The first hazard that comes to mind when thinking about large scale ovens and steam kettles is burning or scalding injury. Carbon monoxide poisoning is just as dangerous but less understood, so oftentimes proper prevention methods are not followed. In the United States, this results in over 20,000 emergency room visits and over 400 deaths a year. Before we get to the case study and poisoning prevention methods, we need to know what CO is, where it comes from, and why it is poisonous.
As its name implies, carbon monoxide is a molecule consisting of one carbon atom and one oxygen atom, and is often referred to as CO, it’s molecular formula. It is formed when a fuel burns, but doesn’t burn completely. This is called incomplete combustion. Complete combustion results in the formation of carbon dioxide (CO2). See how the difference is just one oxygen atom? That’s the incomplete part! If the fuel had access to more oxygen, the reaction would have gone further, but for one of several reasons, not enough oxygen was available and we’re left with CO.
So, why is CO so dangerous? One word – hemoglobin. Hemoglobin is the compound in your blood that brings oxygen from the lungs to all the body’s tissues and returns carbon dioxide from those tissues back to the lungs to be expelled. The problem is that hemoglobin loves CO!!! When CO is present in your lungs, hemoglobin snatches it up and doesn’t want to let it go. It will choose CO over oxygen every chance it gets. So, no oxygen gets to your tissues and carbon dioxide doesn’t get removed. If this happens too much, you get sick. You may even die if the CO levels in your blood are high enough.
As an example of a CO-related incident, Warren investigated an instance of CO poisoning at a catering kitchen. Several people began to feel ill and Emergency Services were called. They advised evacuating the kitchen and dispatched the fire department and EMS. Fortunately, there were no fatalities. Measurements were taken on some of the equipment and two of the ovens were found to be generating CO at higher than normal levels.
The Warren investigation uncovered three factors that caused the CO concentration in the kitchen to reach dangerous levels. The first issue was that the ventilation hoods were not operating. Even properly functioning burners will generate small amounts of CO. For this reason, ventilation hoods should always be used when burners are on. The second issue was lack of burner maintenance. Debris was partially blocking the burner which prevented enough air from mixing with the natural gas for complete combustion. The last issue was that one of the steam kettles was being fueled with propane when it was designed to run on natural gas. Burners are designed to mix fuel and air at specific ratios to prevent CO formation. Switching to an alternate fuel is dangerous, in this regard.
So be mindful of CO generation and follow proper prevention procedures to minimize the concentrations in your space. Some sources of information to help you in this endeavor:
- National Fire Protection Association (NFPA) 96
- International Fuel Gas Code (IFGC)
- International Mechanical Code (IMC)
Oh, and don’t get burned, either!!
Jennifer Morningstar, PE has 19 years of industrial experience. Her areas of emphasis include chemical release & exposure, OSHA process safety management, industrial accident investigation, fires & explosions, and scope of damage/cost to repair analyses. She spent 16 years working at a polyethylene terephthalate (PET) manufacturer. She is an OSHA-trained Process Hazard Analysis study leader and completed Root Cause Failure Analysis training to become an Incident Investigator. Jennifer authored procedures for lockout/tagout and confined space entry. She has experience as an energy management consultant in a variety of industries including mineral extraction, pulp & paper, animal harvesting & packaging (including rendering) and grain milling. Jennifer holds a Bachelor of Science Degree in Chemical Engineering from Virginia Polytechnic Institute and State University as well as a Masters of Business Administration from the University of South Carolina.