By Rick Markley, FireRescue1 and Fire Chief Editor-in-chief
Mention the use of foam to a group of firefighters and you almost certain to get a range of strong opinions. Some love it, some hate it and many simply don’t fully understand it. To better understand what firefighting foam can and cannot do and what developments are in the pipeline, we’ve brought together four experts to talk foam.
1. What improvements do you expect in foam delivery systems in the next five years?
We will continue to see efforts made by manufacturers directed at making CAFS more appealing to departments. I think they’ll focus on making the systems even simpler to use and maintain and easier for departments to afford.
I also see greater production of the portable CAFS; that is, the backpack style that is starting to gain some traction with the wildland fire community. Those types of systems have a bright future when you think about it.
Meet the Experts
Robert Avsec is FireRescue1′s product expert and a retired fire officer.
Rod Carringer is a firefighter and Task Force Tips’ chief marketing officer.
Jim Cottrell operates Cottrell Associatesand is a member of U.L.’s Firefighting Foam Standards Technical Panel and former chair of IFSTA’s Foam Technical Committee.Eric Combs is the director of marketing forElkhart Brass.
With the fire suppression superiority that CAF has over plain water, a crew of three or four firefighters — each equipped with a CAF backpack — can cover a lot more ground than one pumper. This could have a huge impact in those situations where firefighters are protecting structures, hitting spot fires before they can grow, etc.
Class A foam delivery systems are pretty much bullet-proof and are not likely to change much in the near future.
Class B foam is where most of the system critical issues live. Proportioning accuracy is mission critical in terms of safety and survivability. NFPA, U.L., Factory Mutual Systems, FAA, U.S. Navy and U.S. Coast Guard all have skin in this game.
These entities are not in a crap-shoot when it comes to proportioning accuracy — lives are at stake when it comes to crash and rescue survival and or long-term scene security at crashes, fuel storage tank fires or refinery emergencies.
That said, military, municipal and industrial fire apparatus having onboard foam capabilities now need to be able to accurately proportion the most viscous of alcohol-resistant foams (AR-AFFFs) that are required for managing gasoline/ethanol blends.
If a foam system manufacturer says use a low-viscosity alcohol-resistant foam, it is not likely to be one that will pass a U.L. test fire on ethanol/gasoline blends.
The reason for the low-viscosity recommendation is that some, not all, systems are designed for foam concentrates that have viscosity not much higher than maple syrup. These system pumps do very well with Class A foam and regular AFFF.
In most cases, the thicker the concentrate the better its U.L. 162 fire test listings and the longer it lasts between reapplication, which is a quarter life discussion for another time.
There is no free lunch when it comes to onboard systems. Solution flow rates are generally much higher for B foams than the A foams. In this regard, there is still space for improvement when it comes to Class A/B systems and onboard foam concentrate storage arrangements.
One way of skinning the AR-AFFF foam cat is to use self-inducting master stream nozzles where pick-up tubes are dropped into or connected to a Class B foam cell.
When it comes to hand-line foam appliances, a good old foam eductor comes to mind. Simply screw a new self-flushing eductor on a pump discharge and connect the pick-up tube to the B tank via a pump panel connection and you’re in business.
Newer eductors have no problem accurately proportioning the thickest of AR-AFFFs. Distance to nozzle is a function of hose diameter, not a function of the eductor design. A 100-gpm eductor will send properly proportioned solution 100 feet through 1.5-inch hose, 200 feet with 1.75-inch and 400 feet through 2-inch. If you use a matching 75-psi, fixed flow or an automatic nozzle, the distance increases another 150 feet. Big fire, big eductor! They are now available for fire department users up to 350 gpm.
Foam systems will become more integrated into the apparatus systems that allow for easier, more intuitive operation of foam from a pump operator’s perspective.
Need for systems requiring less maintenance, which is usually due to lack of use. Too many mechanical issues with paddle wheel flow meters, screens that become plugged, and sensors (electronic components) that cause maintenance issues. First manufacturer with the better system wins.
Class A Foam will continue to dominate while Class B will be less popular to municipal agencies and will never be obsolete in the industrial sector.
The effectiveness of foam will be further optimized through the technology in the delivery devises that optimize expansion ratio and reach. We need to be well aware of the application of Class A and B foams with the building popularity of UHP (ultra high pressure systems).
This will be a future aircraft industry standard as it is already part of every USAF and Navy ARFF unit. The municipal fire service is starting acceptance of Class A UHP.
Expansion ratios are really misunderstood. The higher the expansion ratio, the lighter the finished product becomes, meaning there is less mass and therefore less reach. Also, the higher volume of agent equals more mass and will equate in further reach.
2. How will NFPA 11 (foam section) be different in 2015 and what will that mean for firefighters?
There will be increased emphasis on lessening the environmental impact of foam. Current foam concentrations have a minimal impact on the environment, but they’re still a manufactured product and I’m sure there is still new ground for chemists to break on this subject.
