Understanding why Fire Fighting Foams can Fail
As recommended by international standards such as NFPA 11: 2016 and BS EN 13565-2:2009, Fire Fighting Foam Concentrates should be inspected and tested at least annually by a certified laboratory, as part of your fire fighting Foam maintenance programme.
Modern, high quality Foam concentrates are incredibly stable, and are excellent candidates for long-term storage with minimal or no effects on performance. Most Foam concentrates offer a shelf life of up to ten years when stored in the correct conditions. However, the performance of a Fire Fighting Foam can be compromised by many different factors which include; dilution, contamination, extremes of temperature and system failure.
During the Foam testing process, nine different attributes of the Foam are looked at and tested against different International Standards. Fire Fighting Foams can fail these tests for a number of different reasons. Understanding how and why a Foam deteriorates and degrades, can help you not only better maintain and protect your product; but also help prevent any failures in the future as well.
Dilution & Contamination
Dilution is one of the most common reasons for test failure. For example, if a tank is not properly insulated, water can penetrate it, potentially diluting the Foam concentrate and altering its characteristics, which could ultimately reduce its fire fighting ability. To avoid any contamination or dilution, ensuring you have a properly designed storage system which utilises isolation and backflow prevention valves is essential, as these valves are specially designed to avoid inadvertent liquid spoliation.
Another common mistake, which can result in the failure of a Foam during testing, is the mixing together of incompatible firefighting Foams or different brands of Foam.
NFPA 11 standards recommend that two different types of Foam should not be mixed together in storage. Each manufacturer has its own formulation and mixing different formulations together could lead to chemical reactions to occur, which in turn could affect the Foam’s integrity and effectiveness. For example, if an Alcohol-Resistant Foam was mixed with a freeze protected Foam Concentrate, it is likely to alter the polymer in the solutions, which could result in a massive reduction in the Foam’s overall effectiveness and performance. It could also plug the proportioning hole and prevent the Foam Concentrate from mixing with the water supply correctly.
In addition to contamination and dilution, the temperature at which the Foam is stored at is also hugely important. Each manufacturer issues guidelines and recommendations for storage temperatures based on their individual formulations. Failing to follow these guidelines can have an adverse effect on the Foam, reducing is overall lifespan.
Both, excess heat as well as severe drops in temperature can cause many issues for Fire Fighting Foams. Like mixing different concentrates, heat can also cause reactions to occur within the Foam, forcing some ingredients to break down or separate. For example, if the surfactant in a Foam breaks down, it could massively decrease the Foam’s performance in an emergency. Care should also be taken to avoid any possible freezing of the Foam as constant freezing and thawing may have negative effects on Foam Concentrates. Although, many manufacturers claim there’s no loss in performance in their products after freezing, we’d always recommend either stocking a Low Freeze Foam (LF) or routinely carrying out inspections after each thawing process to ensure no separation has taken place.
Lastly, it’s hugely important to ensure that any Foam sample being tested is representative of the storage tank as a whole. If a Foam Concentrate is contaminated or degraded, samples taken from the top and bottom of a storage tank are likely to have vastly different physical properties. In this instance, it’s recommend that two individual samples are taken, one from the bottom of the tank and one from the top. Alternatively, if only one sample can be taken, it’s important to circulate the tank and obtain a composite sample. An inability to obtain an effective sample can cause delays and failures during the testing, so it’s important to follow sampling instructions and complete the specified steps when sampling Foam.
Oil Technics (Fire Fighting Products) Ltd., operates an independent Foam Testing Laboratory which offers comprehensive Foam Testing services as well as the supply of field Foam Test Kits and Equipment.
In addition, our website www.foamtesting.com has extensive online resources, including guides for how to take your Foams, FAQs and example Foam Test Reports etc. Our dedicated laboratory team are also always available to answer any queries you may have.
For more information about any of our Fire Fighting products or Foam Testing Services, please visit our website: www.foamtesting.com or call our team on: +44 (0) 1561 361515