Transitioning sprinkler systems to fluorine-free foam

As regulatory pressure accelerates the move away from firefighting foams containing intentionally added fluorine, building owners and operators are facing complex technical and operational decisions. This article focuses on the use of non-fluorinated foams in sprinkler systems, where performance is influenced not only by the foam itself, but by how it interacts with system design and discharge characteristics.

While fluorine free foams are already proven across many applications, their performance characteristics differ fundamentally from legacy solutions – particularly in sprinkler systems, which were originally designed around different assumptions. As a result, transition cannot be approached as a simple product substitution. Instead, a system level evaluation is required that considers how foam concentrate and equipment interact in real world conditions.

Using the EVA framework (Expansion, Viscosity and Application density), this article outlines the key parameters that determine whether a fluorine free foam will perform effectively, reliably and in line with evolving standards.

Why fluorine free foam is different

Fluorine free firefighting foams suppress fire through a different mechanism than legacy film forming fluorinated foams. Rather than spreading a film across the fuel surface, they rely on forming and maintaining a stable foam blanket that cools the fuel and limits vapor release. In doing so, the foam works by disrupting the fundamental elements required for combustion often described as the fire triangle or fire tetrahedron: heat, fuel, oxygen and the chemical chain reaction. By cooling the fuel, separating it from oxygen and suppressing vapors, the foam effectively breaks this cycle and extinguishes the fire.

Most sprinkler systems are non aspirated (meaning no air is mixed into the spray as it leaves the sprinkler), leading to a low expansion (producing relatively small volumes of foam from the liquid solution). In simple terms, these systems deliver foam as a relatively dense liquid spray rather than a highly aerated foam. As a result, the foam must be capable of forming and sustaining a stable blanket on the fuel surface without relying on added air generated by the system. This places greater importance on inherent foam stability and uniform distribution, as the sprinkler itself does not significantly enhance foam structure during discharge.

Fluorine free foams such as Ansul NFF 331, NFF-332 and Ansul NFF-3H have been developed to operate effectively under these conditions, delivering stable blanket performance at very low expansion ratios. This makes them suitable for retrofit applications where significant system modifications are impractical. The key shift is that performance depends as much on how the system delivers the foam as on the foam itself.

EVA defines system performance

Effective use of fluorine free foam in sprinkler systems depends on balancing expansion, viscosity and application density (EVA).

At a practical level, EVA can be understood as:

• Expansion – how much the foam grows in volume as air is introduced, impacting how well it covers a fuel surface
• Viscosity – how thick the foam solution is, which affects how easily it is proportioned with water, as well as how easily it flows and forms a stable blanket
• Application density – how much foam solution is delivered over an area, determining how effectively a fire can be controlled

Expansion becomes a primary performance driver in the absence of film formation. Products like NFF-331, NFF-332, and NFF 3H are engineered to function at low expansion ratios typically around 3:1. This allows them to perform with standard, non aspirated sprinklers.

Viscosity plays an equally important role. Many fluorine free foams are more viscous than legacy formulations, making consistent proportioning and mixing essential. Our fluorine-free portfolio has been designed to behave in a familiar way from a system perspective, helping maintain uniform foam quality without adding complexity. Additionally, Tyco Fire Products fluorine-free foams have been specifically developed to operate at relatively low expansion ratios – typically between 3:1 and 3.4:1. This makes them suitable for use with non-aspirated discharge devices such as sprinklers, which is essential for retrofit applications.

Application density ultimately determines fire control. While some fluorine free foams require higher densities, NFF 331, NFF-332, and NFF 3H are designed to remain close to conventional sprinkler design densities.

Together, EVA provides a practical framework for aligning foam selection with system capability. It can turn fluorine free transition from a perceived risk into a manageable, engineered outcome.

FAQs

How does fluorine-free foam work in sprinkler systems?

Fluorine-free foam suppresses fire by forming a stable foam blanket that cools the fuel surface and limits vapor release. Effective performance depends on how consistently the sprinkler system delivers and maintains that blanket across the protected area.

Why is expansion critical for fluorine-free foam performance?

Expansion influences foam coverage and blanket stability. Because fluorine-free foam relies entirely on blanket formation, expansion characteristics must align with the sprinkler system’s discharge design and aspiration capability.

What role does viscosity play in fluorine-free foam systems?

Viscosity affects how well the foam concentrate mixes with water during proportioning. Poor or inconsistent mixing can reduce foam quality, impact bubble structure, affect expansion and reduce overall extinguishing performance.