Application and Selection Guide of EPDM and NBR Sealing Materials in Non-Rising Stem Gate Valves

In industrial pipelines, non-rising stem gate valves are widely used in fluid control systems, and their sealing performance is crucial. The choice of sealing material directly affects the valve's sealing effect, durability, and adaptability. EPDM (Ethylene Propylene Diene Monomer) and NBR (Nitrile Butadiene Rubber) are two commonly used sealing materials in non-rising stem gate valves, each with different properties and application scenarios. This article explores the applications of EPDM and NBR in non-rising stem gate valves and how to select the appropriate sealing material based on the working environment.

Basic Characteristics of EPDM and NBR

EPDM is a synthetic rubber known for its excellent resistance to weather, high temperature, and chemicals, such as ozone and oxidation. EPDM is particularly suitable for high-temperature, high-humidity, or harsh environmental applications. Its working temperature can typically reach up to 120°C, making it ideal for various industrial uses, including chemical, pharmaceutical, and water treatment industries.

NBR, on the other hand, is widely used for its excellent oil resistance and wear resistance in fluid transmission and mechanical sealing applications. NBR’s temperature range is generally between -40°C to 80°C, making it a common choice in the petroleum and automotive industries, where oil, fat, and petroleum products are involved. NBR materials also offer good elasticity and aging resistance, making them ideal for low-temperature and oil-based environments.

Selection Guide for EPDM and NBR

1. Working Temperature and Media Selection

   • If the working environment has higher temperatures, or if the valve is primarily used in water treatment or steam pipelines, EPDM is the better choice. It can withstand temperatures up to 120°C and performs well in various aqueous liquids and chemicals.

   • If the valve is used in oil-based or fat-containing environments, such as in petrochemical or lubrication systems, NBR is the preferred choice. It has superior oil resistance and can effectively prevent aging when exposed to oil-based media.

2. Chemical Resistance

   • In environments requiring resistance to strong acids or alkalis, EPDM’s chemical stability is superior, making it suitable for a wide range of chemical substances. NBR has lower resistance to certain chemicals.

   • For environments involving solvents or oils, NBR’s superior oil resistance ensures reliable sealing performance over time.

3. Sealing Performance and Durability

   • Due to EPDM’s excellent elasticity, it can maintain a long-lasting sealing effect under high pressure and high temperature, making it ideal for high-temperature and high-pressure applications.

   • NBR is more suitable for low-temperature and oil-based media, offering reliable sealing performance when in prolonged contact with oil and fats.

Conclusion

When selecting sealing materials for non-rising stem gate valves, both EPDM and NBR have their advantages and disadvantages. EPDM is best for high-temperature and water-based media, while NBR excels in oil and low-temperature environments. Understanding the specific working conditions and types of media will help you make an informed choice, ensuring long-term stable operation of your non-rising stem gate valve.