How Safe Are You In Fast Food Establishments?
Part 2 — First Responder Considerations
This is the final article of a two part series about the hidden dangers of carbon dioxide. Part two is geared primarily toward first responders and provides background information about CO2 and when to suspect a leak. Further, it highlights why CO2 is a serious problem today and why it presents unique response considerations for firefighters and other first responders.
All businesses that serve fountain soda are using CO2. There is an increased risk in businesses that serve a high volume of fountain soda. Businesses such as Burger King, McDonald’s, Wendy’s, Applebee’s and 7–Eleven® are prime examples of high volume businesses. A firefighter responding to a call at any location that has a fountain soda system in place must be aware that a potentially toxic environment may exist. This danger is increased if the storage of these cylinders is below grade (in the basement or cellar) as CO2 is 1 ½ times heavier than air and will collect in low lying areas.
Supply hose lines from CO2 cylinders create an additional problem. Supply lines run through ceilings (common above a drop ceiling) and walls and can be found anywhere within the structure. These supply lines are plastic and run from the cylinder to the soda system that dispenses the final carbonated beverage. The danger from leaking supply lines is present even in businesses that have outdoor storage for the CO2 cylinders because the supply lines run inside the building to the soda dispenser. Only the risk of leakage from the tank has been reduced in this case.
Rather than storing CO2 in smaller containers, business owners have turned to using larger storage containers which hold a greater amount of CO2 (typically called Dewars) for their fountain soda systems. There are several advantages to this. Business owners benefit from the ability to buy CO2 in bulk due to the larger capacity tanks. Second, they benefit because employees do not have to change out these tanks as often. In many cases, employees do not have to change tanks at all as many have installed an exterior connection which allows the CO2 vendor to fill the tanks in place from an exterior connection. For responding firefighters, this shift to larger cylinders is a game changer due to the larger quantity of gas stored increasing the danger when a leak occur.
Properties and Effects of Exposure to CO2
At room temperature, CO2 is a colorless, odorless, slightly acidic-tasting, non-flammable gas that is 1½ times heaver than air. While harmless in low concentrations, carbon dioxide becomes toxic in high concentrations. Co2 has an immediately dangerous to life and health (IDLH) measure of 40,000 PPM, which on an oxygen (O2) meter is less than a 1% drop.
According to the Centers for Disease Control (CDC) and the National Institute for Occupational Safety and Health (NIOSH), common symptoms of CO2 exposure include headache, dizziness, restlessness, difficulty breathing, sweating, malaise, increased heart rate, coma, and convulsions.
Situational Awareness
Fire and emergency medical service units responding to medical calls for assistance or unknown odors in this occupancy type should be cognizant that they may be responding to a CO2 leak. It should be noted that CO2 is odorless but has slightly acidic taste which has been confused for an odor. CO2 is heavier than air, and therefore in the event of a leak in an enclosed space such as a walk-in cooler, manager’s office, restroom, employee rest area, and basement are particularly vulnerable to increasing levels of CO2.
As CO2 is virtually undetectable by human senses, the only way to safely monitor CO2 is by using fixed or portable alarm systems. Alarms are available that have been designed for the restaurant industry. The alarm monitors the level of CO2 in the air. Since CO2 gas is heavier than air, it is recommended that the fixed gas detectors be installed at breathing zone level, which is 4 to 6 feet above the floor.
In order to minimize the risk of a deadly CO2 leak, employees in these establishments need to know the risks associated with CO2 gas, should be able to identify early symptoms of exposure, and should be protected by a fixed gas monitoring system. Employees must also be trained in what to do in the event of a CO2 monitor activation.
Operational Considerations
Response units suspecting a CO2 leak must use a self-contained breathing apparatus (SCBA) while operating in a potential IDLH atmosphere and immediately call for a hazardous material (Haz-mat) trained unit with greater metering capability. These units have the ability to check for and verify O2 deficient atmospheres. Haz-Mat trained and equipped companies typically perform atmospheric monitoring for O2, methane, CO and other explosive gases (LEL), but they do not monitor specifically for CO2. When these units detect low oxygen levels in businesses with CO2 in use, they must consider the possibility that elevated CO2 levels exist and use instrumentation capable of reading CO2.
Shutting down the Dewar cylinder
The typical CO2 Dewar cylinder used in this installation is the Department of Transportation (DOT) 4L292, known in the industry as the “292.” This cylinder stores CO2 in its liquid form and is passed through a regulator as a gas to be used in finished products. On the top of the cylinder, numerous valves can be found, many with tubing running from them. Shutting down the value with the regulator will isolate the cylinder supply to the soda system.
Types of Installation
A typical interior installation will have a large supply line hose connected to the cylinder. This hose will lead to an exterior fill connection which is used by the vendor to resupply the CO2 tank, similar to the way a fuel oil truck makes a delivery. The exterior connection can often be found on the exterior wall, closest to the cylinder, provided that it is accessible for a delivery truck to resupply. If the closest wall is not accessible, this fill connection will usually be found at an adjoining exterior wall that is accessible for a delivery. This type of installation is common in areas where real estate is at a premium and the property does not have room on the exterior for tank storage.
A typical exterior installation will have a tank against the side of the building in an area that is distanced from the front of the occupancy, typically behind a chain link fence for security. From the cylinder on the exterior, a plastic tubing supply line will run to the interior of the occupancy to the location of the soda system.
The “292” is a 160 liter cylinder, which can be filled with up to 387 pounds of liquid CO2. Liquid CO2 has an expansion ratio of 553, which means even a small leak in the tubing from a full cylinder can cause dangerous O2 displacement anywhere within a structure.
Lessons Reinforced
> Maintaining situational awareness on every call helps keep responders safe. This is true especially when responding to businesses that use CO2. A CO2 leak may initially be reported as an unconscious patient in a restaurant.
> CO2, like propane, is heavier than air. High concentrations may be found in low lying areas such as the basement or in confined spaces or small rooms within the occupancy. These areas will achieve higher concentrations quicker than a larger area.
> Response units operating at a fire, in which the supply tubing or tank is involved or compromised in anyway, must insure the CO2 tank is shut down to prevent a potentially lethal CO2 buildup.
> While shopping or doing other activities around town, identify and take note of businesses that use/store large amounts of CO2 and log this information into a system that provides it to responding units.
> Frost or condensation on the exterior of a CO2 cylinder is a strong indicator that a leak exists, either in the supply tubing or from the tank itself.
The arrow is pointing to the gauge in the center, which shows how much CO2 is in the cylinder.
The arrow is pointing to the CO2 tubing going up to the ceiling.
The arrow is pointing to the CO2 supply line going to the exterior of the building.
The arrow is pointing to the total contents in LBS when full (387 for this size).
Often the cylinder will be located opposite this wall as long as there is access to this location for the supply truck. This would be a clear indication that CO2 cylinders are located on the interior.
Frank Leeb is a contributor to the Homeland Security (HS) Vortex which is a platform where insiders from the policy, law enforcement, fire service and emergency management fields converge to discuss issues related to Homeland Security.
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