Why MEKO Shouldn’t Be Used in Duct Sealants | DuctSeal UK Guide

Why MEKO Shouldn’t Be Used in Duct Sealants | DuctSeal UK Guide

Why MEKO Should Not Be Used in Duct Sealants

When specifying a cable seal system for cable ducts in industrial environments such as electrical substations or Ex zones, safety and performance are everything. One chemical you should avoid is MEKO. Using MEKO in a duct sealing system can pose unnecessary risks to both people and assets. This article explains why MEKO should not be used in duct sealants, drawing on scientific studies and compliance reports, and outlines why DuctSeal provides a safe, MEKO-free alternative.

What Is MEKO & Where Does It Appear in Sealants?

MEKO (Methyl Ethyl Ketoxime or 2-butanone oxime) is sometimes added to sealing compounds, adhesives, and coatings to prevent surface “skinning” and extend shelf life. In duct sealing systems or cable sealing kits, it can appear in certain mastic formulations or curing agents.

However, multiple regulatory authorities — including the EU’s REACH program and Australia’s National Industrial Chemicals Notification and Assessment Scheme (NICNAS) — have warned that MEKO is toxic and potentially carcinogenic. For applications involving pipes contained in walls, raceway seals, or cable scenarios that require re-entry or flexible sealing, you need a sealing system that is chemical agents resistant, odourless, and safe to apply.

Why MEKO Is a Risk for Duct Sealing Applications

1. Carcinogenic Classification

MEKO has been classified as a Category 1B carcinogen under EU CLP Regulation (Regulation (EC) No 1272/2008). Studies from OEHHA and NICNAS link prolonged exposure to liver toxicity and tumour formation in laboratory animals. The compound releases volatile organic compounds (VOCs) during curing, creating exposure risks for installers in confined areas such as basements, tunnels, or substations.

2. Off-Gassing & Worker Exposure

During curing, MEKO off-gasses into the surrounding air. In enclosed spaces with limited ventilation, this can be hazardous to anyone installing or maintaining the seal. For sealing ducts, bore holes, or pipes in electrical environments, a chemical agents resistant compound that is neutral and low odour is a far safer choice.

3. Environmental & Compliance Issues

According to sources such as Stop Carcinogens at Work and Borchers, regulatory action is ramping up across Europe and the UK. Manufacturers are being urged to phase out MEKO entirely by 2030. Any duct sealing system that contains MEKO could soon fall out of compliance, particularly for projects where safety and chemical resistance must align with international standards.

How MEKO Impacts a Cable Duct Sealing Scenario

When sealing cable ducts or ducts with several cables or one duct carrying multiple pipes, the sealing compound plays a crucial role. If the compound contains MEKO, it can compromise the seal’s chemical integrity and cause long-term deterioration. It may also reduce adhesion under humidity or alkaline conditions, leading to water ingress or even gas leaks in pressurised zones.

For example, in electrical installations that must comply with ATEX or IECEx standards, or those requiring re-entry to remove cables and modify seals, using a MEKO-based adhesive introduces unnecessary risk. A MEKO-free duct sealing system is suitable for these environments, providing complete separation and maintaining structural integrity even when installed retrospectively.

Specifying the Right MEKO-Free Duct Sealing Kit

When selecting a duct sealing product, make sure it meets the following:

  • MEKO-free, odourless, and neutral curing

  • High chemical resistance to oils, diesel, and alkaline conditions

  • Re-enterable and flexible for maintenance or cable transitions

  • Weather-resistant and suitable for Ex zones

  • Tested for fire performance, ensuring integrity under heat

The DuctSeal LG and DuctSeal HG systems are both MEKO-free and designed for long-term durability. Each kit comes with a sealing compound and backing material for simple, strong, and safe installation in accordance with UK and EU regulations.

Health and Safety Documentation

All DuctSeal products comply with the latest UK REACH and CLP guidelines. Our compounds are tested to resist moisture, gas, and chemical exposure, ensuring a stable and safe working environment for installers.

Conclusion: Choose MEKO-Free for Safety and Longevity

In short, MEKO has no place in modern duct sealing. Whether you’re sealing cables in substations, managing cable duct installations for utility tunnels, or working in confined industrial spaces, a MEKO-free solution delivers better safety, compliance, and performance.

Explore our full range of duct sealing systems or contact us for more info on our MEKO-free sealing kits designed to protect your installation, your team, and your long-term project integrity.

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