Applying foam is another part of the entire foam strategy that if not done correctly, can lead to injury and property loss. So far, we have talked about developing a foam setup by using the proper types of nozzles, appliances and hoselays. We have discussed the types of concentrate and the necessary application rates, and we have talked about expansion ratios and foam drain time. Now, let’s turn our attention to actually applying the finished foam onto the spill or fire.
We have said it previously in this series and it is so important, that we’ll mention it again. As with any potential for fire, we should always be in the habit of supplying the minimum rate of finished foam. For a spill, a lower flow rate may seem adequate, but what if the fuel did find an ignition source? Get into the habit of applying foam at the minimum application rate for your own safety. If the spill is 300 square feet and this calls for 45 gallons per minute (gpm) of finished foam (.15 gpm per square foot) and you apply 120 gpm, then so be it; the threat will be reduced that much sooner.
Also, another key safety point is the need for a backup line, just in case! We do it at building fires, so why not at a fuel spill or fuel fire?
Once the resources are in place and the necessary amount of foam has been brought to the scene, then it is the time for the application. For our purposes, we’ll talk about the means of applying foam to typical spills and fires that the typical municipal fire department engine company would respond to. What is not a part of this series is the response to the large industrial-type settings or port facilities where specialized fire brigades have access to large types and quantities of specialized foam application equipment. These types of incidents, involving large tanks and significant transportation and handling infrastructure, are well outside the range of this article series.
For the typical engine company, the members should be familiar with three types of methods of foam application. Each is similar in the theory that the fuel spill is disturbed the least. Each method allows for the gentle application of finished foam without causing significant agitation of the fuel. No matter what method is employed, this key facet holds true; the agitation of the fuel or product can create a more volatile situation. Therefore, any of the three methods can offer greater safety and effectiveness during a spill or fire. The three methods are identified with slight variations by different sources and each of the three methods may have different vocabulary, but the principle is the same. Take for example the IFSTA / Brady Essentials of Firefighting (5th Edition) textbook and the Delmar Firefighters Handbook (2nd edition). Both of these texts are of great value to the fire service, but each uses a slightly different vocabulary. The three methods of application, based on these two sources, are as follows:
- The Roll-on Method (IFSTA 5th Edition) and the Bank-in Technique (Delmar 2nd Edition)
- The Bank-down Method (IFSTA 5th Edition) and the Bank-Back Technique (Delmar 2nd Edition)
- The Rain-down Method (IFSTA 5th Edition) and the Rain-down or Snowflake Technique (Delmar 2nd Edition)
The Roll-on Method is a simple concept and allows for the application of foam from a relatively close range. The members stretch a foam line to an area and project a straight stream at the ground with the intention of pushing a foam blanket onto the fuel spill. The power of the stream can easily disturb any spill and splash fuel all over responders, possibly with catastrophic effects. To prevent this debacle, the stream strikes the pavement a few feet shy of the actual spill. In a left to right and back again movement of the nozzle, the nozzle team can push a finished foam blanket farther and farther away from them until the appropriate area is covered.