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What is the E-glass Used in Fire Sleeve?

April 8, 2024

National Firesleeve offers a range of protective sleeving to protect wires, cables and hydraulic hoses and pipes from high temperatures, and protect operators from burns from hot pipes, steam lines and conduits.

Fire Sleeve can deliver continuous protection in ambient operating temperatures of up to 260°C and resist molten splash up to 1200°C. This is achieved by the use of E-glass fibers coated in a high-grade silicone elastomer rubber.

But what is E-glass, how is it made and how does it make Fire Sleeve such a high-performance protector?

What is E-glass?

Electrical glass, better known as E-glass, was first developed in the 1930s as an electrical insulator – hence the name. However, it was soon found to have many other useful properties, including very low thermal conductivity. This makes it ideal for protecting wires, cables and pipes in high temperature situations.

E-glass is inorganic, incombustible and rot proof, and it is resistant to most common chemical agents. It’s also strong, with a higher tensile strength than steel. E-glass can be found in all kinds of sectors and products, from aerospace to construction, and even in the thermal seal around your oven door.

How is E-glass made?

The E-glass in Fire Sleeve is made from boron oxide, silicone oxide (silica), lime, aluminum oxide (alumina) and magnesium oxide (magnesia). This mixture is heated to 1500°C to create a clear molten mass, which is then passed through fine holes to form thin fibers.

These fibers are spun and then knitted together to form the inner layer of Fire Sleeve. This is coated with an outer layer of silicone elastomer rubber to enhance flexibility, protect the glass fibers from fraying and improve the thermal protection properties of the product.

Fully flexible Fire Sleeve production

The production process is fully adaptable, allowing National Firesleeve to create both standard and bespoke diameters of protective fire sleeves, from 4mm (0.16”) for individual cables, to 203mm (8”) for larger pipes and conduits.

Fire sleeves can also be produced in both standard and bespoke lengths to avoid waste and reduce installation costs. National Firesleeve is available a range of colors, including red oxide, blue, silver, black, yellow and bright red to help differentiate complex pipework and cable installations. We can also create Fire Sleeves in custom colors to match your specific requirements.

What are the properties of E-glass?

E-glass has low thermal conductivity, with a value in the range ~0.8 – 1.2Wm-1K-1. The allows Fire Sleeve to meet the requirements of UL94 – V0. This standard has been harmonized with a range of international standards, including IEC 60695-11-10 and 60695-11-20 and ISO 9772 and 9773.

Fire Sleeve is highly resistant to most oils, hydraulic fluids, acids and alkalis, with the rubber coating forming a protective silicone oxide layer when exposed to flame. It is also highly flexible, conforming well onto intricate insulations.

E-glass Fire Sleeve

Fire Sleeve is manufactured in Great Britain to the highest standards, and it is exported around the world to Europe, the Far East and the United States. It is used across a wide range of industries from heavy manufacturing to smelting, from mining machinery to marine engine rooms, from rail transport to offshore wind generation.

To find out more about how the exceptional protection levels of National Firesleeve can work for you and your industry, get in touch with our team today. With Fire Sleeve available in exactly the diameter, reel length and color required to meet your precise specifications, the answer is yes – now what’s the question?