1. NBR (Nitrile Butadiene Rubber, Standard Seal)
Temperature range: -30℃ to +80℃, up to 100℃ for short-term operation.
Pressure resistance: Suitable for low-pressure return lines (≤2.5 MPa) and medium-pressure pipelines (≤16 MPa). It features good elasticity and reliable sealing performance.
Compatible media: Mineral hydraulic oil, anti-wear oil and gear oil. Not resistant to phosphate ester and high-temperature water-based fluids.
Application: Standard return and suction filter elements for general industrial equipment and construction machinery. It is cost-effective and highly versatile. It tends to age and harden when oil temperature exceeds 80℃.
2. FKM (Fluoroelastomer, High-temperature & High-pressure Seal)
Temperature range: -20℃ to +120℃, with short-time resistance up to 150℃.
Pressure resistance: Designed for high-pressure pipelines (21–42 MPa) and servo systems. It withstands high-pressure impact and resists deformation.
Compatible media: Compatible with mineral oil, synthetic oil, ester oil and fire-resistant fluid. It boasts excellent aging resistance and chemical corrosion resistance. Being zinc-free, it works well with environmentally friendly media.
Application: Preferred for high-pressure circuits in metallurgy, wind power and machine tools, and is a must for operating temperatures above 80℃. It costs more than NBR, while its service life is extended by 30%–50%.
3. EPDM (Ethylene Propylene Diene Monomer, Fire-resistant & Water-based Special Seal)
Temperature range: -40℃ to +100℃ with outstanding low-temperature resistance.
Pressure resistance: Applicable to medium and low pressure (≤16 MPa), and resistant to swelling in water-based media.
Compatible media: Phosphate ester fire-resistant oil, water-glycol fluid and emulsions (HFA/HFC). Not for use with mineral oil, as it will swell severely and fail.
Application: The first choice for fire-resistant hydraulic systems and water-based working conditions in power plants and steel mills. Adopting zinc-free design to prevent clogging caused by zinc soap.
4. PTFE (Polytetrafluoroethylene, Extreme Corrosion & Ultra-high Temperature)
Temperature range: -60℃ to +200℃, capable of enduring extreme temperature differences.
Pressure resistance: Suitable for high pressure (≤42 MPa) with high mechanical strength and deformation resistance.
Compatible media: Strong acid, strong alkali, organic solvents and high-water-content fluids. It is chemically inert and will not react with any media.
Application: Used in chemical, marine and other working conditions with ultra-high temperature or severe corrosion. It has poor elasticity and requires metal reinforcement. It has the highest cost among the four materials.
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