How Well Do You Know Your Meters? Part 1

By Kevin Yoos

Over the past few decades, the fire department mission has evolved so that firefighters are the “Do It All” responders. We all know the runs I’m talking about: EMS, water leaks, water rescue, wires down, stuck elevators, strange odors, gas leaks, and of course the carbon monoxide alarm. It’s not just about responding to fires anymore. Firefighters need to be proficient in many different areas and we need to be at the top of our game on every alarm. Let’s concentrate on one area–meters for the first responding firefighters.

In most areas, laws went into effect requiring carbon monoxide meters to be installed in residential and commercial structures. Of course, these laws affected the local fire departments that respond to these alarms once they activate, and, as we all know, when the low battery chirps. Fire departments across the country immediately had to purchase metering devices and train their firefighters about carbon monoxide (CO). Firefighters began learning how these meters work, but how well do you know your meter? Is it telling you all the information that you need?  Some departments choose to purchase a multigas (four- or five-gas) meter. These will most likely read oxygen, carbon monoxide, hydrogen sulfide, and lower explosive limit. Other departments have chosen to purchase a single-gas meter that just reads CO. So what is the best option for your department? Are the current meters and knowledge of your firefighters enough? Will this protect your firefighters from harm? The answer: It depends. All I can say is never let your guard down and prepare for the unexpected. Wear and use all of your gear, personal protective equipment, and self-contained breathing apparatus (SCBA), and be ready for the worst.

Here are two recent events that will hopefully make you think twice about a simple CO alarm.

It’s 0235 hours. My squad company is assigned with a ladder company to respond to a CO alarm activation in a private house. This is an everyday occurrence and business as usual until we arrive. As we pull up in front of the house, we see people standing outside along with some neighbors (a little strange for 0235 hours). As I open the door of the apparatus, my single-gas CO meter is alarming and it is continuing to increase to 85 ppm. I can also hear the ladder company’s officer meter alarming as we approach each other. We immediately request additional units to respond and the utility company, as this is not a normal response. We proceed to different private houses to investigate and evacuate. We are now getting readings of 300-400 ppm in each home. After investigating multiple homes, it is determined that the underground electrical wires were burning under the street. Power was shut down to the area until it could be repaired.

More recently engine and ladder companies were assigned to a CO detector activation at Boston Market. On arrival, the firefighters entered the establishment with their meters to investigate the alarm in the basement. Members were monitoring their meters as they proceeded down the basement stairs. Both CO meters were still reading 0 ppm, but one officer was carrying an additional meter on which the oxygen sensor was showing a slow decrease down to 20 percent oxygen, which is before the meter’s alarm threshold. Firefighters immediately donned their SCBA face pieces and requested a Hazmat Response. As they continued to investigate they realized that the detector activation was for carbon dioxide (CO2), not carbon monoxide (CO). They noticed a few smaller cylinders of CO2, which they shut down, and then exited the building. Once the squad and hazmat companies arrived, they entered the basement with additional meters, including a carbon dioxide meter. As the investigation continued, a large Dewar containing liquid CO2 was located in the basement that was leaking and partially frozen. The cylinder was shut down and the basement was ventilated. Many restaurants are starting to use liquid CO2 due to the large expansion ratio of 553:1. C02 is considered non-flammable, colorless, odorless, tasteless, and 1.5 times heavier than air. It can only be determined if your department has a meter with a carbon dioxide (CO2) sensor. The only other way to determine a problem is by the displacement of oxygen. There have been many similar occurrences that have caused injuries and death. You can review liquid CO2 leaks that occurred in McDonald’s restaurants in Phoenix, Arizona, and Pooler, Georgia, for additional information.

KEVIN YOOS is a 19-year veteran with the Fire Department of New York (FDNY) and a lieutenant assigned to Squad Company 270 in Queens. He has been working in the FDNY Special Operations Command (SOC) for the past 15 years, and prior assignments include Squad 61, Ladder 17, and Engine 50 in the Bronx. He has served twice as Chief of Department for the Setauket (NY) Fire Department on Long Island, is currently a commissioner of the Setauket Fire District, and has been an active firefighter and officer for the past 26 years. He is a nationally certified Fire Instructor II and is a Deputy Chief Instructor at the Suffolk County Fire Academy. He teaches many programs including hazmat, technical rescue, and shipboard firefighting for the FDNY and also instructs technical rescue programs for the New York State Division of Homeland Security and Emergency Services. He can be reached at


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