The Importance of Firefighting Foam Testing

Firefighting foam is a critical component of the fire protection industry. Its effectiveness can mean all the difference between loss and preservation, not only for property, but also for the lives of first responders , families, friends, and the entire community. According to NFPA 25, all foam concentrates are required to undergo annual testing to evaluate the quality of the foam. Understanding the requirements and how to properly navigate the testing process is essential for maintaining safety and compliance.

Dyne Fire Protection Labs, an NFPA Global Solutions Company, specializes in performing these tests in accordance with NFPA 25, helping organizations confirm their foam concentrates are reliable when it matters most. In the first segment of our two-part series on firefighting foam testing, we’ll break down why testing matters, the types of tests typically performed, how to properly collect foam samples, and how to understand your test results.

When Should Firefighting Foam Be Tested?

It’s common to put firefighting foam into service with the hope that it will never need to be used. However, when it is needed, it’s crucial that the foam performs exactly as intended. A simple visual inspection is not enough to confirm that your foam meets its performance standards. While some foam products may have distinctive colors, these can fade or change over time due to environmental exposure and storage conditions. This variability is one of the key reasons why NFPA requires annual testing of foam concentrates to evaluate quality and performance.

According to NFPA 25, section 11.3.1.1, foam concentrates must be tested annually. Following that same section, 11.3.1.2 specifies that samples of the foam concentrate need to be sent to the manufacturer or an approved testing laboratory for quality condition testing. These requirements are outlined in the 2023 edition of NFPA 25.

Note: While section numbers may differ slightly in previous editions, the requirement for annual testing has remained consistent.

Staying compliant with NFPA 25 not only meets regulatory standards but also reinforces the reliability of your fire protection system. Proactively verifying foam performance helps prevent unexpected failures and supports a safer environment for both people and property.

How to Properly Collect Foam Samples for Testing

Collecting a representative foam sample is one of the most critical steps in the testing process. While NFPA 25 outlines the requirement for annual testing, it does not provide specific guidance on the number of samples to collect. This differs from sprinkler system sampling, which is more clearly defined. However, there are established best practices to follow that help confirm meaningful test results.

For larger foam tanks, it is recommended to collect multiple samples, ideally from different depths such as the top and bottom of the tank. Over time, tanks that have been topped off, partially drained, or exposed to temperature shifts may contain foam in varying conditions. Sampling from multiple points provides a more accurate picture of the foam’s overall quality.

Avoid collecting samples from trim piping or small branches of the system. Foam that sits stagnant in these areas is more vulnerable to environmental degradation and is not representative of the foam in the main tank.

To simplify the process, Dyne offers free foam sample collection kits:

• Two-bottle kits are ideal for taking top and bottom samples from a single tank.
• Four-bottle kits are designed for sampling multiple tanks or various points within a larger system.

Tests Performed

Once a firefighting foam sample is submitted to a laboratory, it undergoes quality condition testing. While NFPA does not define “foam quality” in detail, most laboratories reference other recognized standards and industry guidelines. Typically, foam quality is evaluated based on two key performance metrics:

1. Expansion Ratio

This measures the foam’s ability to expand when mixed with water and discharged through a system. A proper expansion ratio results in a thick, stable foam blanket that suppresses fire by smothering vapors and cooling surfaces. A low expansion foam creates smaller, tightly packed foam bubbles on discharge compared to a high expansion foam which creates a blanket made up of larger bubbles.

• Low-expansion foam typically ranges from 5:1 to 10:1.
• High-expansion foam can reach ratios of 1000:1.

2. Drain Time

This measures how long the foam blanket stays intact before beginning to break down. Foam that drains back into solution too quickly may not provide adequate protection and must be reapplied more frequently.

• Most labs measure the 25 percent drain time, which is the time it takes for 25 percent of the expanded foam to drain back into a liquid.
• For high-expansion foams, a 50 percent drain time may also be used.

While expansion and drain time are key performance indicators, quality condition testing also evaluates a foam’s physical and chemical stability. These tests can identify signs of dilution, degradation, or contamination:

• Refractive Index and Density: Lower values may indicate dilution, which can impact expansion and drain time performance.
• Viscosity: Especially important for alcohol-resistant foams (i.e. AR-AFFF). A drop in viscosity can reduce effectiveness and affect proportioning. Excessively high viscosity caused by heat exposure can lead to clogging.
• pH: Abnormal pH levels may signal chemical degradation or contamination and can potentially damage system components.

These properties are compared against the manufacturer’s original specifications. Significant deviations can indicate compromised foam, which may lead to underperformance during an emergency. Identifying these changes early helps confirm your foam remains reliable and effective.

Understanding Your Results

Your foam quality test report offers valuable insight into the condition and reliability of your foam concentrate. Here are the components included in a report from Dyne Fire Protection Labs:

Physical Properties

Results for refractive index, density, viscosity (if applicable), and pH, which can help identify whether the foam has degraded, been diluted, or contaminated.

Appearance

Observations on color and consistency, which, while not performance metrics, can support other findings.

Performance Properties

Pass or fail results for expansion ratio and drain time, which directly influence fire suppression effectiveness.

Film Formation

For foams like AFFF, this section confirms whether a film was formed and includes a spreading coefficient result since film-forming foams are required to have a positive spreading coefficient value.

Overall Result

A summary evaluation of "Pass" or "Fail" based on all test parameters, providing a clear picture of compliance and performance.

Even if your foam passes all criteria, tracking year-over-year results can uncover subtle trends. These patterns can serve as early warnings, giving you time to address issues before they lead to system failure.

Conclusion

Foam quality condition testing is about more than regulatory compliance. It provides confidence that your system will work when it matters most. A fire suppression system that underperforms during an event can result in devastating losses to property and life.

At Dyne Fire Protection Labs, we provide comprehensive foam testing services and expert guidance. From free sample kits to detailed lab reports in 5 business days or less, we are here to help confirm your system stays compliant. Stay tuned for Part 2 of our Firefighting Foam Testing blog series where we will explore PFAS within the firefighting foam industry.