NBR O-Ring Seals CS 3.55/5/5.3mm ID 17–240mm Nitrile Gasket

NBR Nitrile Rubber O-Ring Seals — Versatile Mechanical Sealing Rings

Keep your machinery, plumbing, and equipment leak-free with these high-quality NBR (Nitrile Butadiene Rubber) O-Ring Seals. Available in cross-section diameters of 3.55mm, 5mm, and 5.3mm and inside diameters ranging from 17mm to 240mm, these gaskets cover an exceptionally wide range of industrial and household applications — from factory equipment and hydraulic systems to home plumbing and air conditioning units.

Made in Mainland China.

Key Features

• Material: Premium Nitrile Butadiene Rubber (NBR) — resistant to oils, fuels, and hydraulic fluids
• Cross-Section (CS): 3.55mm / 5mm / 5.3mm
• Inside Diameter (ID): 17mm – 240mm (wide selection)
• Shape: Standard ring gasket profile
• Oil Resistance: Excellent — ideal for oil-lubricated and hydraulic environments
• Wear Resistance: Durable construction handles repeated use and mechanical stress
• Waterproof: Creates a reliable liquid-tight seal
• Temperature Resistance: Performs dependably across a broad operating temperature range
• Standard dimensions — compatible with widely used industrial and domestic fittings
• Suitable for: Factories, workshops, air conditioning systems, and home plumbing

Why Choose NBR O-Rings?

Nitrile rubber is the industry-standard choice for sealing applications where oil, grease, water, or hydraulic fluid is present. Its excellent compression set resistance means the ring maintains its shape and sealing integrity over time, even under sustained mechanical pressure. Whether you're replacing worn-out seals in industrial machinery or fixing a leaky fitting at home, these O-rings deliver consistent, reliable performance.

Ideal Applications

• Hydraulic and pneumatic systems
• Air conditioning and refrigeration units
• Automotive and engine fittings
• Water pumps and plumbing connectors
• Industrial machinery and factory equipment
• General-purpose mechanical sealing

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Learn more: OSHA guidance on hand and power tools

Frequently Asked Questions

Q: What does "CS" and "ID" mean for NBR O-rings?

A: "CS" stands for Cross-Section diameter — this is the thickness of the rubber ring itself (3.55mm, 5mm, or 5.3mm in this listing). "ID" stands for Inside Diameter — the inner measurement of the ring that must match the groove or fitting it is sealing, ranging from 17mm to 240mm here. Selecting the correct CS and ID ensures a proper, leak-free seal.

Q: Are these O-rings suitable for use with oil and hydraulic fluid?

A: Yes. NBR (Nitrile Butadiene Rubber) is specifically formulated for excellent resistance to petroleum-based oils, hydraulic fluids, fuels, and greases, making these sealing rings highly suitable for hydraulic systems, automotive applications, and oil-lubricated machinery.

Q: Can I use these NBR O-rings for air conditioning or water applications?

A: Absolutely. These O-rings feature strong waterproof sealing characteristics and are listed as compatible with air conditioning systems. They work well in water pump connections, plumbing fittings, and refrigeration systems within their rated temperature range.

Q: How do I choose the right size O-ring for my application?

A: Measure the groove or fitting where the seal will sit. You need the Inside Diameter (ID) to match the shaft or bore size, and the Cross-Section (CS) to fit snugly in the groove depth. Refer to the standard O-ring size chart for your application and select the closest matching CS and ID from the available options in this listing.

Production & Packaging Notice

To maintain high stock availability and fast shipping times, our items are sourced from multiple verified manufacturing facilities. While the core quality, materials, and product specifications remain identical, you may notice slight variations in the packaging design, manufacturing origin, or the wording of the printed instructions.