Distinguishing Danger: Up Close and Personal with a Polymerizer

BY NIK KIMBEL

FOR YEARS, hazmat instructors and course content have stressed the importance of recognizing a few critical elements that can present serious problems. These include the following:

Explosive atmospheres.
Radiation.
Presence of fluorine.
Corrosive atmospheres.
Rapidly rising temperatures.

As history has shown, what we haven’t seen before can kill us. This tragic reality is true for routine calls, but it’s especially important to be on alert when you get specialized calls that you run far less frequently.

One Department’s Experience

On a warm summer night, a neighboring fire district responded with two engines to a general fire alarm at a chemical plant that specializes in coatings and composite products. Both the hazmat team and the local fire district were familiar with the plant due to previous responses over the years. While the call didn’t appear to be significant, it was definitely out of the ordinary.

On arrival of the first unit, responders found a foam system flow alarm in the loading dock area on the grounds that housed almost five acres of numerous multistory tanks, buildings, and transport containers.

One of the members of that night’s on-duty skeleton crew reported a loud boom in the loading dock area, which may have involved one of the on-site chemicals. Recognizing its potential to be a hazmat incident, the crew notified the fire district duty officer. On arrival of the duty officer, the crew transmitted a hazmat first alarm. This also notified the hazmat duty officer. A full hazmat major response went in motion.

St. Louis County (MO) Hazmat is a regional response team equipped to handle all response types. Incidents they can handle include the following:

Chemical.
Biological.
Nuclear.
Radiological.

During a major hazmat response, the main response vehicle is staffed with three to four technicians. Several technicians also staff a decontamination vehicle from one of two regional agencies from the north or south. In addition, on-scene agencies and personnel callouts supply several more technicians.

Once the team assembled on site, we entered the building in question, assessed the situation, and determined the developing and existing hazards. Since most of the chemicals on site were toxic and flammable, structural turnout gear with a self-contained breathing apparatus was the most appropriate.

When we entered the loading dock, approximately 100 feet away from the pedestrian door, the only significant reading-less than 50 parts per million (ppm)-was a signature on the photoionization detector (PID). A PID identifies the presence and amount of organic vapors and gases in the air. While it is able to detect many different compounds, with an indication of the amount in ppm, it will not fully identify or detect all chemicals. It is still useful during attempts to find the source or area of concern. During our search with the five-gas monitor, no other readings were noted on oxygen, carbon monoxide, lower explosive limit (LEL), or hydrogen sulfide. The standard paper indicators located in front of us in the entry basket also did not react. This included pH, water paper, oxidizer paper, and fluorine paper.

Situational Awareness

As we made our way to the loading dock, taking high-, medium-, and low-height air readings along the way, we noticed that the floor was covered in fire suppression foam solution and a popcorn-like substance reminiscent of a cereal from my childhood. The appearance confused me for a moment, since there was no sign of heat, fire, or anything I would normally associate with a chemical. As we worked our way closer to the source of the problem, I noticed that water was flowing from a pipe on the ceiling. However, I zeroed in on the barrels in the area and popcorn-like substance on the floor, lacking some situational awareness.

At about the same time I started examining the barrels that might have been the problem, my partner tapped me on the shoulder and told me to look up. One of the barrels containing the polymerizer had exploded. This blew out the bottom of the barrel, shot straight up about 12 to 14 feet, and wrapped itself around a fire sprinkler supply pipe, breaking the foam system pipe in the process (photos 1 & 2).

foam system pipe — 1. Photos by Josh Kaiser unless otherwise noted.

The explosion was the primary cause of the flowing water and foam mixture. Fortunately, it seemed that the foam solution had likely helped cool down some of the barrels and prevented ignition. I was shocked that I had missed that big, obvious clue. So now it serves as a lesson on the importance of operating in teams: to help each other retain some situational awareness.

As we pieced this puzzle together, we noticed dozens of barrels of the same product had palletized, just inches from the exploded barrel. Knowing that the only indication of a runaway reaction was a temperature reading with a temperature gun and a thermal imaging camera (TIC), we carefully took the temperature of surrounding barrels on the top, middle, and bottom of each one until we identified any additional hazards. Thankfully, none of them revealed signs of thermal runaway. After exiting the building and going through the decontamination corridor, we briefed our findings to the hazmat group supervisor (photo 3). He told the facility worker who—suddenly recollecting-responded by saying, “We have a refrigerated room for some of those chemicals. I bet those go in there.” Everyone within a mile radius of that place at the time was, collectively, annoyed.

While we debriefed, we researched the product inside the barrels in question: “styrene monomer.” One piece of information that I recognized from the DOT Guide Number and the National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards was “P” and “Polymerizer.” Without having seen an example of runaway polymerization or its aftermath in real life, I lacked the knowledge to grasp that the popcorn-like substance was an identifier for what we were dealing with (photo 4).

Identifying Polymerizers

In addition to their flammability, polymerizers can create a deadly situation of container overpressure for firefighters. There are very few obvious exterior signs of a runaway reaction happening in a container, and our only defense is through the use of a thermometer or TIC. However, to use it correctly, we must know the thermal measuring device’s limitations: the distance to spot ratio for a temperature gun or the concept of emissivity for TICs (in addition to many other factors).

