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Haz Mat "Specialist Course"

Foam 109.2 Blended Fuels

Blended fuels combine polar solvents with internal combustion fuels to create a homogenous mixture that reduces impact on our environment. Minimal separation reduces engine issues for prolonged storage inside fuel tanks.

The varying levels of percentage (%) combination of these polar solvents allow “tweaking” of fuel ratio concentrations for a variety of engines to reduce all emissions. These “varying” differences can have an impact on flammable liquid fire suppression techniques especially when Foam concentrates are being used.

The effect of varying concentrations of polar molecules to hydrocarbon fuels causes blended fuels to;

1] Burn hotter

2] Varying vapor pressure

3] Surface tension change

4] Polar attractiveness changes

The NFPA Foam application methods will have to accommodate these changes. When using any of the three (3) types, be aware of such variables as Foam reserve volumes, Foam concentrate type, and the design/purpose of the Foam concentrate you have chosen for your operation. Are you suppressing vapors or extinguishing flame? These may affect your operational procedure.

Having trained personnel as opposed to relying on a fixed system will increase your operational capabilities in most incidents. The trained operator can adapt to issues and concerns as he/she sees them forming to get the desired result. Keeping personnel “up-to-date” towards changes and new trends will ensure a successful mitigation outcome for your emergency.

                             Haz Mat Mike



Foam 108.2 Wetting Agents

Class “A” (foam) is an incorrect term. Class “A” (Wetting Agent) should be the correct one. This is because operational personnel need to delineate the marked difference between classes “A” and “B”. This is akin to referring to all automobiles as “cars”. We know they are all transportation tools, but designed for quite different applications. You would not use a small vehicle to transport large amounts of equipment.

Class “A” Wetting Agents are degreasers designed to reduce surface tension of organic substances so that they can allow the water to “soak” in to these materials reducing the temperature and extinguishing the flames. Class “B” Foam uses the advantage of water surface tension to float across liquid surfaces forming a uniform blanket of finished Foam that also cools surface temperature but mainly provides a smothering affect extinguishing the flames and suppressing future vaporization of the hazardous product.

Herein lays the difference, these are two (2) opposing forms of chemistry that have opposite uses. Once this concept is firmly implemented into your response group, choosing the correct product to attack your hazard becomes simple!

Another factor to include in your operational program is one characteristic of “wetting agents” that is often over-looked. Since these liquids have degreasing properties, it is imperative that you appreciate these liquids are drying out your equipment. After use “re-lubrication” to your pump components, valves, nozzles, and any other appliance that the wetting agents flow through is imperative! Just like any tool, your equipment must have the proper lubrication to continue to function without damage. This is a separate subject that needs careful consideration by you and your equipment maintenance personnel.

If you use great amounts of these products, such as wild-land firefighters do, it behooves you to research these issues closely! Be proactive so that your equipment does not fail on you leaving you unprotected! Develop good relationships with your equipment maintenance staff and regularly discuss and refresh over these needs.

Class “A” wetting agent frequent use by your department should encourage you to have a vigorous relationship with your maintenance staff. Be sure that they too, understand the ramifications of continual use of these “wetting agents”.

The benefits of wetting agents can be seen in the “Foam 108 Class “A” Wetting Agents” article located in the left side-bar archive section of this website. They are numerous and useful as long as “you choose wisely” for the application needed.

                      Haz Mat Mike


Foam 107.2 Application Techniques

When we speak of the implementation of application techniques as we did in (see Foam 107 post) what we are really training the firefighter in is the “practical” application of these techniques. This requires actual hands-on suppression of flammable liquid fires using firefighting Foam and the techniques discussed.

If you do not have access to a training facility that is set-up for flammable liquid firefighting, this can be accomplished using a designated area and “pan fires”. Pans are constructed out of heavy gauge steel, welded at the corners to keep flammable liquids and suppression water confined.

