Rubber Seal Material Selection Guide: Comparison Of NBR, EPDM And Silicone

Rubber seal material selection guide: comparison of NBR, EPDM and silicone

In a variety of sectors, rubber seals help to prevent liquid and gas leaks while also protecting equipment from the outside environment. When selecting the appropriate rubber material, consider how varied use situations, working temperatures, chemical media, and so on will affect the material's performance. Common rubber seal materials include NBR (nitrile rubber), EPDM (ethylene propylene diene monomer rubber), and silicone (VMQ), each with its own set of advantages. Understanding their characteristics will help you make a better decision.

1. NBR (nitrile rubber)

Nitrile rubber (NBR) is a synthetic rubber that is predominantly copolymerized with butadiene and acrylonitrile. It has strong oil resistance, wear resistance, and elasticity, thus it is widely utilized in a variety of industrial applications.

Oil resistance and chemical resistance

The most notable attribute of NBR is its superior oil resistance, particularly for mineral oil and fuel. It has high tolerance. NBR is commonly used in seals in the automotive, petrochemical, and industrial industries. NBR has a low tolerance for various organic solvents and chemicals, and it will break and weaken in strong acidic and alkaline environments.

Temperature resistance

NBR has a limited operating temperature range and is typically acceptable for conditions ranging from -40 °C to +120 °C. Under high temperature conditions, NBR performance steadily degrades, and prolonged exposure to high temperature environments causes the material to harden and lose elasticity. It is not recommended for use in industries with high-temperature environments or steam.

Wear resistance and mechanical properties

NBR has a high wear resistance and is ideal for sealing mechanical friction parts like sealing rings in hydraulic systems. It has a high hardness and can withstand a specific level of mechanical pressure, thus it is commonly used in vehicle engine seals, hydraulic systems, and other applications.

Application areas

• Automotive industry: such as oil seals, fuel pipe seals.
• Petrochemicals: such as sealing of hydraulic oil, lubricating oil and other oils.
• Mechanical engineering: used for sealing of hydraulic and pneumatic systems.

2. EPDM (ethylene propylene diene monomer rubber)

EPDM (ethylene propylene diene monomer rubber) is a synthetic rubber with superior weather, age, and ozone resistance. EPDM has a distinct molecular structure and can withstand extreme conditions.

Chemical resistance

EPDM has excellent chemical resistance, particularly against acids, alkalis, oxidants, and water. It resists more chemicals than NBR. EPDM works very well in steam, hot water, and humid situations. However, EPDM has a low tolerance for oils, solvents, and petroleum-based chemicals.

Temperature resistance

EPDM has a wide temperature resistance range, allowing it to adapt to temperatures ranging from -40 °C to 150 °C. EPDM can maintain acceptable physical characteristics and flexibility in high-temperature settings, making it appropriate for sealing at these temperatures.

Weather resistance and aging resistance

EPDM has exceptional oxidation and ozone resistance, can withstand ultraviolet radiation and climatic change, and is suited for outdoor use and sunshine exposure. EPDM is ideal for automobile sealing strips, roofing materials, and other applications in tough conditions.

Application areas

• Automotive industry: used for door seals, window seals, tire seals, etc.
• Construction industry: used for roof waterproofing, window sealing strips, etc.
• Food and pharmaceutical industry: used for sealing of water treatment, hot water pipes and steam systems.

3. Silicone (VMQ)

Silicone (VMQ) is a siloxane-based synthetic rubber that is highly temperature resistant and biocompatible. Silicone is frequently employed in a variety of high-end sectors due to its excellent flexibility and electrical insulating qualities.

Temperature resistance

Silicone can tolerate temperatures ranging from -60 °C to +230 °C. Silicone can maintain its suppleness and flexibility even at high temperatures. Silicone is a splendid choice for high-temperature, dry, or steam situations.

Chemical resistance

Silicone has a low tolerance for most chemicals, acids, alkalis, oils, and solvents, yet it is highly resistant to water and oxygen. Silicone, which is resistant to chemical corrosion, is widely used in the medical and food industries for parts that come into contact with food or medicine, such as food processing equipment, pharmaceutical seals, and so on.

Electrical insulation properties and biocompatibility

Silicone has splendid electrical insulating qualities and is commonly utilized in the electrical and electronic sectors. Silicone has exceptional biocompatibility and is frequently utilized in medical equipment, infant items, and other applications.

Weather resistance and aging resistance

Silicone is weather resistant and can withstand UV radiation and oxidation, making it ideal for outdoor or exposed applications. Silicone seals' chemical stability allows them to be utilized in severe conditions for extended periods of time.

Application areas

• Medical industry: used for sealing medical devices, catheters, and surgical instruments.
• Food industry: used for sealing food processing equipment and drinking water systems.
• Electronics industry: used for waterproof and dustproof sealing of electronic equipment.
• Automotive industry: used for engine sealing, lamp sealing, etc.

4. Comparison summary of NBR, EPDM and silicone