Parker Fluid Connector Group
EO and EO-2 Metric Bite Type Fittings


  • EO
  • EO-2

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Features of EO:

  • Visible Bite: The critical front bite of the progressive ring is clearly visible to tube fitters & inspectors. The presence of the recommended bite virtually eliminates any risk of catastrophic blow-off. This is a very important safety feature.
  • Sealing Capability: EO fittings have demonstrated a remarkable ability to remain leak free under various service conditions ranging from sealing high vacuum and small molecules gases to high pressure hydraulic fluids.
  • Distributed Stresses: Stresses due to service flexural loading are distributed at several points in the joint, thus stress concentration in the bite is minimized.
  • Vibration Control: The rear bevel of the ferrule firmly grips tubing, thus dampening the effects of system vibration in the joint.
  • Progressive Ring Design: The progressive ring design provides a second bite for improved reliability and higher working pressure capability. This design also decreases the risk of improper assembly because of the sharp, high torque rise which occurs when the fitting is properly tightened.
  • Envelope Size: EO fittings are relatively small and compact, making it a suitable selection for plumbing in limited or tight space.
  • Temperature Rating: EO fittings are suitable for subzero through elevated temperature applications. Service temperature rating is limited by the material chosen.
  • Compatibility: Since EO fittings can be manufactured from a wide range of metals, its compatibility factor with various fluids and atmospheric conditions is virtually limitless. One simply has to select and specify EO fittings from an acceptable material that best satisfies the service conditions.
  • Tube Wall: EO fittings are suitable for use with light wall, medium wall, heavy wall, and extra heavy wall tubing. (Light wall tube may require support sleeve (VH), as shown in Assembly/Installation Section.)
  • Re-Usability / Remakeability: Joints can be disassembled and reassembled many times to facilitate system maintenance. This reduces the labor and material costs that would otherwise result from tube and fittings replacement.
  • Assembly: No expensive, complicated tooling is necessary to assemble EO fittings. Assembly is simple when the procedures described in the Assembly / Installation section are followed (see pages S28 - S33).
  • Materials: EO fittings can be manufactured from almost any metallic material. The more popular materials currently used for EO fittings are: stainless steel, carbon steel, and brass. On request, the Tube Fitting Division will machine EO fittings from other appropriate material specified by users.
  • Manufacture: EO fittings are manufactured under tight quality control which ensures that the product routinely satisfies or surpasses the requirements of the pertinent industrial standards.
  • World Wide Popularity: The bite type fitting design has worldwide acceptance and is especially popular in Europe.
  • Superior Plating: Superior plating gives Parker steel tube fittings unmatched protection against red rust. In neutral salt spray test per ASTM B117, Parker EO and EO2 fittings substantially exceeded the SAE requirement of 96 hours to red rest.
  • Finish: Steel EO fittings have a zinc clear Chromium-6 Free finish. This finish provides good corrosion protection. 
  • Silver Plated Nuts: Stainless steel tube nuts are prelubricated with silver plated threads (size 15L-42L, 12S- 38S). Thread galling is eliminated and assembly torque is reduced as much as 40 percent. This increases the speed and efficiency for stainless steel fitting assembly.
  • Availability: EO fittings are available as standard in over thirty different configurations, and as many as twenty-seven different size combinations in some configurations.
  • Configurations: Popular configurations for EO fittings are shown in the Visual Index. Other configurations can be manufactured on request.

Features of EO-2:

  • Sealing Capability: An elastomeric seal forms the primary sealing element, thus assuring leak-free sealing. Even low-viscosity media such as water or gas are hermetically sealed. Hydraulic systems, therefore, do not “sweat” at fittings.
  • High Pressure Resistance: EO-2 fittings are rated up to Pmax 900 bar. Sealing lip and seal arrangements have both been designed so that the sealing effect is supported by system pressure. The interaction of the retaining ring and the integrated preassembly tool results in uniform and reliable fitting assembly.
  • Durability: The elastomeric seal does not require any retightening even after years of operation under severe working conditions.
  • Bite Control: The ideal bite depth is controlled by the fitting design rather than by the fitters force. Closing the gap at the end of the manual assembly, the fitter gets clear signal that setting is completed and the joint is ready for inspection.
  • Functional Nut: Individual components such as the retaining ring or seal cannot be lost, forgotten, confused or assembled in the wrong orientation. This dramatically saves assembly cost and helps to avoid dangerous assembly errors.
  • Assembly Cost: With less than 10 seconds cycle time on the EOMAT III/A (actual presetting process: 1.4 seconds), the cost of presetting EO-2 is extremely low.
  • Integrated Preassembly Tool: Each EO-2 Functional Nut comes assembled with an integrated assembly tool that makes sure that the retaining ring securely cuts into the tube surface without damaging the sensitive inner cone of the fitting body. This greatly reduces the danger of tube blow-off, even when using stainless steel tube.
  • Unlimited Presetting Tool Lifetime: When EOMAT machines are used for cost-efficient presetting, the preassembly tools do not wear out as they are only in contact with the rubber seal. This avoids dangerous blow-off which can result when traditional bite-type fittings are assembled using worn presetting tools.
  • Make-up: From the wrench-tight position of the preset EO-2 joint, one short pull on the wrench (approx. 1/6 to 1/4 turn) gives the assembly a quick high rise to required torque. EO-2 fittings have a solid “hit-home-feel” and excellent over-torque resistance.