It is also crucial for anyone using these devices to understand their nuances: operating conditions, temperature readouts, sensitivity modes, and more. In similar fashion to a pipe bomb, once pressure builds up and bursts the pipe, the rapid release of pressure and energy can cause injury and death. In industrial-sized containers of polymerizer, the intense pressure built by a material akin to insulating spray foam and the pipe bomb could be the size and shape of a 55-gallon drum or a 31,000- gallon railcar.

runaway polymerization — 4. Photo by Mike Siegel.

Once you enter the room containing the tank or vessel, assess the tank for any obvious problems or damage, then take a temperature with the thermal measurement device. A reading of the first number should be noted and relayed to command. This will avoid task saturation and misunderstanding. After the completion of a quick 360° assessment of the tank, take another measurement of the same container in the same spot to determine if the temperature has risen significantly. (A significant rise is defined as more than a few degrees higher without external factors causing the increase.)

Make sure the measurement reflects the temperature of the actual tank metal and not a thermal jacket that is an insulating outer layer. If a thermal runaway is happening, the temperature will rise. Most of us who have had hazmat operations-level training have a decent grasp on the dangers of a polymerizer. Even so, nothing in my experience could prepare me for what a breached container would look like or exactly what kinds of forces we were dealing with.

Only after I ran the call did I find a rare example in a video from the 1970s in which a runaway reaction was happening in a railcar at a chemical facility. Once responders recognized what was going on, they isolated the railcar to a remote line and attempted to cool it down with unmanned master streams. After some time, it still exploded and spread the foamy popcorn-like substance over hundreds of feet.

Runaway Reactions

Identifying a polymerizer and its reaction in the container with the temperature measurement device is the most important step, but there is little one can do for runaway reactions. Some clues that identify a polymerizer are DOT Guides with “P” on the end (seen in styrene monomer and Guide 128P) or words such as “polymerize” or “polymerizer” in the “Incompatibilities and Reactivities” section of the NIOSH Pocket Guide.

Once those pieces are identified, the best plan is to evacuate the area and put some distance between individuals and the container. These chemical products have inhibitors, which keep the chemical from reacting when it’s stored at the proper temperature. But once heat increases, like during an impinging fire, or the product gets out of its required storage temperature range, the runaway reaction begins, as was the case for our call.

The barrels of styrene monomer were supposed to be stored in a cooled room off to the side of the loading dock door, to maintain a product temperature of less than 70°F. Instead, they were stored in a non-climate-controlled area, subject to ambient temperatures, which can reach upward of 90°F. In some cases, during an impinging fire or in a smaller container, we can attempt to cool with unmanned hose streams, but this tactic should always be performed at a safe distance. Success may be limited, since this reaction happens inside the tank at a molecular level.

Knowing the Consequences

Polymerizers are unlikely to be seen very often but can have serious consequences if there is failure to identify and assess the situation. The primary hazards of these products are flammability and runaway polymerization. We can identify the flammability component with our LEL sensors and PID. And we can identify the possibility of polymerization with a temperature measurement device. However, it is critical to learn the proper use of the instruments and their limitations to get the most accurate information.

This chemical facility and community were very lucky. If the barrel of polymerizer had traveled a few feet in a different direction, it would have struck one of a dozen 10,000-gallon tanks of flammables nearby, resulting in a chemical liquid fire that would have required additional resources and would have significantly increased the risk to everyone’s safety.

Knowledge Is Power

This experience resulted in several lessons and takeaways for my department, and I hope they can be helpful to yours. Know your equipment. Know the ideal distance to spot ratio for temperature guns and TICs, the concepts of emissivity, temperature readouts, and sensitivity modes and settings for our TIC to get the most accurate information. Bring protective tools like monitors and identifying papers to identify LEL, radioactivity, pH, and fluorine and a temperature gun or a TIC. And make sure to wear full personal protective equipment.

Know how to spot the evidence of a polymerizer by following DOT guides with a “P” at the end, as seen in “Guide 128P,”¹ or learning terms such as “may polymerize” or “polymerizer” from research sources like the NIOSH Pocket Guide.² Be sure to read the manual. Take every potential hazmat alarm seriously. We cannot get caught with our guard down.

ENDNOTES

“Emergency Response Guide No. 128P for Flammable Liquids (Water-Immiscible).” Emergency Response Gudiebook (ERG), U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration, bit.ly/47ZepnK.
National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards. NIOSH, 2020, bit.ly/4eWlTu4.

NIK KIMBEL is a 21-year veteran of the fire service and a firefighter/ medic with the Creve Coeur (MO) Fire Protection District. He is also a 14-year member of Missouri Task Force One (FEMA USAR) and a rescue specialist. Kimbel is a member of the St. Louis County Hazmat Team and is an instructor and consultant for the hazmat team and private industry. Kimbel is a Certified Hazardous Materials Manager (CHMM®) and has master’s degrees in occupational safety management and industrial hygiene. He is also a cocreator of the Make Hazmat Great Again podcast on Youtube.