A better question could be does anyone really care about this standard past the purchase of the juice? Don’t restrict this strictly to number 11; there are several other foam-related standards, including QPL from the federal aviation folks that matter quite a bit.
This is likely to be driven by changes in environmental regulations. Changes in the U.L. 162 standard and to a lesser extent, U.S. Navy’s F24385, AFFF formulation, which is now an FAA requirement, is more or less likely to affect the NFPA 11 (Class B) standard. Generally whatever happens to the U.L. foam standard eventually happens to NFPA 11.
Difference in flow rates and proportioning ratios involving new Class B fuels and the equipment needed to provide adequate use especially in an emerging UHP line. Also, the agents will have to become more “green” satisfy emerging EPA requirements.
3. Are there any new or modified formulas that will make foam more effective?
The only thing I have run across is a film-forming AR concentrate. Biodegradation remains an issue for many products, as does the real understanding of what a U.L. listing is for manually applied foam versus the wetting-agent listings we see that lead to so much confusion.
This is likely to be a function of research and development after the looming environmental regulations are enacted or settled.
Right now the Class B industry is working on C-6 surfactants taking the place of C-8 surfactants. These are critical to AFFF technology and are likely to be the starting point for an industry-wide reformulation initiative.
They are constantly in development. Ansul, Williams, and Chem Guard are leaders.
4. How much of a factor is cost for fire departments considering when adding or using foam?
Any operational cost is a big deal to any sized department. Fire department leaders need to start looking at the big picture of how they provide fire suppression services. They need to address the use of foam as a primary strategy — the default if you will — not an optional feature to be used in a small number of incidents.
A pumper costs between $350,000 and $500,000, so let’s go with an average price of $425,000. An installed CAFS for that new engine will run about $35,000; that’s roughly 8 percent of the total cost of the apparatus. While that’s not chump change, it doesn’t have to be an add-on to the pumper; it should be part of the basic design.
Do we really need 1,500-gpm or even 1,000-gpm pumps, if we’ve integrated the superior fire-suppression capabilities of CAFS into the basic specifications for the pumper? The question isn’t: “Can we afford CAFS on the new pumper?” but rather: “How can we not afford it?”
Certainly any cost has to be offset with a return on that investment. Folks that use foam as we do easily justify the expense, because we understand the alternative of water-only use based on years’ worth of history.
For a new department just getting into it, costs may preclude implementation as they just know too little or have very limited ROI experience.
It’s about cost benefit. This is more a question of acquisition cost versus replacement cost. If a good Class A foam is sparingly used (3/10 percent or less), it can be quite effective at keeping fires down once knocked down with Class A solution or CAF.
To treat a 500-gallon booster tank at 3/10 percent with Class A foam, it will cost about $25 at today’s prices. At this percentage, the water concentrate ratio is 99.7 parts water and 0.3 parts concentrate.
Class B foam is the larger cost benefit question. The common list price is $40 a gallon for a high quality 3 percent AR-AFFF foam concentrate. At 3 percent, the cost to treat 500 gallons of water is near $600. At 1 percent, the foam concentrate cost is near $200.
The bang for the buck issue is how long does the foam last on a spill. A 3 percent budget brand AR-AFFF will last 5 to 8 minutes before reapplication is needed. A stouter brew will go almost half hour between applications.
Again, it’s about replacement cost versus acquisition cost — very much a buyer-beware issue.
Cost is becoming a more important factor in all aspects of fire protection. Foam continues to offer a strong cost/benefit to departments when the total cost of service provided is evaluated.
Foam has shown ability to improve effectiveness of equipment and personnel in specific applications. We have seen many departments calculate this increase in effectiveness to outweigh the cost of the equipment and materials required for foam production.
Cost is an excuse many agencies use for not using foam. The ability to mitigate incidents faster and safer have to be considered when determining foam usage relative to safety. It is far less costly to use foam than pay for hospital bills.
5. Is the role of foam any different with light-weight construction homes and alternative-fuel vehicles?
Class A foam remains an enhancement to, not a replacement for, needed fire flow. Our old formulas still hold true on structural attack. For AFFF, our biggest changes have been moving to AR type foams for deal with the blended fuels that are today’s reality.
For wood-frame with truss roof and or floor, Class A foam solution or CAF may be just what the doctor ordered before siding and dry-wall is finished. In order for the agent to do its job it has to hit the fuel. Class A foam can play an important role while fires are in contents stage.
Once fire takes control of well-vented framed spaces such as attics, interior, non-insulated walls or floor trusses, you have a fire requiring perhaps three times the application rate as the one holding a confined, furnished space.
Once it’s knocked down, Class A water additives will soak and hold what you have better than plain water.
For alternative-fuel vehicles — those laced with ethanol from as low as 10 percent to as high as 85 percent — are not candidates for Class A foam at any application rate. One must use AR-AFFF on gasoline/ethanol blends.
