AS3582-114 - Silicone O-Ring

AS3582-114 – Aerospace Standard EPDM Phosphate Ester Hydraulic O-Ring

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Overview

The AS3582-114 is a flight-critical, preformed O-ring packing seal manufactured to the stringent Aerospace Standard (AS3582). This component is specifically engineered from an Ethylene Propylene Diene Monomer (EPDM) rubber compound, chosen for its exceptional compatibility with phosphate ester-based hydraulic fluids, such as Skydrol®, HyJet™, and similar fluids used extensively in modern transport category and business aircraft hydraulic systems. Its primary function is to create a positive, leak-free static seal in fittings, valves, and other components operating within these demanding fluid environments.

The -114 suffix designates the O-ring's size according to the AS568 dimensional standard. The material properties dictated by AS3582 ensure reliable performance across a wide temperature range and resistance to degradation from the aggressive chemical nature of phosphate ester fluids, which would rapidly attack and destroy common Nitrile (NBR), Fluorocarbon (FKM), or Silicone seals. Using a certified AS3582-114 O-ring is essential for maintaining the integrity and safety of these high-pressure hydraulic systems.

Key Features

• Phosphate Ester Fluid Compatible: Fabricated from a specialized EPDM compound specifically formulated for long-term resistance to Skydrol® and other phosphate ester hydraulic fluids.

• AS3582 Standard Compliance: Guarantees adherence to the aerospace standard for material composition, physical properties, dimensional tolerances, and quality control for EPDM O-rings.

• AS568 Size -114: Precisely dimensioned according to the AS568-114 standard for a perfect fit in corresponding glands.

• Wide Temperature Range: Engineered to maintain sealing integrity and flexibility in typical aerospace hydraulic system temperatures ranging from approximately -65°F to +300°F (-54°C to +149°C).

• Distinctive Color: Typically purple in color for positive visual identification, preventing accidental installation in petroleum-based fluid systems where EPDM is incompatible.

• Designed for Static Sealing: Provides a reliable seal between two stationary surfaces under pressure.

Technical Specifications

• Part Number: AS3582-114

• Component Type: Preformed O-Ring Packing Seal

• Governing Specification: AS3582

• Material: Ethylene Propylene Diene Monomer (EPDM) Rubber ( Not Silicone )

• Hardness: 70 ± 5 Durometer Shore A

• Color (Typical): Purple

• Dimensions (AS568-114):

  • Inside Diameter (ID): 0.551 inches

  • Cross-Section (CS): 0.103 inches

• Typical Temperature Range: -65°F to +300°F (-54°C to +149°C)

• Compatible Fluids: Phosphate Ester Hydraulic Fluids (e.g., Skydrol®, HyJet™)

• Incompatible Fluids: Petroleum-based fluids (fuel, oil, mineral hydraulic fluid), hydrocarbon solvents, Silicone fluids.

Aircraft Compatibility

The AS3582-114 is a standard hardware component used in the hydraulic systems of virtually all modern commercial airliners and many business jets that utilize phosphate ester fluids.

• Representative Aircraft Platforms:

  • Boeing 7-Series Airliners

  • Airbus A3XX Series Airliners

  • Bombardier Global and Challenger Series

  • Gulfstream G-Series

  • Dassault Falcon Jets

  • Embraer E-Jets and Phenom Series

  • Textron Aviation Citation models specifying phosphate ester fluid.

Note: Verification of applicability is the responsibility of the installer. Always consult the current version of the aircraft or component's Illustrated Parts Catalog (IPC) and maintenance manual to confirm part number eligibility.

Applications

• Static sealing in hydraulic system components operating with phosphate ester fluids, including:

  • Tube fittings

  • Valves

  • Actuators

  • Pumps and reservoirs

  • Brake system components

Why Choose AS3582-114?

Material compatibility in hydraulic systems is non-negotiable. Phosphate ester fluids like Skydrol® are extremely aggressive and will cause catastrophic failure (swelling, softening, disintegration) of standard Nitrile, Fluorocarbon, or Silicone O-rings. Only EPDM, manufactured to the AS3582 standard, is suitable. Using a certified AS3582-114 O-ring is the only way to guarantee installation of the correct EPDM material, preventing leaks, system contamination, and potential failure of critical hydraulic systems. The distinctive purple color serves as a vital safeguard against material mix-ups during maintenance.

The chemical resistance of the AS3582-114 O-ring stems from the molecular structure of Ethylene Propylene Diene Monomer (EPDM). EPDM is a non-polar synthetic rubber, characterized by a saturated polymer backbone derived from ethylene and propylene monomers, with a small amount of a diene monomer incorporated to allow for sulfur vulcanization. This predominantly non-polar, saturated structure is key to its performance. Phosphate ester fluids like Skydrol® are highly polar. According to the chemical principle "like dissolves like," the non-polar EPDM is largely resistant to attack and swelling by these polar fluids. Conversely, petroleum-based oils and fuels are non-polar hydrocarbons, which readily attack and swell the non-polar EPDM. Silicone rubbers, while having a wide temperature range due to their siloxane backbone, lack the chemical structure needed to resist the aggressive phosphate ester chemistry and would fail rapidly in this application. The AS3582 standard ensures the correct EPDM polymer and cure system are used for optimal performance in Skydrol®.

Note: This component has a finite shelf life defined by standards like ARP5316. The cure date marked on the packaging must be verified prior to installation. It is a single-use part; a new O-ring must be used every time a fitting is reinstalled. Meticulous cleanliness is required during installation. The O-ring must be lubricated only with clean system hydraulic fluid (Skydrol®) or an approved phosphate ester-compatible lubricant. Never use petroleum-based grease, oil, or silicone grease for lubrication. Ensure positive material identification: this EPDM O-ring is typically purple.

Documentation

The base standard for this part is Aerospace Standard AS3582. This is a controlled document managed by SAE International. OEM-specific application and installation data is contained within the aircraft's maintenance and parts manuals.