dbde24e1-4012-47b6-8db4-e89ee4ca5a70 - Polypac

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Polypac U-Cup Seal — Reliable Hydraulic U-Cup Sealing Solutions

Polypac U-Cup seals deliver low-friction, high-performance sealing for hydraulic systems. Available in multiple elastomers and custom sizes, they reduce leakage, extend service life and suit harsh conditions.

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Product Description

Product Overview

Polypac U-Cup Seal is a dependable hydraulic sealing solution designed for piston and rod applications. The U-shaped lip provides a secure dynamic seal with minimal friction, making it ideal for reciprocating and light rotary movements. Backed by Polypac’s 15+ years of sealing expertise and advanced manufacturing, our U-Cup seals offer consistent performance across a wide range of working conditions.

Key Features

U-shaped profile for effective pressure-energized sealing
Low friction for smooth motion and reduced wear
Available in NBR, FKM, EPDM, silicone, FFKM and PTFE-filled compounds
Wide temperature and chemical compatibility depending on material
Custom sizes and tolerances to fit special applications

Benefits for Your System

Using Polypac U-Cup seals reduces leakage and maintenance downtime, improves hydraulic efficiency, and extends component life. The flexible U-lip adapts under pressure, ensuring a tight seal even with shaft misalignment or rapid pressure changes. Selecting the right material helps resist oils, fuels, and common hydraulic fluids for reliable field performance.

Materials & Customization

We offer standard elastomers (NBR, FKM, EPDM, silicone) and high-performance options like FFKM and various filled PTFE compounds. Polypac’s in-house material development and large production facility allow fast prototyping and custom molding to meet special temperature, pressure, or chemical resistance requirements.

Why Choose Polypac

Polypac is a scientific and technical hydraulic seal manufacturer with a 10,000+ m² facility and advanced production and testing equipment. Since 2008 we’ve worked closely with universities and research institutions to deliver reliable seal solutions. Our long-term focus on quality, material R&D, and customized service makes us a trusted partner for OEMs and maintenance teams.

Applications

Hydraulic cylinders, mobile machinery, industrial presses, pneumatic systems, and any equipment requiring reliable dynamic sealing.

Contact Polypac to specify material, size, and tolerances for your U-Cup seal needs and ensure the best match for your operating environment.

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Q&A

Can I reuse a seal?

We strongly recommend never reusing seals. Once compressed and used, a seal takes a "set" and its elastic properties are degraded. Reusing it almost always results in a leak. Always install a new seal during any maintenance or repair.

How can I prevent seal damage during installation?

Use Tools: Always use dedicated installation tools (e.g., picks, cones, guides). Lubricate: Always lubricate the seal and the contact surface. Protect Sharp Edges: Cover sharp threads and edges with tape or use an installation sleeve. Check the Groove: Ensure the installation groove is clean, deburred, and undamaged.

What does "AS568" mean?

AS568 is the Aerospace Standard that defines the dimensions for over 360 standard O-ring sizes. It is the most widely accepted sizing system in North America and globally. An AS568 number (e.g., AS568-214) specifies a precise inside diameter and cross-section.

Why did my O-ring fail prematurely?

Common causes of O-ring failure include: Chemical Incompatibility: Swelling, softening, or cracking due to fluid exposure. Improper Sizing: Using an incorrect size leads to over-compression or inadequate sealing force. Abrasion: Wear and tear from rough surface finishes or contaminated fluid. Extrusion: The seal is forced into the gap between metal parts under high pressure. Installation Damage: Nicks, cuts, or twists during assembly.

Let's talk

PRODUCTS

dbde24e1-4012-47b6-8db4-e89ee4ca5a70

Polypac Industrial Technology Co.,Ltd

+86 189 2463 6168

rose@dmsseals.com

No. 5, Hegui Mid Road, Hegui Industrial Park, Lishui Town, Nanhai District, Foshan City, Guangdong Province, P.R. China.

URD Series U-Cup Seal | High-Pressure & Anti-Extrusion Rod Seal

Polypac’s URD Series U-Cup Seal offers heavy-duty, high-pressure performance with superior anti-extrusion protection. Crafted from durable urethane, this rod seal ensures long-lasting reliability in demanding applications. Ideal for efficient sealing in hydraulic systems.

URD Series U-Cup Seal | High-Pressure & Anti-Extrusion Rod Seal