Teflon PTFE Split Backup Ring AS568A-211 - 2774

Precision Support for High-Pressure O‑Ring Seals

A PTFE backup ring sized to AS568A-211 eliminates elastomer extrusion and extends seal life in high-pressure hydraulic and pneumatic glands, giving engineers fewer leaks, less downtime, and a sealing system they can trust at pressures exceeding 3,000 psi.

Why You'll Love It

Whether you are an engineer designing a new cylinder or a maintenance manager chasing recurring seal failure on legacy equipment, the PTFE backup ring AS568A-211 delivers measurable results across a wide range of demanding applications.

What Makes It Different

Most generic back up rings are manufactured to approximate dimensions with loose tolerances and unfinished edges. That means inconsistent gland fill, rough surfaces that nick the companion O ring, and premature seal failure under real-world operating pressure.

The PTFE backup ring AS568A-211 is built differently:

• Tight AS568A tolerances – CNC-machined or precision-molded to hold ID, OD, and cross-section within narrow bands, ensuring the extrusion gap is consistently blocked across production lots. The AS568 series is an O-ring size designation standard, and our rings are manufactured to match it exactly.

• Application-specific PTFE grades – Beyond virgin PTFE, we offer 15 % glass-filled, 25 % carbon-filled, and bronze-filled options. While backup rings can be made from materials like PEEK and Nylon, PTFE provides superior chemical inertness compared to rubber or nylon rings, making it suitable for aggressive media in chemical processing and aerospace.

• Optimized edge geometry – Every ring is chamfered and deburred so it protects the mating -211 O ring during installation and pressure cycling, reducing wear on the elastomer and extending service life.

How It Works

The PTFE backup ring sits adjacent to an AS568A-211 O ring inside the seal gland. Backup rings prevent O-rings from extruding under pressure - here is how:

1. Install the ring – Place the AS568A-211 PTFE backup ring in the groove on the low-pressure side of the -211 O ring. A PTFE backup ring can be solid, split, or spiral-cut for installation, so choose the style that suits your assembly constraints. If the gland sees bidirectional pressure, install two back up rings - one on each side.

2. Pressurize the system – When system pressure rises, the softer elastomer O ring energizes against the hardware surfaces to create a seal. The rigid PTFE anti extrusion ring blocks the clearance gap between mating parts, preventing the O ring from flowing into it.

3. Maintain reliable sealing – Under sustained or pulsating pressure - including pressure spikes - the PTFE ring absorbs the load on the downstream side. The elastomer O ring retains its shape, avoiding nibbling and feathering. PTFE maintains dimensional stability under extreme pressure cycling, so the seal stack continues to function correctly across thousands of cycles.

Product Details

Key specifications for the PTFE backup ring AS568A-211 at a glance:

• Material: PTFE (polytetrafluoroethylene). Options include virgin PTFE, 15 % glass-filled PTFE, and 25 % carbon-filled PTFE depending on duty requirements. PTFE is commonly used for backup rings due to low friction and outstanding chemical resistance.

• Standard size code: AS568A-211, matched to the standard -211 O ring cross-section and groove dimensions.

• Dimensions: Inside diameter ≈ 0.796 in (20.22 mm); cross-section ≈ 0.139 in (3.53 mm); outside diameter ≈ 1.074 in (27.28 mm). Tolerances held to ± 0.010 in on ID and ± 0.004 in on cross-section.

• Operating pressure range: Single virgin PTFE ring supports approximately 3,000–3,600 psi static and dynamic; filled PTFE or double backup ring configurations extend capability toward 5,000–5,800 psi.

• Temperature range: −200 °C to +260 °C (−328 °F to +500 °F) for the PTFE ring. PTFE offers a wide temperature range from −100 °F to 500 °F even in its conservative rating. The companion seal material (elastomer) may be the limiting factor.

• Media compatibility: Suitable for hydraulic oils, synthetic fluids, fuels, solvents, acids, gases, and many aggressive chemicals. PTFE is chemically inert, ideal for aggressive environments in chemical processing, oil and gas, and aerospace industries.

