AN6226-33 Buna-N 70 U-Cup Seal 2-1/4" ID X 2-7/8" OD X 5/16" CS

Get a heavy-duty, stable seal designed for larger bore applications where reliability is critical. The AN6226-33 U-Cup Seal delivers consistent sealing performance, helping prevent leaks, reduce downtime, and keep your hydraulic and pneumatic systems running efficiently.

Manufactured from black Buna-N (NBR) at 70 durometer, this U-Cup offers excellent oil resistance and durability. The 5/16" square profile provides added sealing strength and stability, making it a dependable choice for demanding fluid power applications.

Operating temperature: -40° to +225°F (–40° to +107°C)

Material & Performance Details

This seal is made from Buna-N (Nitrile, NBR), one of the most widely used sealing materials in fluid power systems. The 70 durometer hardness provides a strong balance between flexibility and long service life.

The AN6226 design features a square-style cross section where the nominal cross section equals the height, improving sealing stability and ensuring consistent performance under pressure.

Excellent resistance to:

• Petroleum-based oils and fuels
• Hydraulic fluids
• Mineral oils and greases
• Water (short-term exposure)

Limited capability with:

• Mild acids and bases
• Ozone and outdoor exposure

Not compatible with:

• Strong acids
• Brake fluids (glycol-based)
• Aromatic hydrocarbons

Sizes & Measurements

• Cross Section (CS): 5/16" (0.312" | 7.94 mm)
• Inside Diameter (ID): 2-1/4" (2.250" | 57.15 mm)
• Outside Diameter (OD): 2-7/8" (2.875" | 73.03 mm)
• Part Number: AN6226-33
• Cross References:
  • Parker Hannifin: 42956226-34
  • Hercules: 870-34
  • Martin Fluid Power: 6226-34
  • Precision Associates: 6226-33

Dimensions: 2-1/4" ID X 2-7/8" OD X 5/16" CS
Actual: 2.250" ID X 2.875" OD X 0.312" CS
Metric: 57.15 mm ID X 73.03 mm OD X 7.94 mm CS

Applications & Use Cases

This AN6226 Series U-Cup is commonly used in hydraulic cylinders, pneumatic systems, pumps, and valves where larger diameters and increased sealing strength are required. The larger cross section makes it well suited for applications with higher wear, wider tolerances, or heavier loads.

With a pressure rating up to 500 PSI, it is a dependable solution for both OEM equipment and maintenance applications.

Key Specifications

• Material: Buna-N (NBR)
• Durometer: 70 Shore A
• Color: Black
• Specification: AN6226 (Army-Navy Standard)
• Temperature Range: -40°F to +225°F (-40°C to +107°C)
• Pressure Rating: Up to 500 PSI

Why Buy from The O-Ring Store LLC

When you order from us, you are getting more than just a seal. You are getting accuracy, speed, and support that helps you avoid downtime and rework.

• ISO9001:2015 certified quality processes
• USA stock for fast delivery
• Same-day shipping on in-stock items
• Custom sizes available when standard sizes do not fit
• Full lot traceability and documentation available
• Technical support from experienced staff
• Competitive pricing without sacrificing quality

We focus on helping you get the right seal the first time so your equipment keeps running.

FAQs

1. What is the advantage of the 5/16" cross section?
The larger cross section provides increased sealing strength and stability, especially in applications with higher loads or wider clearances.

2. Is Buna-N suitable for hydraulic systems?
Yes. Buna-N offers excellent resistance to petroleum-based oils and hydraulic fluids.

3. What pressure can this seal handle?
This U-Cup is rated for applications up to 500 PSI.