By Joan Leedy, Technical Director, Dyne Fire Protection Labs
Five to ten percent of the samples tested by Dyne Fire Protection Labs do not pass the performance specifications and are recommended for replacement. This reinforces the need for testing firefighting foam at least annually as recommended by NFPA 25, Inspection, Testing and Maintenance of Water-Based Fire Protection Systems.
Section 11.1.1 “Foam concentrate testing shall be conducted annually.”
Section 11.1.1.2 “Samples of foam concentrates shall be sent to the manufacturer or an approved testing laboratory for quality condition testing.”
Let’s look at the most common reasons why a firefighting foam fails the quality condition testing.
- Dilution – Foam systems are designed to mix water and foam concentrate together when activated. At times, the system can fail, and water can inadvertently mix with the foam in the concentrate tank. An example of this would be when foam is stored in a bladder tank. The bladder, by design, is surrounded with water. An unusual but possible occurrence is a rip or tear in the bladder tank which allows water to mix with the foam concentrate. If the foam concentrate is significantly diluted, it will no longer perform as designed,
- Mixing of Incompatible Foams – It is common to top off a system with additional foam concentrate. Foam may have been consumed while testing the proportioning system and need to be refilled. If the same type or brand is not available, a different type or brand may be used during the refill. Some foams are simply incompatible and can render the tank ineffective.
- Incompatible materials of construction – Foam manufacturers generally specify the type of equipment and materials that will be compatible with foam concentrate. If incompatible materials are used, the foam concentrate may not perform effectively. An example of incompatible materials of construction is a system that employs dissimilar metals. Cases have been documented where foam has failed due to the electrolytic action and galvanic corrosion of dissimilar metals. Consult the manufacturers recommended materials of construction for recommendations on equipment to be used with a particular firefighting foam.
- Incorrect Type of Foam – There are many types of foam concentrate manufactured today. Some are designed for class A fire, others for class B hydrocarbon hazards and still others for water soluble flammable liquids such as isopropanol and acetone. It is imperative that foam concentrate in the system is correctly matched to the fire hazard, proportioning equipment and application equipment.
- Age – All foam concentrates have a shelf life and at some point, the surfactants will breakdown and no longer foam. With aqueous film forming foam, many manufacturers estimated the shelf life to be 20 years or more. As the industry switches to fluorine free foams, the shelf life on these new formulations will likely be less than fluorinated foams.
- Viscosity – Foams can increase in viscosity over time and even to the point where proper proportioning will not occur. Viscosity testing is conducted by Dyne assuring that the foam viscosity is still in the range recommended by the manufacturer.
Questions? Contact us today by calling (800) 632-2304 or emailing lab@dyneusa.com.
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