• Packaging: Shipped individually.

Who It's For

This ring size is specified by professionals who design, maintain, or source components for sealing systems that use standard -211 O rings.

• Hydraulic system designers seeking robust anti extrusion support for -211 O rings in hydraulic cylinders, valves, and pumps operating at high pressure.

• Maintenance and reliability engineers wanting to eliminate repeat O ring failures and extend maintenance intervals in legacy equipment already using -211 glands.

• OEM buyers and sourcing specialists standardizing on AS568A dimensions across product lines for global compatibility and stock efficiency.

• Process engineers in chemical, oil and gas, power generation, and aerospace industries who require PTFE's chemical inertness and broad temperature range in -211 glands exposed to aggressive media. PTFE backup rings are used in hydraulic cylinders, pneumatic controls, and chemical processing - all environments where reliable sealing is non-negotiable.

If your goal is fewer leaks, longer service life, and predictable performance in high pressure applications, this backup ring fits your needs.

Feature-to-Benefit Highlights

• AS568A-211 groove compatibility – Ensures seamless integration into existing rod and piston glands without redesigning hardware. They are often used alongside O-rings to enhance sealing effectiveness across many applications.

• Solid or split profiles – Choose easy-install split ring configurations for field service or solid rings for maximum extrusion resistance in static and dynamic glands. Back-up rings are used in high-pressure pneumatic systems as well as hydraulic systems.

• Low friction PTFE surface – PTFE offers extremely low friction for dynamic applications, reducing heat and wear on companion elastomer seals in reciprocating and rotary motion.

• Dimensional stability under load – Maintains shape at elevated operating pressure and high temperature, preserving O ring geometry and preventing the clearance gap from opening up during thermal expansion.

• Chemical inertness to common fluids – Supports one backup ring solution across different media - from mineral oils to solvents to acids - using the standard -211 ring size. They are essential in high-pressure sealing applications across a wide range of industries.

FAQ: PTFE Backup Ring AS568A-211

Below are common questions customers ask before ordering AS568A-211 PTFE back up rings.

Will AS568A-211 PTFE backup rings fit my existing -211 O ring grooves? Yes. These rings are manufactured to AS568A-211 dimensional standards and will fit glands designed for -211 O rings, provided your grooves meet standard tolerances (gland depth approximately 0.0973–0.1112 in for static face seals). Groove width must accommodate the O ring plus the backup ring thickness - consult our engineering team if you need verification for your specific application. Proper installation and selection of backup rings are critical for effective sealing.

Should I choose a solid or split PTFE backup ring for size 211? Solid rings deliver the highest anti extrusion performance because there is no cut that could open under extreme pressures. A split backup ring with a scarf cut simplifies installation when disassembly is limited - ideal for field maintenance on hydraulic cylinders or pneumatic systems. For the most demanding applications with very high pressure or rapid cycling, spiral back up rings are also available. Select based on your pressure, maintenance access, and reliability requirements.

Can one AS568A-211 PTFE backup ring handle bidirectional pressure? A single ring protects against unidirectional pressure by blocking the extrusion gap on the low-pressure side. For true bidirectional or reversing system pressure, install two back up rings - one on each side of the -211 O ring. Backup rings increase the pressure rating of sealing systems in either configuration. PTFE backup rings can withstand temperatures from −200 °C to 260 °C, so the same material choice works regardless of direction. PTFE back-up rings prevent O-ring extrusion in hydraulic cylinders operating in both pressure directions.

Ready to Specify AS568A-211 for Your Next Seal Stack?

Stop replacing extruded O rings every maintenance cycle. Standardize on the PTFE backup ring AS568A-211 to protect your seals, extend uptime, and simplify inventory across your high pressure systems. With expertise in virgin and filled PTFE grades, solid, split, and spiral designs, and stock availability in standard quantities, we help you match the right anti extrusion ring to your pressure, temperature, and media requirements.

Contact the Barens team today with your operating pressure, temperature range, and media details - we will recommend the optimal PTFE grade and ring style for your AS568A-211 seal stack.