Instructor, a Law Enforcement Hazmat Instructor, and is a Certified Hazardous Materials Manager and Certified Fire Protection Specialist.
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