Seals for All Working Conditions - NBR/PU/FKM In Stock

In hydraulic and pneumatic systems, the U-seal is one of the most widely used and critical dynamic sealing components. Its unique U-shaped cross-section allows the lips to make controlled contact with the mating surface, achieving low-pressure activation and pressure-enhanced sealing during reciprocating motion. However, no single material can perform optimally across all working conditions—oil temperature, pressure, media type, speed, and contamination levels all vary significantly. That is why maintaining in-stock availability of U-seals in three mainstream materials—NBR, PU, and FKM—enables us to offer application-matched solutions with immediate delivery.

1. NBR – Cost-Effective, Oil-Resistant, Universally Applicable

NBR (nitrile rubber) is the most common sealing material for hydraulic oil and mineral-based greases.

· Temperature Range: –30 °C to +100 °C

· Hardness: Shore A 70–90

· Advantages: Excellent resistance to mineral oils, good abrasion and tear strength, low material cost

· Typical Applications: Medium-to-low pressure hydraulic cylinders, pneumatic valves, repair kits for construction machinery

· Regional Search Trends: India, Turkey, Brazil (per Sheet2: while "PU" sees 617.7K monthly searches in India, NBR remains dominant in aftermarket and volume-driven sectors across developing economies)

2. PU – The Wear Champion for High-Frequency Reciprocation

Polyurethane U-seals are specified where mechanical strength and abrasion resistance are paramount—especially in contaminated environments containing sand, dust, or metal fines.

· Temperature Range: –20 °C to +80 °C (special grades up to +100 °C)

· Hardness: Shore A 90 to Shore D 55

· Advantages: High extrusion resistance, capability >40 MPa, exceptional resistance to abrasive wear

· Typical Applications: Breaker pistons, mining hydraulic supports, injection molding machines

· Material Search Insights: PU (617.7K monthly searches, India); TPU (171.6K, USA); PPDI (3.1K, Indonesia). PPDI‑type polyurethane is rapidly emerging as the preferred material for water‑based fluids and high‑frequency shock loads.

3. FKM – High Temperature and Chemical Resistance for Extended Life

FKM (fluoroelastomer) represents the ultimate barrier in severe service conditions.

· Temperature Range: –20 °C to +200 °C

· Hardness: Shore A 75–90

· Advantages: Exceptional heat resistance, broad chemical compatibility (acids, alkalis, ester-based fluids), low extractables

· Typical Applications: Steel mill equipment, engines, chemical pumps, food-grade hydraulic systems

· Regional Search Trends: USA, Germany (concentrated demand for high-temperature hydraulic sealing)

In-Stock Readiness:

We maintain inventory of U-seals conforming to ISO 5597, DIN 3771, and popular cross-section widths (3.0, 4.0, 5.0, 6.0, 7.5, 10.0 mm). Custom sizes are available with short lead times. Critically, NBR, PU, and FKM variants are fully interchangeable within the same groove dimensions—no housing redesign required. Sample shipments within 24 hours; production quantities in 3 days.

Conclusion:

Stop compromising service life with a "one‑material‑fits‑all" approach, and stop paying for premium materials where they aren't needed. Select U‑seals by operating condition—we have the stock to prove it.