THE PROS AND CONS OF CLASS A FOAM

THE PROS AND CONS OF CLASS A FOAM

The advantages and disadvantages of Class A foam as a structure firefighting tool have not been identified on a national level. While Class A foam has gained acceptance in some areas of the country and in certain facets of firefighting, it is not used nationwide. Since it is used on such a limited basis, it is very important to research the advantages and disadvantages of Class A foam before implementing a Class A foam system.

This article represents a compilation of data on the use of Class A foam as an extinguishing agent for structure firefighting. It is not the intent of this article to recommend that Class A foam be used, but rather to provide an “issue checklist” for departments that are using or are contemplating using Class A foam in structure firefighting.

BACKGROUND AND SIGNIFICANCE

The use of Class A foam has been tested and proven in wildland applications through a series of studies by the U.S. Department of Forestry, the California Division of Forestry, and the Boise Interagency Fire Center. There also has been an increased emphasis on the use of Class A foam for structure fire suppression during the past three years. Interestingly, Class A foam or similar agents have been available for more than 20 years, but their use as a structure firefighting tool only recently has been widely discussed. This is due to the development in recent years of advanced induction methods that allow for more accurate injection and greater expansion of the foam product.

Class A foam now is in use, on a trial basis, in the Boston (MA) Fire Department. Also, the Ponderosa Volunteer Fire Department near Houston, Texas, has had a system in place for more than a year, with much success. Tests to determine the effectiveness of the product have been conducted in Maine, Virginia, North Carolina, and Massachusetts. Many questions have not been answered in the research to date.

PROCEDURES

The research for this project was conducted at the National Emergency Training Center’s Learning Resource Center in Emmitsburg, Mary land. Our sources w ere articles from magazines, journals, and fact sheets; John Ottoson, fire data analyst, United States Fire Administration; videos from Monsanto Company, Wildland Fire Division; interview’s; and a sample survey. The interviews were conducted with Ken Farmer, director of North Carolina Fire Training Services; Lonzo Wallace, assistant chief of the Fort Worth (TX) Fire Department; Jim Cottrell, president of Cottrell and Associates, a fire equipment marketing company; and A1 Morganelli, president of Fire Industry Research Marketing. The survey for this project was performed by polling the 32 members of the National Fire Academy’s (NFA) Development Class of March 1992; this represented a sampling of fire executives from across the United States.

The materials were gathered during the NFA’s development class. Our research substantiates the stated problem that the use of Class A foam is not widely accepted or used by the majority of the nation’s fire departments. This hypothesis was supported by the results of the survey: Of the 32 fire executives polled, 66 percent have not pursued the use of Class A foam for structure firefighting.

We then analyzed and summarized the data. A summary of the advantages and disadvantages of using Class A foam follows.

ADVANTAGES OF CLASS A FOAM

• Numerous tests from around the country using actual structure fire environments have shown that the fire knockdown time of Class A foam is less than that achieved with plain water. It is estimated to be three to five times faster.
• The rate of agent application required is significantly less, and the total number of gallons of water required for extinguishment is less than that needed with plain water. For this reason, rural fire departments probably have the most to gain by using Class A foam, since less water will have to be delivered to the fire front. Also, as water prices escalate, concerns about water conservation may force fire departments to consider alternatives such as Class A foam.
• In foam produced with a compressed air foam system (CAFS), the bubbles are tightly packed, the transfer of heat through the foam blanket is
• more even than that with other foams, and the controlled release of water in the foam appears to be more effec-
• The use of Class A foam appears to be a possible innovation in residential sprinkler systems, especially when faced with a limited water supply.
• Class A foam concentrate is a hydrocarbon-based surfactant that improves the wetting and penetrating capabilities of plain water because it reduces water’s surface tension and has an affinity for carbon-based materials. (See sidebar on page 64.)
• Class A finished-foam adheres to vertical surfaces, thereby allowing more of the water to contact a greater area of heated surfaces.
• Class A foam can be used in a direct fire attack or as a backup line to a conventional water attack line.
• Class A foam can be applied five to 60 minutes before the fire’s arrival and provides excellent exposure protection.
• During the extreme wildland fire season in the summer of 1988, the buildings at Yellowstone National Park were protected by a CAFS operated from a fire engine traveling slowly down the road in advance of the fire front’s arrival. The foam helped protect the structures during the incident.
• There is less chance of building collapse from water runoff accumulating in the structure when using Class A foam.
• An effective Class A foam solution or finished-foam requires less concentrate than conventional Class B foam. Class A foam proportions generally are in the 0.3 percent to one percent range. Class A foam, when used regularly, is economical.
• Class A foam can be mixed by various methods: by batching (adding concentrate to tank water), by eduction, by using a side discharge proportioned or by a CAFS.
• Class A foam can be generated by conventional, low-energy’, and highenergy sources. Conventional smooth-bore, fog, and automatic nozzles can apply foam solution either without bubbles or with limited bub-
• hies created by nozzle turbulence and air entrainment. For a low-energy system, the fire pump and an air-aspirating nozzle are used to create the foam from the solution in the line. A compressed-air foam system is used to produce the high-energy system. Departments can enter into the Class A foam issue with whatever resources they can afford.
• The use of Class A foam results in less water damage and reduces insurance losses.
• Application of compressed-air Class A foam results in less firefighter fatigue—air is injected directly into the hoseline, making the hoseline lighter (the weight of the air-finun-water mixture per unit volume, naturally, is much lighter than plain water).
• The application of Class A foam has been shown to be environmentally safe and reduces water runoff.
• Like other foams, Class A foam produces a blanket effect that reduces
• generation of flammable gases, helps to exclude oxygen, and cools the surface.
• The shelf life of Class A foam concentrate is 20 to 25 years.
• Class A foam is very effective for overhaul and rekindles, and for attic and grass fires.
• Class A foam improves the chances for a successful investigation, since there is less disturbance/damage caused by the fire stream.
• Class A foam provides a visual verification of agent application on the fire.
• Class A foam appears to affect three sides of the fire tetrahedron: oxygen, fuel, and heat.”

