By Bella Kelly, Quality Technician III, Dyne Fire Protection Labs
NFPA 25 recommends firefighting foam concentrate be tested annually to check the quality condition of the foam. The “Overall Result” on a Dyne Fire Protection Labs foam report will specify whether a sample passes or fails this testing, but this only provides limited information about the condition of the foam. Understanding the details of your report can provide helpful insights into how a sample ages over time or clues as to why a sample may be failing.
Requirements
NFPA 25 states samples of foam concentrate shall be sent to the manufacturer or an approved testing laboratory annually for quality condition testing and to confirm the product meets the manufacturer’s specifications. Therefore, when possible, Dyne uses the manufacturer’s product data sheet to determine the testing requirements. If the specific product is not known or information is not available from the manufacturer, Dyne will look to other recognized standards to obtain generic requirements.
Physical Properties
The results are split into two sections: physical properties and performance properties. Physical properties are not a measure of performance and therefore will not typically cause a sample to fail, apart from extremely low viscosities or out of spec pHs for samples tested to certain standards. However, an issue impacting the physical properties may eventually be reflected in the performance properties as well, which could lead to a failing report.
“In Spec” values are within the range of the manufacturer’s requirement, and “Out of Spec” values are outside of the range. If manufacturer requirements are not available, the physical property result will be “Info Only.” An out of spec test result is not necessarily cause for alarm, especially if the performance properties determine that the quality of the foam is not negatively affected yet. However, if all or most of the physical properties are out of spec, further investigation could be useful. If all the values are too low, the sample could be diluted with water. If all the values are too high or completely outside the specifications, it is possible the sample is either contaminated or a different product than specified. Physical properties should also be relatively consistent over time, so if they are drastically different from one year to the next, it may warrant an investigation of the foam for the possibility of dilution, degradation, or incorrect product information.
Performance Properties
Performance tests are designed to evaluate a few benchmark requirements that can impact the foam’s ability to perform effectively in a fire. These tests reflect the foam’s quality and are therefore evaluated as pass/fail. If a sample fails a performance property, it will typically fail the overall result and further investigation or replacement is recommended.
Since NFPA doesn’t provide a detailed definition of “foam quality,” it is typically evaluated by measuring the expansion ratio and 25% drain time. Expansion ratio measures how well a sample forms a foam blanket when mixed with water and discharged. If the expansion ratio is failing, there are concerns about the foam’s ability to form a blanket that can smother vapors and suppress a fire. 25% drain time measures how quickly that foam blanket breaks down and drains back into a liquid. A failing drain time suggests the performance has been compromised as the foam blanket may not be able to maintain coverage until a fire is fully extinguished. Different foam types have different requirements for expansion ratio and 25% drain time, so it is crucial that the correct product information is provided on the paperwork. Incorrect product information can lead to a sample falsely passing or failing under requirements that are not applicable.
The spreading coefficient is only reported for film forming foams such as AFFFs. These foams were listed with film formation capabilities to provide an extra barrier of protection in addition to the foam blanket. Film forming foams are defined by NFPA 11 as having a positive spreading coefficient, so the report evaluates spreading coefficient as “Pass/Fail.” Samples that pass Dyne’s film formation test with a full film must have a positive spreading coefficient to do so and therefore meet the requirement without the spreading coefficient needing to be measured. Samples that do not form a full film could have either a positive or negative spreading coefficient, so it must be measured in those cases. The film formation test will be evaluated as “Info Only” as it is not directly correlated to a requirement but can provide important insight about the condition of the foam.
The overall pass/fail result determines whether further investigation or replacement of a foam concentrate is advised. Understanding the details of the report can help you understand how the foam product is changing over time and identify future complications early.
If you have questions about your report or how the results relate to foam performance, please contact Dyne Fire Protection Labs at (800) 632-2304 or dyne.lab@nfpaglobal.com and we would be happy to walk through your report with you.