AMP8 and Fire-Resistant Duct Sealing in the Water Industry – Why Pink Foam Must Be Eliminated
As featured in Pump Action Magazine (Page 21)
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The Shift into AMP8: Building for Long-Term Performance
As the UK water industry steps into AMP8, the focus is no longer just on delivering new assets. It is about building infrastructure that is safe, resilient and designed to perform over decades of operation.
Yet one of the most critical details on water and wastewater sites is still too often underestimated: how cable ducts are sealed where they penetrate walls and structures. In environments where fire, methane, chlorine, hydrogen sulphide, water ingress and microbial attack are everyday realities, duct sealing is not cosmetic. It is a frontline defence for people, assets and operational continuity.
What WIMES Is Really Asking For
The WIMES 3.02 (2019) specification is explicit in its intent. Where fire resistance is required, Clause 6.4.3.2 (b) calls for:
“An approved fire-retardant, gas- and watertight sealing system, comprising insert sleeves to ensure cable separation and a silicone-based sealant.”
This wording is deliberate. WIMES is not describing a can of foam or a single filler material. It describes a designed, engineered system that manages fire, gas, water and long-term asset integrity together.
Why Thermal Conductivity and Resistance Matter for Duct Sealing Systems
When cables pass through ducts, the material used to seal them plays a crucial role in managing heat dissipation. Materials with high thermal resistance can trap heat, causing cables to overheat and reducing their performance in a process known as cable de-rating.
On the other hand, sealing materials with excellent thermal conductivity help disperse heat effectively, ensuring cables operate safely and efficiently. This is particularly relevant when discussing the concept of non-adiabatic conditions, where heat transfer between a cable and its surroundings directly impacts performance.
Fire Sealing Requires Tested Systems – Not Expanding Foam
It must be stated clearly: expanding foams, particularly pink ‘fire’ foams, have no place in fire-resistant duct sealing on water utility sites.
While they may fill a void, they are not system-based solutions. They do not provide controlled intumescent behaviour, they degrade in wet and contaminated environments, and they offer no reliable resistance to toxic gases.
They do not meet the intent of WIMES, nor the risk profile of AMP8 water assets.
Introducing DuctSeal FR – Engineered for AMP8 Assets
DuctSeal FR, manufactured by AC Cable Solutions, is a British-made fire-resistant duct sealing system developed specifically for high-risk utility environments.
It is already used extensively across water and wastewater sites where compliance, safety and longevity are critical.
At its core, DuctSeal FR combines fire-resistant Fybrid technology with engineered cable separation, working together as a single, tested system.
The seal is formed using GreyStuff® or RedStuff® fire-resistant Fybrid sealants, combined with FireStuff® Fire Sleeves, manufactured using a specially formulated intumescent granulate.
Under fire conditions, both the sealant and fire sleeves expand in a controlled manner, actively sealing around each individual cable while maintaining separation.
Unlike many traditional fire-stopping solutions, DuctSeal FR is non-adiabatic. At a seal thickness of just 25 mm, thermal resistance is extremely low, resulting in minimal cable de-rating and preserving the cable’s full current-carrying capacity.
What Does Non-Adiabatic Mean in Duct Sealing?
Non-adiabatic systems, like those using GreyStuff or RedStuff, promote heat dissipation, reducing the risk of overheating and maintaining the cable’s current-carrying capacity.
In contrast, materials with high thermal resistance trap heat, creating more adiabatic-like conditions and increasing the likelihood of cable de-rating.
By using sealants with low thermal resistance, such as those in our duct sealing systems, you ensure that cables remain in non-adiabatic conditions, where heat dissipation is optimised.
This is a critical consideration on water industry assets, where power, control and instrumentation cables are essential to keeping sites operational during and after an incident.
AMP8 Is About Getting the Details Right
Duct sealing may appear as a small detail on a drawing, but in reality, it plays a critical role in fire safety, gas protection and long-term asset resilience.
With DuctSeal FR, the water industry has access to a fully tested, British-made, WIMES-aligned fire-resistant duct sealing system that does exactly what the WIMES guidance intended.
Helpful Links
Explore further guidance, products and technical insights related to AMP8 and duct sealing systems: