Comprehensive Technical Specifications: EPDM & HNBR Rubber Materials

As an important member of the rubber-elastic sealing butterfly valve family, the Concentric Butterfly Valve features a simple structure and convenient maintenance and replacement, making it widely used in water treatment, petrochemicals, fire protection, and other fields. The concentric butterfly valve primarily consists of components such as the valve body, disc, seat, and shaft, with the disc and seat being the main parts in contact with the medium. Therefore, the selection of their materials is particularly critical. Especially for the rubber seat, as a synthetic polymer, the stability of its characteristics directly affects the quality of the finished valve.

The sealing materials for concentric butterfly valves are generally rubber or fluorine, primarily used under pressures up to 25 Bar. Butterfly Valve Seats are mainly categorized into hard-backed replaceable rubber seats, backless replaceable seats, and vulcanized non-replaceable seats. The choice between replaceable and non-replaceable seats primarily depends on pressure and application conditions.

Figure 1: Finished product warehouse of rubber valve seat factory

Ethylene Propylene Diene Monomer (EPDM) Overview

EPDM rubber is recognized for its excellent resistance to oxidation, ozone, erosion, and aging, making it widely applicable in various environments including water, seawater, alcohol, liquefied organic salts, and mineral acid/alkaline solutions.

According to formula adjustments, it can be used for higher temperature water or drinking water.

Figure 2: Replaceable valve seat with backrest

Enhanced EPDM Formulations

Driven by practical demands, formula refinements have led to specialized variants:

Nitrile Rubber (NBR) & Hydrogenated Nitrile Rubber (HNBR)

Nitrile rubber is primarily valued for its oil and wear resistance, commonly used in oil and gas applications, though with more limited temperature tolerance compared to EPDM.

Through selective hydrogenation modification, HNBR retains oil and wear resistance while significantly improving high and low-temperature capabilities, gaining certain acid and alkali resistance.

HNBR-seated butterfly valves leverage the excellent performance of HNBR rubber seats, making them well-suited for applications in petroleum and grease industries, particularly in both low and high-temperature environments.

Other Rubber Materials in Valve Applications

Within the rubber family, materials like Fluorocarbon Rubber (FKM) and Silicone Rubber (VMQ/SI) also play important roles, particularly in steam or food-related applications, though their temperature performance is generally not superior to HNBR.

As a core component of concentric resilient-seat butterfly valves, the selection of valve seat material is crucial to performance, longevity, and application suitability.