The Ultimate Guide To NBR Rubber Foam Tube: Properties, Applications, And Benefits

In the world of industrial insulation and sealing, few materials offer the versatility and robustness of NBR rubber foam tube. Whether you are in the HVAC industry, automotive manufacturing, or marine engineering, understanding this closed-cell elastomeric material can significantly impact the efficiency and longevity of your projects.

At CONING Insulation, we specialize in high-quality extruded NBR foam tubes. In this guide, we’ll dive deep into what NBR foam is, its key properties, diverse applications, and why it outperforms other materials.

NBR (Nitrile Butadiene Rubber) foam tube, often referred to as nitrile foam, is a synthetic rubber material engineered into a flexible, closed-cell structure. It is typically produced through an extrusion process where the compound is mixed with foaming agents and cured under high heat.

The result is a lightweight, tube-shaped foam with a smooth or skin-like surface. Unlike open-cell foams, the closed cells in NBR foam are sealed, preventing the passage of air, water, and moisture.

Key Properties and Advantages

Why do engineers specify NBR foam over other elastomers? The answer lies in its unique chemical and physical composition.

1. Superior Oil and Fuel Resistance

NBR is the material of choice when resistance to oils, fuels, and greases is required. This makes NBR foam tubes indispensable in automotive and industrial settings where contact with petroleum-based substances is daily.

2. Closed-Cell Structure for Moisture Barrier

Because it is closed-cell, NBR foam acts as an excellent vapor barrier. It features a very low water absorption rate (as low as 0.1% by volume) and a high water vapor diffusion factor, which prevents condensation and corrosion under the insulation

3. Thermal and Acoustic Insulation

With thermal conductivity as low as λ = 0.034 W/mK, NBR foam tubes are highly efficient for energy conservation in HVAC systems. Additionally, its density helps dampen vibrations and reduce noise transmission in machinery and piping

4. Wide Temperature Tolerance

Standard NBR foam performs reliably across a broad temperature range, typically from -40°C to +105°C (or up to +110°C in specific tube formats), making it suitable for both refrigeration lines and hot water pipes

5. Environmental and Safety Compliance

Modern NBR foams are manufactured to be environmentally friendly. They are often CFC and HCFC-free, have zero Ozone Depletion Potential (ODP) , and very low Global Warming Potential (GWP) . Many grades also meet strict fire safety standards

NBR vs. EPDM vs. EVA: What’s the Difference?

When selecting a foam tube, it’s important to distinguish between common materials:

• NBR (Nitrile): Best for oil and fuel resistance. Ideal for automotive and industrial applications.

• EPDM: Excellent for weather resistance and UV exposure. Often used for outdoor sealing, but swells in contact with oils.

• EVA: A plastic foam often used for sports mats and crafts. Unlike extruded NBR, EVA tubes are usually made by drilling a solid block, meaning the inner hole is not skin-sealed like the rubber version