Foam becomes more valuable when dealing with high fire loads or lower ignition-temperature materials. Today’s firefighters are faced with many more petro-chemical based materials. This drives the need for more effective fire suppression products such as foam.
Any way you slice it, Class A foam makes water work better by simply breaking down the surface tension of the fuel. Water only is like washing your hands without soap. Some of the dirt comes off.
Use soap and we break down the surface tension of the dirt and it is able to be washed away. Response times are more important relative to new types of construction. If the fire burns for a longer time, the structure becomes less stable, and without any extinguishing agent being applied, it becomes more hazardous.
6. Are there times you shouldn’t use foam?
When you don’t have adequate concentrate supply, when there is an electrical source or component to the fire, when you already cannot provide the necessary fire flow, and when you don’t know what you are doing.
Don’t use Class A foam on Class B fires. Their detergent constituents will mix with oil-base products and come up burning. Class B (AFFF) is a good wetter and can be used on Class A fuels at reduced proportioning ratios. Not much suds but good wetting.
Another no-no is using foam on pressure-fed, three-dimension fires. Finally, avoid foam all together on electrically charged equipment.
Class C and D fires. High-volume water applications with foam are counter productive. Foam is wasted as the agent is diluted and washed away.
7. When specifying a foam system, what three things must a department consider?
What types of fires and fire situations account for 90% of the fire incidents in their response areas. Departments need to stop designing fire apparatus for the 10 percent of calls that they could be called upon to extinguish fires.
For those calls that make up the 90 percent, what tactical operations are going to be needed?
How can we best match available staffing with the right CAFS to meet those tactical requirements?
Class A foam for structural attack: what lines do you want, what flows, what foams, and what proportioning method?
Classes B for flammables: what risks, what concentrate supplies, what application rates?
Using a CAF system.
If mostly for Class A firefighting, use an electric discharge side proportioning system. For the once-in-a-career Class B event, use a simple foam eductor. A 100-gpm eductor will manage a 1,000-square-foot fuel oil spill fire and 500 square feet of ethanol if attacked with AR-AFFF.
If Class B use is a high priority, the foam concentrate pump should be able to produce at least 500 gpm of 3 percent solution.
This means you need a 15-gpm foam concentrate pump. A 250-gpm stream will require a 7.5-gpm foam pump. At present there are no AR-AFFFs that will handle ethanol at 1 percent.
Maintenance issues relating to having a Class A and Class B foam tank sharing common system plumbing. If using AR-AFFF in the B tank you might want to forget the Class A foam, because your A foam is likely loaded with alcohol.
Alcohols are what makes most Class A foams wet and soak, the bubbles are the eye candy. A cup of AR-AFFF in the A tank is usually system fatal within an hour, because the alcohol in the A foam launches the alcohol resistant reaction in the tank rather than on the fire. This reaction produces stringy, pizza-like dough, which fouls plumbing, strainers, foam pump or an on-board eductor’s metering valve.
Normal-looking AR-AFFF is thick like a heavy syrup. Some are thicker and can look like gelatin. The alcohol resistant component is a sugar-like material. The more of it, the thicker the concentrate gets. Not a problem for most foam proportioning equipment because these foams thin as they move.
The faster they move the thinner they get, which is why foam eductors work so well with AR-AFFF.
Finally, the onboard eductor system sounds good until you have too much back pressure caused by plumbing restrictions, spoiled AR-AFFF in the metering valve or dry foam concentrate in the eductor supply line. The flush procedure only flushes the metering (1, 3, and 6 percent) valve.
What are the unique situations the department faces in their jurisdiction? How can foam potentially aid the department addressing the situations they face?
Understand the balance of Class A and Class B foams. Too many sales presentations unfairly promote Class A as a mitigating agent for Class B fires. Although it makes the water work better, Class A foam does not provide the extinguishing and vapor sealing properties of Class B foam.
What delivery products are needed to maximize the effectiveness of foam products based on the unique situations? For example, what expansion ratio is optimized based on the type of foam being used. Is CAFS or self-aspirating products more efficient based on type water supply and type of typical fire calls.
Low expansion ratios are required when extinguishing an active fire as the agent needs to be dispersed faster and provide for liquidity and penetration into the burning product.
Higher expansion ratios are needed to insulate areas that have burned to prohibit re-ignition and to provide a barrier to unburned surfaces so they do not ignite. A wet layer is covered by a dry area (higher expansion ratio) to maintain moisture and cooling while preventing evaporation
CAFS is a wholly different application method, application and training than conventional firefighting. Ensure the training requirements are properly budgeted as part of the overall purchase decision.
The lack of training will cause agencies to use more foam in actual incidents than necessary and may ultimately cause the agency to discontinue foam use due to needless expense. Training is highly needed and cannot be neglected.