To do this in your local area, apply for a Fire Department “Variance” through your local government and employ the talents of your own DPS (Department of Public Services). If these cannot be done, a trusted local welding contractor can fabricate your “pan”. For multiple students repeating a fire extinguishment, a good place to start is with a 4 to 6 inch wall to the pan. This will allow you many extinguishments without having to halt the training session to empty the pan level. Any size or shape can be made, but a good starting place is to make construction of the pan so that it fits inside a standard pick-up truck box. This makes transportation of your “burn pan” easy for multiple vehicles. One idea we added was to incorporate wheel casters into the fabrication design. However, extra sturdy and heat resistant casters must be used for extreme heat and use.

When teaching the three methods of Bounce off, Bank-In, and Rain down, you must key the avoidance of “plunging”. In all three methods, “plunging” of shooting a concentrated stream of firefighting Finished Foam into a flammable liquid pool will do two things;

1] Spray ignited flammable liquid into the air, thereby spreading the fire, ignition of exposures not currently involved in fire. This can also needlessly endanger nearby firefighters involved in your operation.

2] Plunging disturbs the flow of the Foam blanket which is what you are attempting to create. This “blanket” of solid finished Foam is what causes extinguishment by smothering and cooling of surfaces.

Bouncing Off

When teaching this technique, the most important factor is to use the “object” involved, as a deflector. The object is irrelevant, what is not is the idea and practical theory of breaking the solid stream so that the resulting Foam will “flow” across the pool where the majority of the flammable liquid fuel source is located. This cools and smothers the “feedstock” of the flammable liquid fire, soon to eliminate flame as soon as the fuel source is entirely covered.


When there are no deflectors or objects to “bounce-off” this method can be used by easily striking the ground in front of the flammable liquid pool. This action causes the finished Foam to pile up and form a wave-like roll of finished Foam that continues towards the pool and eventually overlapping the pool edge, continuing to flow across the pooled surface.

Rain Down

This method is primarily used for vertical storage tanks due to the configuration of these high walls. Often it is too hazardous to reach the top of these storage tanks and Foam application must be made from ground devices. Unfortunately, this technique requires larger Foam concentrate resources. Due to the “burn-back” and subsequent loss of Foam from passing through the fire and super-heated gasses, this technique requires longer application with greater volumes of Foam concentrate.

When using this operation, coordinate liquid levels with Tank personnel to be sure your Foam concentrate does not “drain-time” quicker than it extinguishes. If this is not figured in to your over-all attack plan your efforts could overflow the flammable liquid while it is on fire! Great care to watch and monitor tank levels must be made to avoid overflow and protect fire department personnel.

                     Haz Mat Mike



Foam 106.2 Discharge Devices and Nozzles

Air aspiration is paramount in the formation of a proper “Bubble.” It is this structure that affords the firefighter, when properly constructed, to suppress fires, eliminated hazardous vaporization, and eliminated the immediate need for large scale evacuation of “affected” persons. An “Affected” person is terminology that directly refers to civilians in the nearby area of the spill that are untrained residents or business workers that can quickly be negatively affected by these hazards. For Fire Departments and Haz Mat Teams, the ability to quickly evacuate these persons has multiple difficulties for obvious reasons. Manpower, transport vehicles, and evacuee destination location medical needs, are some that top the list. All these complicate your resources and lengthen the time to mitigate an incident.

Low to medium aspiration nozzles or devices are usually sufficient for flammable liquid fires but not for hazardous material vaporization control. For this tactic medium to high aspiration nozzle devices must be used. This is critical for your choice to eliminate the need of immediate evacuation. Choosing the correct device will allow you to “shelter-in-place” “affected” persons reducing your manpower needs and decreasing the incident mitigation time overall. Because you can now concentrate on spill mitigation as opposed to civilian evacuation concerns.

