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What Duct Sealing System Should I Use?

What Duct Sealing System Should I Use?


Selecting the appropriate duct sealing system is a crucial decision, and with the diverse range of technologies available, finding the right fit can be challenging. At AC Cable Solutions, we understand the importance of tailoring solutions to specific needs. In this guide, we'll walk you through the considerations that will help you make an informed decision.

Or you can just give us a call, and we’ll offer the best solution for your project. Call 0161 806 1666 or email 

Before delving into the technical details, consider the following fundamental factors:

The basics first

  • Inner Diameter (I/D): Measure the inner diameter of the duct.
  • Orientation: Is the duct positioned vertically or horizontally.
  • Number of Cables/Pipes: Determine the quantity within the duct.
  • Overall, Cable Diameter (O/D): Essential for mechanical seals, useful for all systems.
  • Duct Condition: Assess whether the duct is dry or has running water.

These basics lay the foundation for a well-informed choice in duct sealing systems.

Diving Deeper:

For a more nuanced decision, explore the following technical aspects:

  1. Performance Requirements:
  • Pressure Rating: Identify the required pressure handling capabilities.
  • Flame Retardance: Determine if flame retardant properties are necessary.
  • Fire Resistance: Assess the need for resistance to fire.
  • LSOH: Is a Low Smoke or Zero Halogen product required, or even both?
  • Non-Hazardous: Do you want to protect your users or installers when installing a chemical or compound seal.
  • Do you need to backfill straight away if sealing externally
  1. Specialised Resistances:
  • Chemical or Corrosive Gas Resistance: Consider resistance to gases like hydrogen sulphide, methane, or chlorine.
  • Hydrocarbon Resistance: Evaluate resistance to substances such as petrol, diesel, or ethanol.
  • Protection Against Rodents: Determine if the system needs to withstand rodent interference.
  • Antimicrobial Properties: Consider resistance to bacteria or fungi.
  1. Installation and Maintenance:
  • Cable Density: Assess whether the duct is filled with cables.
  • Future Access Needs: Determine if re-entry into the duct is necessary and how often.
  • Installation: Do you have your own team of engineers, or do you need to find an installation team.
  1. Compliance with Standards:

Industry Standards: Check if compliance with specific standards is required.

Let's delve into the specifics and guide you in choosing the optimal duct sealing system based on your basic information:

  1. Dry Ducts with No Running Water: Cables below 25mm

In scenarios where both the duct and cables remain dry, or can be easily dried with no presence of running water, the optimal choice for a sealing system is Duct Seal LG⬅️ Click the Link 

Duct Seal LG is a reliable solution designed to withstand up to 1 Bar of water, gas, and air pressure. It is primarily used when dealing with cables, each with a diameter smaller than 25mm.

  1. Dry Ducts with Cables Above 25mm, Allowing Movement:

For ducts featuring cables with a diameter exceeding 25mm that can be manoeuvred to create a minimum 10mm gap between each cable and the duct's interior, the recommended sealing system is Duct Seal HG⬅️ Click the Link 

Duct Seal HG provides enhanced durability, offering up to 2 Bar resistance to water, gas, and air pressure. It is specifically designed to separate & support larger cables. The circular backing tubes can be interconnected to form a cross-piece for trefoil/triplex cables or a collar for quickly supporting single cables or pipes. The circular tubes can also be joined in groups of 5, split, compressed, or used as a whole unit to achieve a strong support around singular or multiple cables.

  1. Presence of Running Water or Immediate Backfilling Needs:

In instances where either of the previously mentioned conditions applies, but running water is present, or immediate backfilling is necessary—especially in external sealing scenarios—the ideal choices are the Kraso Universal Mechanical Sealing System or the Kraso SD Customised Mechanical Sealing System.

Kraso Universal Seal ⬅️ Click the Link 

The Kraso Universal Seal is a versatile off-the-shelf solution that accommodates various duct sizes and cable configurations. It's designed to handle the most common duct sealing requirements encountered on-site. Each of the cable entries has peelable layers to accommodate the cable O/D.

