VdS-Schadenverhuetung Technische Pruefstelle

Extinguishing systems in existing and new buildings

Effects of the ban on AFFF foaming agents

Fluorinated foam concentrates are banned. Everyone who deals with fire protection has heard this by now.

Text: Eike Peltzer, E.P.FIRE

One obvious reaction is to wait until foam concentrate manufacturers bring effective and approved alternatives onto the market. However, too much hope that this will solve all the problems is not justified. Because there is more to do than just swapping old for new. If you wait and see, you can quickly fall flat on your face if the existing foam concentrate is suddenly no longer allowed to be used. This article provides an overview of the challenges ahead.

The triumph of the AFFF

[1] An overview of AFFF and its mode of action can be found here: https://epfire.de/afff-schaum

Since their invention in the late 1960s, waterfilm-forming foam fing agents (AFFF) have enjoyed a veritable triumphal march. The advantages are obvious: the waterfilm that forms between the fuel and the foam ensures that the foam spreads quickly, suppresses outgassing of the fuel and the fluorosurfactants also help the foam to absorb less fuel - an effect to which conventional hydrocarbon surfactants are susceptible[1].

AFFFs also offer another important advantage for extinguishing systems: as the water film makes a major contribution to the extinguishing effect, the quality of the foam itself plays a less important role. For example, the foaming ratio, i.e. the volume ratio between foam and premix. The premix can also be applied almost without foam via sprinklers.

The differences between fluor-free foam concentrates and AFFF

In fluorine-free foaming agents, the fluorosurfactants are missing, thus the water film - and now it depends on the physical properties of the foam. Good quality is now important. As a rule, this means a minimum level of foaming, and aspects also play a role that no one has heard of or at least no one has thought about. The foam bubble sizes and their distribution, for example. In addition to the two factors of foam concentrate and good foaming, there are others that influence performance. The water application (or application rate) and - especially with flammable liquids - the application method, i.e. whether the foam hits the fuel directly or can gently pour down a wall.

Influence factors on the extinguishing effect of foam

These four parameters foam concentrate, foaming, water application and application method determine the extinguishing success. They can be represented in the form of a pie chart. It illustrates that the individual factors can be compensated for by the others. [2]

The optimum setting of the parameters guarantees both extinguishing success and efficiency. If AFFF is eliminated as an extremely effective foam concentrate in the future, the difference in performance must be compensated for by other factors. The remaining options are therefore: increasing the water application, improving the foaming, e.g. by using other sprinklers[3] and changing the foam application in order to release the foam as gently as possible.

Of course, the foam concentrate also continues to play a role. Manufacturers are currently putting a lot of effort into developing new fluor-free foam concentrates and hardly a month goes by without a manufacturer launching a new foam concentrate on the market. But the foam concentrate is just one of four factors. A clever combination of the four factors is necessary to keep costs as low as possible, especially when converting existing systems to fluor-free foam concentrates.

[2] Incidentally, this illustration is inspired by the so-called Sinner's circle, which shows the influence factors on the result when washing laundry.
[3] Standard screen sprinklers deliver the worst possible foaming. With the waterfilm at AFFF, this was secondary, but is now becoming more important.

Flammable liquids

Flammable liquids pose a completely different category of challenges for all applications. This is because the fuel has a strong influence on the performance of the foam. In principle, this has always been the case, but the numerous tests carried out as part of the testing of fluor-free foam concentrates have shown how great this influence can be. Especially when it comes to polar liquids, i.e. liquids that are miscible with water.

It remains to be seen whether this effect is stronger with fluor-free foam concentrates than with AFFF or whether the issue of fuel dependency is now simply receiving more attention. The fact is that there are some fuels that have such a foam-destroying effect that they can only be effectively combated with significant adjustments to the four parameters.

Retrofitting and building new systems

Anyone who wants to convert an existing extinguishing system or build a new extinguishing system with an admixture of fluor-free foam concentrate faces the following challenges: First of all, the effectiveness of the extinguishing system must be maintained or proven. To do this, the factors mentioned above may have to be adjusted. In addition, there is the disposal and, in particular, cleaning of system components that are to be reused, as well as a number of other technical issues.

Clean the systems

The factors for effectiveness have been described above. Let's move on to cleaning. Cleaning the system is necessary due to the very low applicable limit values. If this were to be dispensed with, the fluorosurfactants from the residual quantities of AFFF would lead to the limit value being exceeded in the new, actually fluor-free foam concentrate. Several companies have already specialized in the cleaning of PFAS-containing extinguishing systems. Expertise is required here in order to achieve the low values on the one hand, but on the other hand to keep the effort and the rinsing water produced within reasonable limits. This is because the rinsing water contains PFAS after cleaning. It must therefore either be incinerated - just like the foaming agent - or the PFAS must be filtered or separated from the water.

