Firefighing Field Notes
By Dominic Colletti

The E85 Threat And Rescue Pumpers
With the growing use of ethanol blended motor fuels in the United States, it’s time for every department to reevaluate strategies regarding how they tackle flammable liquid vapor and fire control on roadways. With a forecast of increasing levels of ethanol in gasoline, from 10 percent on up, and the availability of E85 or E95 in more locations, every firefighter handling roadway vehicle rescue incidents needs to better understand the impact and changes in tactics required to mitigate both an un-ignited ethanol blended fuel spill or shallow-pool fire.

While we will not turn this discussion into a hazmat class, we will give an overview of some key elements that you need to know when planning to respond to an ethanol blended fuel emergency – the kind a fire department might encounter during a motor vehicle accident response or after a small spill from a bulk flammable liquid transport vehicle. And we’ll discuss the types of foam equipment that could be used when planning a new rescue pumper to effectively mitigate ethanol hazards. Note that many of the same types of foam hardware that can be installed on a new pumper can also be retrofitted to an existing rescue pumper.

First, we should all know that there is little doubt that we will more frequently deal with ethanol blends in the future, since its base raw material, corn, is a renewable energy source and because farming and the refining industry required to manufacture the product can employ increasing numbers of people in our homeland as its consumption increases – all of which is a good thing. While ethanol’s economic consequences to companies and workers involved in its manufacture and distribution are positive, emergency responders must be prepared for the inevitable product spill and fire, which can be more challenging than mitigating a straight gasoline flammable liquid emergency.

Straight or 100 percent ethanol, a grain alcohol, is not used as motor fuel today since it is 200 proof alcohol, which makes it fall under government guidelines that include increased taxes and regulation since it could be re-packaged for human consumption. So, it is “denatured” for automotive fuel use by mixing it with 15 percent gasoline, turning it into E85, which eliminates its use for personal consumption because it is toxic.

A Polar Solvent
Ethanol is a clean burning high-octane fuel. One of the challenges involved in suppressing ethanol vapors with foam is that ethanol is a polar solvent and therefore water miscible, which means that ordinary Class B foams (non-alcohol resistant concentrates) will not be effective. Essentially if aqueous film forming foam (AFFF) is applied to the surface of an ethanol fire, the water contained in the finished-foam blanket will drop out and mix with the polar solvent fuel, and the fire will continue to burn. When tackling an ethanol spill or spill fire, alcohol resistant foam (also known as “AR” type foam) is required. Most alcohol foams will form a polymeric membrane, a physical barrier, on top of the alcohol fuel surface. This physical barrier acts to separate the polar solvent fuel from the water in the finished-foam blanket. Therefore the foam blanket destructive properties of the ethanol are thwarted due to the physical barrier of the polymeric membrane.

One challenge in extinguishing E85 involves a dynamic that occurs when water mixes with the product. For example, if, in error, non-alcohol resistant foam such as AFFF were applied to an E85 spill fire, the water in the finished-foam blanket will drop out into the fuel and mix with the polar portion of E85 (the ethanol portion). What happens next is interesting – water dropping out of the foam blanket ends up mixing with the 85 percent ethanol content of the E85/gasoline mix. The 15 percent gasoline (non-polar) does not mix with water and will float on top. After the 15 percent gasoline floats to the surface, evaporates or burns off, you are now combating a pure ethanol fire. In daylight, flames from an ethanol fire may not be visible after the gasoline burns off. Beware – this is extremely hazardous to firefighter safety.

Dual Foam Reservoirs
Most truck committees include dual foam concentrate reservoirs on new rescue pumpers. One tank holds Class A foam, used for extinguishing automobile interiors or other stubborn ordinary combustible materials found on roadways, such as tires, and the other tank carries Class B foam, such as alcohol resistant AFFF.

When designing a new rescue pumper, plan to include at least one foam reservoir, 50-gallons or larger – to hold an alcohol resistant foam concentrate. When purchasing foam concentrate, remember that the more concentrated the foam agent, the more firefighting capability you will have. Simply, you get more firefighting capability from the agent per unit volume as the manufacturer’s foam proportioning rate decreases. For example, a 1 percent x 3 percent AR-AFFF agent is a better choice than a 3 percent x 6 percent agent.

The Proportioning System
The next step is to choose a foam proportioning system. Phone calls to the foam hardware manufacturers are important to verify the following:

What is the gpm foam pump output of their specific foam proportioning system?
What application rates (gpm of foam solution) will each system provide?
Over what gpm operating range and discharge pressure range is the unit designed to perform?
Can the unit satisfactorily dispense high-viscosity alcohol resistant foam concentrates
Is your specific brand and type of foam agent approved by the hardware manufacturer for use in its specific foam system?
What diameter (inside) tubing or piping are required from the concentrate tank outlet to the foam proportioning system to ensure it will work at maximum designed flow?

Can compressed air foam systems (CAFS) be used with alcohol resistant foams for application on flammable liquids? Yes. CAFS have been successfully used for extinguishing flammable liquids in a variety of circumstances. One key use of generating a CAFS finished-foam blanket is for application on un-ignited fuel spills – for vapor suppression. The key here is that with CAFS, the pump operator has the capability to “dry out” the foam blanket, in other words to control the moisture content and drain time of the foam applied to the fuel. A “fluid” or “moderately dry” alcohol resistant finished-foam consistency applied to an un-ignited E85 spill will provide vapor suppression for a longer period of time and have less foam solution run-off compared to a nozzle aspirated finished-foam blanket.

I hope that this brief overview of E85 and discussion on foam systems for rescue pumpers has provided some food for thought for truck committees planning a new apparatus. As ethanol blended fuels become more widespread, the fire service must respond by better understanding the hazards that they pose and also by choosing the best agent and equipment available to tackle the problems encountered during vapor suppression and fire containment activities.