Kraso SD Customised⬅️ Click the Link 

For those unique site conditions, our SD Sealing System can be tailored to match your specific cable and site requirements.

How the Kraso Sealing systems work:

The Kraso sealing system features robust stainless-steel plates sandwiching a resilient EPDM rubber core. The magic happens with our patented self-torque-rated nut, which gently compresses the rubber. This compression causes the rubber to expand, forming a gas & watertight seal around your cables and the inner surface of the duct. The nut cannot be over-tightened; it clicks and spins around loosely when at the correct tightness.

Special Note for Scenario No.1:

In cases where cables are above 25mm and the duct is vertical, Duct Seal LG is also a suitable choice. In vertical scenarios, even with large and heavy cables, there is minimal weight on the backing system, ensuring effective sealing.

Having covered the fundamentals, let's now explore the specific resistances and compliance aspects, a straightforward task when utilising Duct Sealing systems from AC Cable Solutions. Our comprehensive range ensures the following resistances:

  1. Corrosive Gas Resistances:

Resistance here signifies that the material remains robust, with no degradation when exposed to these toxic corrosive gases. In simpler terms, our seals retain their strength even with prolonged exposure. For a more detailed understanding, feel free to request our test report.

  1. Hydrocarbon Resistances:
  • Petrol Resistance
  • Diesel Resistance
  • Ethanol Resistance
  • AdBlue Resistance
  • ASTM Oil
  • HVO Synthetic Diesel Resistance
  • LPG Gas

Similarly, resistance in this context assures that our material remains intact when in contact with various hydrocarbons. The strength of our seals endures, offering reliability even with prolonged exposure to these hydrocarbons. For a comprehensive insight, we invite you to inquire about our test report.

Understanding the durability and reliability of our sealing systems is not just a claim; it's a testament supported by thorough testing. We believe in transparency, and our test reports serve as a testament to the resilience of our materials against corrosive gases and hydrocarbons. If you have any questions or need further clarification, please do not hesitate to reach out for a detailed examination of our test reports. Your peace of mind is our priority.

Every Duct Sealing System manufactured or provided by AC Cable Solutions demonstrates resistance to all the toxic gases and hydrocarbons mentioned earlier. Below is a snapshot highlighting the features of our three most popular seals, showcasing the exceptional capabilities of each:


Keep it simple: 

  • For DRY ducts with cables less than 25mm O/D - Duct Seal LG ⬅️ Click the Link 
  • For DRY ducts with cables larger than 25mm O/D - Duct Seal HG ⬅️ Click the Link 

Note: Duct Seal HG handles both small and large cables, making it a convenient single-system choice for DRY ducts of all sizes.


In the intricate world of duct sealing, the key to success lies in gathering fundamental information tailored to your specific needs. By understanding the basics, you pave the way for informed decisions, ensuring that the chosen sealing system aligns seamlessly with your unique requirements.

Choosing AC Cable Solutions as your trusted supply partner for duct sealing opens the door to a comprehensive and hassle-free experience. Our diverse range of sealing systems caters to a spectrum of conditions, from dry ducts to those with running water, and from smaller cables to larger, more complex configurations.

With a commitment to excellence, our seals resist corrosive gases and hydrocarbons, providing a robust defense against environmental challenges. The transparency of our testing reports reinforces the reliability of our products, assuring you of their performance under various conditions.

In partnering with AC Cable Solutions, you gain more than a supplier — you gain a one-stop solution for all your duct sealing requirements. From basic considerations to specialised resistances and compliance needs, our offerings are designed to meet the diverse demands of your projects.

Ongoing Expansion:
This blog is a dynamic space that will continue to evolve as we introduce new insights and information. We encourage you to revisit periodically to witness its continuous growth and stay updated on the latest additions.

Written by Carl Pike - The Duct Sealing Man 

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