For hydraulic cylinders, pneumatic actuators, and fluid processing systems, an elastomeric seal is the critical defense against pressure loss and contamination. At Pneu-Draulics, high-performance O-ring seals form the core of our fluid power inventory. We supply a complete range of standard and custom O-rings across AS568 and metric profiles, backed by over 40 years of sealing expertise and ISO 9001:2015 quality management.

Whether you require a MIL-spec elastomer, a bulk industrial O-ring kit for MRO inventory, or custom O-ring cross-section tolerances for critical OEM assemblies, our engineering team sources and verifies every seal to spec.

Our O-Ring Design and Manufacturing Capabilities

Pneu-Draulics maintains inventory across AS568 and ISO 3601 metric sizes – the full range of cross-sections used in North American and international equipment.

Our bulk O-ring supply program is built for procurement teams, OEMs, and rubber and gasket houses that need consistent compound and dimensional traceability across large orders.

To accommodate specialized OEM and distribution requirements, Pneu-Draulics provides complete custom manufacturing and supply chain services:

  • Custom O-ring profiles. We manufacture engineered profiles to exact customer prints or co-develop custom geometries during sealing design consultation.
  • Private-label kitting. We supply custom industrial O-ring kits with branded packaging, custom labeling, and tailored component counts for distributors and MROs.
  • Vendor-managed inventory (VMI). We structure stocking programs that maintain critical seal reserves locally, reducing lead times for high-turnover parts.

We also supply Parker O-rings verified to MIL-I-45208A, MIL-P-4861B, and AMS material specifications. If your application carries a third-party certification requirement, we can meet it. To get started, download our custom seal request form.

Our Precision Tolerances and Quality Certification

Dimensional accuracy determines whether a seal performs or leaks. O-ring cross-section tolerances for AS568 sizes follow SAE standards. Metric O-rings follow ISO 3601, which sets tolerances on both inside diameter and cross-section across four size groups.

All Pneu-Draulics products are distributed under our ISO 9001:2015 quality management system. Every order is traceable to material, compound, and dimensional specifications. We maintain full documentation to support customers with audit or certification requirements.

Our O-Ring Materials [H2]
The right compound depends on your fluid, temperature range, and application type. Below are the core materials Pneu-Draulics carries.
Nitrile (Buna-N) [H3]
Nitrile (NBR) is the standard elastomer for petroleum-based oils, hydraulic fluids, and pneumatic systems. Standard NBR operates effectively from -40°F to 250°F and is available in standard 70 and 90 Shore A durometers.
For high-cycle dynamic applications or higher thermal exposure, Hydrogenated Nitrile (HNBR) provides enhanced performance. Rated up to 325°F, HNBR offers superior resistance to ozone, weathering, and mechanical abrasion compared to standard NBR.

Our O-Ring Materials

The right compound depends on your fluid, temperature range, and application type. Below are the core materials Pneu-Draulics carries.

Nitrile (Buna-N)

Nitrile (NBR) is the standard elastomer for petroleum-based oils, hydraulic fluids, and pneumatic systems. Standard NBR operates effectively from -40°F to 250°F and is available in standard 70 and 90 Shore A durometers.

For high-cycle dynamic applications or higher thermal exposure, Hydrogenated Nitrile (HNBR) provides enhanced performance. Rated up to 325°F, HNBR offers superior resistance to ozone, weathering, and mechanical abrasion compared to standard NBR.

FKM

FKM (fluorocarbon elastomer) is the right call when nitrile falls short. Rated to 400°F, Viton resists fuels, aromatic hydrocarbons, and a broad range of chemical media. Aerospace, automotive, and chemical processing applications commonly specify FKM where fluid compatibility and heat tolerance are non-negotiable.

Not sure if your fluid is compatible? Our fluid compatibility chart is a useful starting point.

EPDM

EPDM handles water, steam, and brake fluids well – but petroleum-based oils are off the table. Water treatment, food processing, and HVAC applications are the most common fits.

High-Performance Compounds: FFKM and Fluorosilicone

Perfluoroelastomer (FFKM) compounds deliver near-universal chemical compatibility and extreme thermal stability, exceeding operating temperatures of 500°F. We supply premium Parker FFKM formulations that match performance requirements in applications calling for Kalrez® or Chemraz® equivalents.

Fluorosilicone (FVMQ) combines the wide low-temperature flexibility of silicone with the chemical and fluid resistance of fluorocarbons. It is widely specified for aerospace fuel handling systems and cold-weather static seals exposed to hydrocarbon media.

Choosing the Right O-Ring Material for Your Application

Proper seal selection requires evaluating key system operational parameters to prevent premature failure or fluid degradation.

Consider these foundational engineering guidelines during material selection:

  • Temperature limits. Always specify compounds based on peak continuous and transient thermal limits rather than average operating temperatures.
  • Pressure & hardness. Utilize higher durometer compounds (e.g., 90 Shore A) or anti-extrusion backup rings when operating at high pressures to prevent seal nibbling. •
  • Mating surface finish. Dynamic applications require tighter surface finish specs (typically 8–16 µin Ra) compared to static face seals to prevent abrasive wear.

For compound-by-compound compatibility data, the O-Ring Handbook is the right reference.

Static vs. Dynamic O-Ring Applications

Static applications (face seals, flange seals, threaded port seals) hold the O-ring against a fixed surface. Higher squeeze and softer durometers are generally acceptable.

Dynamic applications (reciprocating pistons, rotating shafts, oscillating joints) need tighter tolerances and a controlled surface finish. For high-cycle dynamic seals, 90-durometer compounds or HNBR typically outlast standard 70-durometer nitrile.

Optimize Your Fluid System Reliability with Pneu-Draulics

Securing the correct elastomeric seal minimizes unplanned downtime, extends MRO maintenance cycles, and ensures leak-free fluid power performance. Supported by four decades of technical expertise and an ISO 9001:2015 quality framework, Pneu-Draulics delivers reliable standard, metric, and custom sealing solutions tailored to your operational needs.

Use our interactive Elastomer Selection Matrix tool to help you find the ideal aerospace and industrial seal compound based on your unique specifications.

Ready to order? Access our Express Ordering Portal to submit known part numbers and standard AS568/ISO sizes for immediate processing.

Need custom engineering or bulk supply? Request a quote today to consult with our application specialists on material selection, custom tolerances, or inventory stocking programs.