The scope of the cleaning measures must also be determined. The foam concentrate tank, the proportioning system and the lines that carry the concentrate are affected in any case. In the worst case, however, lines containing premix may also be affected. At this point at the latest, it makes sense to consider the economic viability of replacing certain components rather than cleaning them.

Practical topics

Practical issues relate to proportioning, for example. On the one hand, it must be considered if a foam concentrate with a 1 % proportioning ratio has been used up to now. While the development of AFFF was so far advanced that high-performance 1 % foam concentrates were available, this is still a rarity for fluor-free foam concentrates. Switching to a foam concentrate with 3% proportioning means that a new proportioner is required and the foam concentrate supply has to be tripled. The lack of space in many sprinkler control centers therefore leads directly to the next challenge.

Keyword: falling temperatures: additives to make the foam concentrate frost-resistant can in turn increase the viscosity of the foam concentrate. This is why many manufacturers refrain from making them resistant to very low temperatures. Whereas -15 °C used to be no problem, today you can be happy if the foam concentrate is designed for -5 °C. This is not a problem in heated sprinkler control centers. But there are still applications where the foam concentrate is exposed to adverse conditions such as frost.

VdS tip

The path to fluor-free foam extinguishing agents is accompanied by the revision of the VdS 3124 “Foam concentrates - Requirements and test methods” guidelines.The fire-physical performance requirements for foam concentrates for use in extinguishing systems have been spun off into the new VdS 3896 guidelines “Proof of effectiveness for foam concentrates”.The VdS 3124 and VdS 3896 guidelines are available for download at vds-shop.de.Our QR codes will take you there directly:

Why are AFFFs actually banned?

Why are we facing these challenges in the first place? The problematic substances in AFFF are called PFAS, which are per- and polyfluorinated alkyl compounds. This is a group of over 4,700 chemical substances that are problematic for the environment because they are extremely stable (also known as “persistent”), can accumulate in the food chain and are sometimes harmful to health. They do not occur naturally, but are produced industrially.

It is their persistence that worries many people. PFAS are therefore sometimes referred to as “eternal chemicals”. They are released into the environment through the production and use of these substances. The harmful effects on health only became known decades later, meaning that the substances are already ubiquitous. They are even found in unpopulated areas such as the Arctic. They are also ingested by humans via food and drinking water and accumulate in the body.

How much time is left?

These PFAS are now banned. In the EU, but also worldwide. However, step by step and, at least so far, only on the basis of individual substances or certain subgroups. This brings with it the next difficulty: it is necessary to clarify which foam concentrate is affected and how much time is left. A general ban on PFAS in foaming agents[4] is currently being worked on at EU level, but is not expected until 2024. So far, the following applies: perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA) and long-chain perfluorocarboxylic acids (C9-C14 PFCA) are regulated.[5] All of these substances can be contained in foaming agents, but whether the limit values are exceeded or not cannot be determined across the board based on the type of foaming agent or the product name. Only a laboratory analysis can really shed light on this. As a rule of thumb, a foam concentrate manufactured before 2015 is more likely to be affected by the bans than a newer foam concentrate. This is because there are actually also AFFFs that are not affected by the previous bans and comply with all limit values. The manufacturers use PFAS in these foam concentrates, which are not (yet!) regulated.

The end of AFFFs will come with a transitional period. The transitional periods for PFOA and C9-C14 PFCA are currently running. If their limit values are exceeded in the foam concentrate, they may still be used until 04.07.2025.

However, this only applies on condition that the extinguishing water is collected and disposed of properly - during regular inspections such as when the extinguishing system is triggered[6].

And proper disposal means incineration in a hazardous waste incineration plant. 04.07.2025 - that means as a rule of thumb: There are just under two and a half years left to convert extinguishing systems that were installed before 2015. That's not much when you consider what needs to be done in this time. Until then, the foam concentrate must be reported if the PFOA limit value is exceeded. If you have more than 50 kg of foam concentrate in total, this must be reported to the supervisory authority[7].

[4] And another one for all PFAS in general.
[5] Regulations of perfluorohexanoic acid (PFHxA) and perfluorohexanesulfonic acid (PFHxS) and their related substances are also in preparation​​​​​​​
[6] A detailed and constantly updated article on the ban on PFAS in foam concentrates can be found here: https://epfire.de/pfas-verbot-in-schaummittel

[7] All the details can be found in this article on the notification requirements for PFOA-containing foaming agents:​​​​​​​


    Converting an extinguishing system to fluor-free foam concentrate is more than just replacing the old foam concentrate with a new one. Maintaining and proving the effectiveness of the system, taking into account the specific fuels, selecting the foam concentrate and adjusting the system parameters, cleaning the system components and, of course, implementing the project all require a lot of work. Measured against this effort, there may not be much time left. Depending on which PFAS are contained in the foaming agent, you could be affected by a ban as early as mid-2025.