DISADVANTAGES/OTHER CONSIDERATIONS

There are some disadvantages to adopting Class A foam for fire department applications. The following is a series of items that should be considered and weighed during the evaluation of this product.

• Several studies referenced the corrosive aspects of Class A foam in a
• 100 percent concentrate. This corrosiveness impacts valves and seals in a pump system. It requires that additional preventive maintenance (flushing and rinsing clean) be done on all pumps, hoses, nozzles, and related equipment. This would result in additional time before the fire company could return to active service.
• Studies by the U.S. Department of Agriculture Forest Service reflect the need to provide protective equipment for personnel using Class A foam. This equipment should include eye goggles or shields, waterproof gloves, protective turnout gear or coveralls, and leather or rubber boots. There is a noted problem of splash back of foam in direct highpressure applications to vertical walls or on pavement. In addition, inhaling the foam vapor can be irritating to the upper respiratory tract. In a study done by Norecol Environmental Consultants, Ltd. in 1989, it was stated that, “Laboratory tests of five fire foams indicate that they can cause eye irritation, contact dermatitis, and sensitization dermatitis.” A review’ of sample Class A foam material safety data sheet (MSDS) studies is detailed. Obviously, ingesting large quantities of 100 percent concentrate would endanger your health. In the application and use of the product, there also is an inherent danger of injuries to personnel due to falling or slipping in the foam product during attack and salvage and overhaul operations. Finally, it is important for firefighters to wear SCBA and protective clothing to prevent breathing vapors of products of combustion. Care must be taken to reduce and limit injuries.
• MSDS information reflects that Class A foam will crystallize and separate if stored in temperatures below — 10°F. In some areas of the country this is a major concern.
• Several sources reflect that there is an obvious increase in the residual radiant heat contained in a structure after extinguishing a fire w ith Class A foam, in comparison with a structure extinguished with water. This was noted in tests completed in North Carolina by Jim Cottrell and Ken
• Farmer, as well as in John Liebson’s article in the July/August 1990 issue of the Voice.
• According to Farmer and Wallace, since tests have demonstrated that the direct application of foam on a flame results in rapid reduction in the foam blanket, adjustments must be made and personnel retrained in application techniques.
• Low-pressure application increases the chances of hose kinks. Experience at the Fort Worth (TX) Fire Department concerning this issue reinforces the fact that hose kinks significantly reduce the pressure in the hose.
• Should the foam-generating mechanism break down —for w hatever reason —an interior structure attack using a low-pressure stream or CAFS could leave the attack team with an insufficient water flow that provides limited protection and decidedly less than the critical flow rate.
• A review of the MSDS on Class A foam reveals that spills of material should be collected for disposal. The suggested method of disposal is incineration. A spill should be collected with absorbent materials and physically removed with a shovel. Spilled product should not be flushed into storm drains or drainage ditches. Also, equipment should not be flushed near domestic or natural water supplies, creeks, rivers, or bodies of water.
• Training is a vital element in the safe and effective application of Class A foam in structure attack. Most studies recommend that personnel receive at least two to three days of training on this new approach. Texas A&M University conducts a weeklong x)l. Initial development of a training class on the use and operation of Class A foam systems by the North Carolina Community College Fire Training Services is estimated at 24 class hours, including hands-on application and field exercises.
• Two key elements in the use of Class A foam are the specific percentage of foam mix ratio and the type of
• nozzle to be used during application. Neither of these issues has been clearly defined. A guide based on fuel type and consistency of foam needed was established by S. Raybould in 1990. His description is a visual perception that is vague and needs more measurement. Testing by Ron Rochna of the Bureau of Land Management (U.S. Department of Agriculture) in Boise, Idaho, indicates that at a mix of above
• 0.5 percent foam concentrate, the surface tension of the water begins to rise.

