CNG truck fire presentation: To the brotherhood of firefighters

Former firefighter Larry Stone, now the director of emergency services for 1-800-Board-Up in central Florida, has been giving this presentation on CNG trucks around the central Florida area


By Larry Stone

My name is Larry Stone; I am a former firefighter from the Cincinnati, Ohio area. I started my fire service career in 1972 at the Crosby Township Fire Department, Hamilton County Ohio. In 1975, I joined the Colerain Township Fire Department during a time when our entire township was merged into one department. The Groesbeck Fire Department and Colerain Township Fire Department became one department.

Today, this department has a proud history and continues to be a leader in Hamilton County Ohio. Later in 2008 to 2013, I also served for several other area fire departments; Cleves Fire Department, Hanover Township Fire Department in Butler County and finally I retired from the Village of Glendale Ohio Fire Department March 2013. During my past fire service career, I have served as a senior engineer, public safety officer, first-aid trainer as well as a public information officer.

My professional career in the solid waste industry began in Cincinnati, Ohio 1972. I was the appointed the Corporate Safety Director in 1985 and continued in waste industry until 2015 in central Florida.

Fires of all types of trash trucks can be somewhat common. I categorize these into three areas; cab and chassis, brake/tire and load fires.

Poor maintenance or electrical problems is often the cause of cab and chassis fires. Debris from dumping trash can accumulate on or around the engine compartment and transmission area, which may result in a fire. These fires are intensified by saturated oily surfaces from hydraulic and engine oil.

Today's trash trucks a have live power take off unit, or PTO, which allows the driver to pack the load while moving. A small leak in the hydraulic system can cause a big problem. A small leak in a high-pressure line can create atomized hydraulic fluid. Atomized hydraulic fluid has a very low flash point; today's trucks have a regeneration process that creates 1,800 degrees at the exhaust system. Add these two elements and we see cab and chassis fires.

Numerous truck drivers through the years have overheated brakes, smoked brakes or even "lost brakes" on down-hill grades because of improperly adjusted brakes, use of improper techniques, stuck pads or brake shoes, or a combination of issues. If the brake fire is not extinguished quickly, there is a risk of the tires catching fire and eventually exploding from the fire and heat.

Load fires can be caused by various materials carried from the residential or commercial collection process. One of the most common is swimming pool chorine. Residential trash is normally 60 percent moisture. Once compacted in the load compartment, this moisture is collected in what's called the sump. As the truck moves forward, air is introduced into the load compartment and acts like a bellow. We often see spontaneous combustion or a load fire.  

These two professional careers have allowed me to see many types of emergency situations including many fires in solid waste trucks as well as major landfill and recycling center fires. What this publication is about is Compressed Natural Gas (CNG) vehicle fires. I have no problem with alternative fuel vehicles. We need to be progressive and open to new ways to develop resources. However, I have seen some things that concern me that I what to share with you. I can no longer stand by and just pray that a fire fighter is never injured in this situation.  

I want to share with you four videos that will reinforce my concerns for fire fighter safety as they approach a CNG powered vehicle fire.

The first video is from January 27, 2015, this was a refuse truck load fire near Indianapolis, Indiana. Please be sure to watch the entire 2:05 video.

Things to watch for and note:

  1. The amount of damage to a heavy-duty steel commercial refuse vehicle truck body, At the 41-second spot, I have seen fire fighters in this area during normal extinguishment efforts.
  2. The CNG cylinders are designed much like the SCBAs used in the fire service today. You will notice these cylinders are equipped with pressure release devices (PRDs) on both ends. The PRDs release with a combination of pressure or at approximately 219 degrees. Noted at the 53-second spot.
  3. Debris traveled nearly 1,000 feet and landed in a nearby school yard. Noted at the 106-second spot.
  4. A large cylinder traveled a great distance. Pay close attention to the PRDs, which seemed to be intact. One can assume, if the PRDs would have released the tank would not have exploded. Therefore, the PRDs were defective or never reached temperature. Noted at the 107-second spot.
  5. While interviewing a witness, he describes the explosion may have taken place as much as 30 minutes after the fire was first noticed and after fire fighters were on scene. Noted at the 122- to 131-second spot.
  6.  In most all cases, fire fighters may be on scene and actively engaged in fire suppression activities after that amount of time.
  7. ​In this video we cannot see any indication that the PRDs released which may have caused the explosion.

The second video is from July 2, 2015, this was a refuse truck load fire, which occurred in Chesapeake Va. Please be sure to watch the entire 2 minute and 15 second video.

  1. Notice the distance the truck is from the residence. I can only estimate the distance, but it appears to be about 35 feet. Noted at the 43-second spot.
  2. Note the volume of fire as the PRDs on both sides of the refuse truck release. Noted at the 113 to 128 second.
  3. Again note, in many cases fire fighters are actively engaged in fire extinguishment.
  4. In this video, we clearly see the PRDs release and no one was in harm’s way.

Things to watch for and note:

The third video is from April 18, 2011. This was also was a refuse truck load fire in Kokomo, Indian. Please be sure to watch the entire 15-minute video.

Things to watch for and note:

  1. First of all, it's important to note that most waste collection drivers are trained to dump their hot load in a safe place when possible.
  2. Many times the electric or hydraulic system is compromised and dumping the load is not an option.
  3. The fire can also compromise the driver's ability to move the vehicle in some cases.
  4. Because of my background in the solid waste industry, I can see this is a CNG powered vehicle.
  5. The added boxed in area on top of the truck houses the CNG tanks.
  6. Some manufactures have begun housing these tanks in the tailgate. Therefore, you may not be able to actually see that the vehicle you are approaching is powered by CNG fuel.
  7. You will also not be able to tell what type of cylinder the vehicle is equipped with. Type 1, 2, 3 or 4.
  8. Cooling the PRDs while you have active fire may create the conditions for an explosion.
  9. Clear view of CNG tank housing and active fire near the PRDs. Noted at the 54-second spot.
  10. Increase in active fire near the PRDs. Noted at the 4:10 mark.
  11. The Battalion Chief arrives and conducts a 360. Each time he passes the sides of the vehicle we now know he is in harm's way if the PRDs release. Noted at the 6:03 to 6:26 marks.
  12. The Company Officer joins the BC for a second 360; now both are clearly in harm's way. Please keep in mind, this is happening across the country today at many CNG vehicle fires. We understand that pre-incident knowledge and training is power and reduces the potential impact to firefighters.
  13. First water was applied to the fire at the 8:20 mark.
  14. It appears that the firefighter is applying water directly on the PRDs, which could increase the risk of an explosion. Noted at the 8:27 mark.
  15. A master stream with foam is now applied and about 10 seconds later we have knock down. Noted at the 10:05 to 10:15 marks.

Finally, to show just how fast the system can ignite after a PRD release, view this brief video.

I do not want to be an alarmist, but I also do not want to wait until I hear of a line-of-duty death or serious injury to a brother or sister firefighter. My goal is simply awareness. I hope that after watching these videos your department will re-evaluate their approach to CNG refuse truck fires and conduct your fire ground operations to minimize the danger element to firefighters.

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