AN6226-04 Buna-N 70 U-Cup Seal 5/16" ID X 11/16" OD X 3/16" CS

Get consistent sealing and smooth performance in your hydraulic or pneumatic system with the AN6226-04 U-Cup Seal. Built to reduce leaks and downtime, this seal helps keep your equipment running efficiently without unnecessary maintenance.

Made from black Buna-N (NBR) at 70 durometer, this U-Cup delivers excellent oil resistance and flexibility. It is a dependable solution for customers who need reliable sealing in compact applications where performance and fit matter.

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

Material & Performance Details

This seal is manufactured 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 for sealing and durability for long service life.

U-Cup seals energize under pressure and do not require heavy initial compression, making them ideal for low breakaway pressure and smooth operation.

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 weather exposure

Not compatible with:

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

Sizes & Measurements

• Cross Section (CS): 3/16" (0.187" | 4.75 mm)
• Inside Diameter (ID): 5/16" (0.312" | 7.94 mm)
• Outside Diameter (OD): 11/16" (0.687" | 17.46 mm)
• Part Number: AN6226-04
• Cross References:
  • Parker Hannifin: 42956226-04
  • Hercules: 870-04
  • Martin Fluid Power: 6226-04
  • Precision Associates: 6226-4

Dimensions: 5/16" ID X 11/16" OD X 3/16" CS
Actual: 0.312" ID X 0.687" OD X 0.187" CS
Metric: 7.94 mm ID X 17.46 mm OD X 4.75 mm CS

Applications & Use Cases

This AN6226 Series U-Cup is commonly used in hydraulic cylinders, pneumatic systems, pumps, and valves. It is well suited for applications that require reliable sealing with low friction and consistent performance.

Rated for pressures up to 500 PSI, it is a dependable choice for both OEM 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 reliability, speed, and support that helps you get it right the first time.

• 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 avoid downtime and keep your operation moving.

FAQs

1. What does AN6226 mean?
AN6226 is an Army-Navy standard that defines U-Cup seal sizes and ensures interchangeability.

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.