Several sources noted the use of various nozzles such as fog nozzles, automatic nozzles, and other foamgenerating brands. To date there are no conclusive studies that show which nozzle is the most efficient. One report states that there is no need for a nozzle with the use of a compressed-air foam system.

• To date there are no developed national standards for using and applying Class A foam to structure fire attack. The NFPA Fire Department Equipment Committee began developing minimum standards for this equipment in February 1991. As of this printing, no such standards have been distributed for public comment.
• At this time, the Insurance Services Office does not grant any increase in rating or points if a department uses a Class A foam system. Several agencies are planning to approach ISO after the NFPA takes more specific action.
• No available studies were found to address the effects on ventilating a structure fire during which Class A foam has been applied. Additional research is also needed to determine the effect of positive-pressure ventilation during a Class A foam attack.
• Recent developments in the fire service have provided firefighters with a much improved protective envelope. New turnout gear, improved SCBA, more heatand impactresistant helmets, and full head and face protective hoods have resulted in a potentially overconfident firefighter. This equipment, coupled with the seemingly “perfect” fire suppression agent Class A foam, could create a scenario where an inadequately trained or inexperienced firefighter could penetrate too deep into an interior fire and be overcome by flames, heat, or smoke. Again, the need for training—and experienced attack team personnel —is evident.

RECOMMENDATIONS

The research from all of the resources indicates that the advantages of using Class A foam significantly outweigh the disadvantages. More widespread acceptance and effective use of Class A foam depend primarily on the following recommendations:

• Developing standard operating procedures for fireground tactics such as ventilation, attack, use of nozzles, handlines, and protection of exposures; flow rates, application rates, and percentage mix levels for
• specific attacks and structures; maintenance of pumps, seals, hose, nozzles, turnout gear, and injection and compression systems; health and safety protection for personnel; environmental spills and leaks as well as clean up and disposal of Class A foam concentrate; and storage of foams such as containers, rotation of stock, and protection against severe weather conditions.
• Developing a standard on mixing procedures and terminology.
• Developing a standard on various
• nozzles that could be used to apply Class A foam.
• Developing a written model specification for the design of various Class A foam systems, to include retrofit, new apparatus, environmental aspects, installation and maintenance of air compressors, and emphasis on ease of use.
• Developing a comprehensive national training program to be conducted in all states/local regions that adopt Class A foam systems.
• Adopting NFPA standards for
• Class A foam and related equipment, based on research and study instead of vendor participation.
• Establishing and conducting scientific research and testing methods to evaluate and determine the effectiveness of various Class A foam applications.

One theory that recently has surfaced is the result of the dramatic changes in the fire load of a typical 1990s room versus the typical fire load of a 1950s room: There is a need to revisit initial fire flow requirements for an effective fire attack. The Royer/ Nelson formula for initial fire attack was developed in the 1950s. Since current fire loads have dramatically increased, so too have the initial fire flow requirements. However, most fire departments still use the Royer/ Nelson formula to calculate initial attack capacity. The theory supports the need to increase our initial attack flow to three times that used on a normal structure fire. This theory states that the same amount of water would be used on a fire but that the application rate should be tripled.²⁰

While the fire service should continue to expand its knowledge of Class A foam in the structure attack mode, we should not do so at the expense of readdressing the current “plain water” attack methods relative to the modern fire environment *

Endnotes

1. Liebson, J. “Continuing Development in Class A Foams and Compressed Air Foam Systems.” Voice, 1992; 21 (1), 18-20.

2. Liebson, J. “Is Water Really the Answer? New Foams May Be Better, Part II.” Voice, 1990; (7), 24-25.

3. Bethune, F.J. A Study on the Effectiveness of Ground Applied Compressed Air Foam System (CAES), (Report No. 17558). National Fire Academy, Emmitsburg, MD, 1990.

4. Blankenship, P.L. “Foam: Should We Use It?” American Fire Journal. July 1991; 45-49.

5. Blankenship.

6. Ibid.

7. Ibid.

8. Ibid.

9. Ibid.

10. Ibid.

11. Ibid.

12. Raybould, S. “The Basic Use of Class A Foams with Aspirating Nozzles on Wildland Fires.” Foam Applications for Wildland and Urban Fire Management 1990; 3 (2), 3-5.

13Ibid.

14. Material Safety Data Sheet: Phos Chek WD881 Fire Suppression Foam Concentrate (MSDS No. M00013364). St. Louis, MO.

15. Bethune.

16. Raybould.

17. Abernathy, D. “There Are More Than CAFS in Texas . And That’s No Bull.” The California Fire Service, Mar. 1990.

18. Liebson. 1992.

19. Davis, Larry. “Class A Foams.” Firehouse, Apr. 1991; 49-50, 75.

20. Phone interview, Jim Cottrell, president, Cottrell and Associates, March 1992.