Low aspiration nozzles construct a smaller, wetter, bubble. This bubble absorbs more ambient heat from a flammable liquid fire while still able to hold its structure affording vaporization control over the remaining flammable liquid preventing re-ignition and subsequent “burn-back” resulting in a continued flammable liquid fire. Medium aspirated devices produce a larger “dryer” bubble. This bubble is better for vaporization control as it floats longer, and holds its structure as long as not subjected to flame. Here, the vaporization control time is longer without replenishment and affords confident hazardous material mitigation techniques and longer time frames that are associated with this discipline. 

The choice and or adaptability of your air aspiration nozzle device can yield you desirable or undesirable results depending on which is chosen. Expansion rates (Foam 106) are critical understanding for making this choice. They reflect the mathematics of “how” the air aspirating nozzle or device is functioning. Always refer to these Foam standards under the NFPA 11 section dealing with air aspiration for the appropriate choice.

The number 1 concept to understand is; for proper extinguishment, vapor control, smothering, and elimination of off-site evacuation, Finished Foam MUST be ASPIRATED in order to perform. Without aspiration, large quantities of Foam concentrate shall be wasted without success in extinguishment or vaporization mitigation. Choose wisely, your incident will depend upon it.

   Haz Mat Mike



Foam 105.2 - Foam Proportining

            The key to delivering the finished Foam to its target is the proper proportioning within the hose-line in the form of Foam solution. This occurs “after” the Foam concentrate has been “educted” from its container into the delivery hose-line or standpipe system. The percentage becomes critical in obtaining maximum results to best deploy the finished Foam allowing its particular characteristics to shine. By having the correct “eduction” percentage drawn into the Foam solution maximum suppression and vapor suppression is achieved. When the incorrect setting is used, Foam wastage occurs and your resources are drained at a faster rate thus limiting a positive outcome. This feature in the “system” operation is a critical one balancing resources, cost, successful outcome of your incident all at the same time.

          As NFPA 11 dictates the need for correct proportioning, it does not mention any reference other than to refer to the Foam manufacturer recommendations. This is purposeful as the manufacturer “designs” the Foam Concentrate to be “educted” at specific percentages for its exact purpose. This is critical to the Foams performance and needs to be included into the SOP documents of your Department. When changing from Foam concentrates this feature may be overlooked and cause poor performance. Always be sure that eduction is set for the correct percentage or your attack results may be rendered useless.

          While line eductors are the first choice for suppression operations due to their portability and ability to be used from “Engine-to-Engine” one device for large scale fires should be more closely looked at. These are the “around-the-pump-proportioners”.

          This device functions by using the discharge of a fire pump to create the venture affect, drawing Foam Concentrate into your Fire Service Pump. The benefit of this technique is that “ANY” discharge device on your vehicle or relayed to another device can produce Finished Foam. This has wide reaching capabilities. Finished Foam can be delivered to your target through any large scale master stream device you wish. This is especially useful on large scale tanker truck fires. Facilities that store or contain are volume of Flammables or toxics can also be suppressed using this device. The downside is Foam solution is now contained inside the entire pumping circuit system. This means that EXTENSIVE flushing of ALL intake and discharge pathways will need to be completed before Fire Service Apparatus is returned to normal emergency service. This is sometimes ignored due to exhausted crews after the fire, and disastrous results have occurred. When Foam solution or concentrate is not properly flushed out of your system it can crystalize and block discharges, drain valves, block nozzles, and generally cause future fire suppression pumping actions to fail. Always flush your systems pump and discharge after using this tool to avoid these problems.

          The versatility of the around-the-pump proportioner far exceeds the tedious exercise in proper flushing. One technique that is successful is to drain the pumper after flushing. This will eliminate any crusty issues from forming preventing future operations. Follow this procedure at a minimum;

1] Flow water through all discharges and intake until clear of Foam solution

2] Fill all intakes, discharges, and tanks with clear water

3] Drain the above until empty and no longer dripping (this takes time)

          You may want to add to this procedure to enhance your safety, this is fine, just allow enough time for all the above operations to be done properly to prevent any future clogging issue.

                                 Haz Mat Mike