INDUSTRY COMPONENT

Seals (O-rings)

O-rings are torus-shaped elastomeric seals used in pneumatic and hydraulic systems to prevent fluid leakage between mating surfaces in air valves.

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Component Specifications

Definition
O-rings are precision-engineered sealing components with a circular cross-section designed to fit into grooves and create a static or dynamic seal between two or more parts. In air valve applications, they prevent compressed air leakage around spools, shuttles, and ports by deforming under pressure to fill microscopic gaps. Their effectiveness depends on proper gland design, material compatibility, and installation.
Working Principle
O-rings function through elastic deformation and controlled compression. When installed in a gland (groove), they are compressed radially or axially, creating initial sealing contact. Under system pressure, the O-ring is forced against the low-pressure side of the groove, increasing sealing force proportionally to pressure (self-energizing). In dynamic applications (like spool valves), they maintain sealing through controlled friction and lubrication while accommodating minor movements.
Materials
Common materials include Nitrile Rubber (NBR) for general pneumatic applications (-40°C to 120°C, petroleum resistance), Fluorocarbon (FKM/Viton) for high-temperature/high-chemical resistance (-20°C to 200°C), Ethylene Propylene Diene Monomer (EPDM) for steam/water resistance (-50°C to 150°C), and Polyurethane (PU) for high wear resistance. Material selection depends on temperature range, media compatibility (air, lubricants), and dynamic requirements.
Technical Parameters
  • Inner Diameter 2mm to 500mm
  • Compression Set <25% (per ASTM D395)
  • Pressure Rating Up to 40 MPa static, 20 MPa dynamic
  • Temperature Range -40°C to 200°C (material dependent)
  • Hardness (Shore A) 70 to 90
  • Cross-Section Diameter 1.5mm to 10mm
Standards
ISO 3601, AS 568A, DIN 3771, JIS B 2401

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Seals (O-rings).

O-ring seals pneumatic seals air valve seals elastomeric seals ISO 3601 Nitrile O-rings FKM seals sealing components spool valve seals Seals (O-rings) Seals (O-rings) in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Air Valve (Spool/Shuttle)

A directional control valve that regulates airflow in pneumatic systems by shifting a spool or shuttle mechanism.

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Engineering Analysis

Risks & Mitigation
  • Extrusion under high pressure
  • Compression set leading to leakage
  • Chemical degradation from incompatible media
  • Abrasion from poor surface finish
  • Installation damage during assembly
FMEA Triads
Trigger: Excessive clearance between mating parts
Failure: Extrusion - O-ring material forced into gap, causing permanent damage
Mitigation: Design glands with proper clearance (per ISO 3601), use backup rings for high pressure, specify appropriate hardness
Trigger: High temperature or improper material selection
Failure: Compression set - O-ring loses elasticity and fails to rebound
Mitigation: Select materials with low compression set (e.g., FKM), ensure operating within temperature limits, consider energizers
Trigger: Incompatible fluids or lubricants
Failure: Chemical degradation - swelling, cracking, or hardening
Mitigation: Verify chemical compatibility charts, use appropriate seals (e.g., EPDM for water, FKM for oils), test with actual media

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
ISO 3601-1 Grade N (normal) for general applications, Grade S (special) for precision applications. Dimensional tolerances typically ±0.10mm on cross-section, ±0.30mm on inner diameter.
Test Method
Pressure testing per ISO 228, compression set per ASTM D395, hardness per ISO 48, fluid resistance per ISO 1817, extrusion resistance per ISO 2230.

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Frequently Asked Questions

What causes O-ring failure in air valves?

Common failures include extrusion (excessive clearance), compression set (permanent deformation), chemical degradation (incompatible media), abrasion (poor surface finish), and installation damage (twisting, cutting).

How do I select the right O-ring material for pneumatic applications?

Consider operating temperature, media compatibility (compressed air may contain oil/water), dynamic/static application, pressure, and environmental factors (ozone, UV). NBR is standard for general pneumatics; FKM for high-temp or aggressive environments.

What is the proper gland design for O-rings in spool valves?

Glands should provide 15-30% cross-sectional compression, proper clearance to prevent extrusion, adequate volume to accommodate swell, and smooth surfaces (Ra < 0.8 μm). Follow ISO 3601-2 for dimensional standards.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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