ED Rings — Hydraulic Port & Manifold Seals

Elastomer port seals for static hydraulic and pneumatic connections — designed for screw-in fitting grooves and manifold port cavities.

Overview

ED rings — also called elastomer port seals or profiled port O-rings — are molded seals with a geometry optimized for the rectangular or trapezoidal grooves found in hydraulic screw-in fittings, valve blocks, and manifold ports. Unlike standard O-rings sized only by inside diameter and cross section, ED profile seals match the groove width, depth, and retention features of the port cavity. The primary application is static sealing at hydraulic port connections: pump and motor interfaces, directional valve stacks, cartridge valve cavities, and inline fitting bodies. The seal compresses between the fitting shoulder and the port bottom when the screw connection is torqued, creating a metal-to-metal stop with elastomeric sealing at the port face. Material selection follows the hydraulic fluid and temperature: NBR 70–90 Shore A for mineral oil HLP/HLP-D systems; FKM for synthetic ester, high-temperature, and aggressive additive packages; EPDM for water-glycol (HFC) and phosphate ester where specified. Hardness affects extrusion resistance — 90 Shore A is common for pressures above 400 bar static when groove geometry permits. ED rings are static seals. Do not use standard port ED profiles in dynamic reciprocating glands — specify rod or piston seals designed for sliding contact. We supply ED profile seals to customer drawings and common DIN 3869 / ISO 6149-style port dimensions. MOQ from 1 piece on custom sizes. Material test certificates and lot traceability available on request.

ED Ring Types

Standard Port ED Profile

Rectangular or slightly trapezoidal cross section matched to the port groove in screw-in hydraulic fittings. Installed in the groove before fitting insertion; compression occurs when the fitting is torqued to specification.

Best for: Hydraulic manifolds, pump ports, valve bodies, inline connectors

Heavy-Duty / High-Pressure Profile

Increased cross section or 90 Shore A compound for static port pressures above 400 bar where groove geometry allows higher squeeze without over-compressing the port cavity.

Best for: High-pressure pumps, intensifiers, static test ports

Metric & Imperial Port Sizes

Sizes aligned to metric thread port families (M8 through M42 and larger) and SAE port sizes. Custom profiles produced from groove dimensions on your drawing.

Best for: Mixed-equipment maintenance, OEM manifold production

Materials

Material	Properties	Best For
NBR 70–90 Shore A	Excellent mineral oil and hydraulic fluid compatibility, −30°C to +100°C typical service	General industrial hydraulics, mobile equipment, standard HLP fluids
FKM 75–90 Shore A	High-temperature and synthetic fluid resistance, −20°C to +200°C continuous	High-temp hydraulics, synthetic ester fluids, aggressive additive packages
EPDM 70–80 Shore A	Water-glycol and phosphate ester compatibility where compound is qualified	HFC fluids, water-based hydraulics, selected fire-resistant fluids

Sizing

Specify port thread size, groove width, groove depth, and material — or send the fitting drawing. We match ED profile to the groove or recommend an equivalent standard size from our tooling library.

Metric port threads

• M8 × 1
• M10 × 1
• M12 × 1.5
• M14 × 1.5
• M16 × 1.5
• M18 × 1.5
• M22 × 1.5
• M27 × 2
• M33 × 2
• M42 × 2
• Custom

SAE / UNF port sizes

• 7/16-20
• 9/16-18
• 3/4-16
• 7/8-14
• 1-1/8-12
• 1-3/8-12
• 1-5/8-12
• Custom

Frequently Asked Questions

What is the difference between an ED ring and a standard O-ring?

Standard O-rings are defined by inside diameter and cross section (AS568, ISO 3601). ED rings match a specific port groove geometry — often rectangular — in hydraulic fittings. Using a round O-ring in a port ED groove may leak or extrude because contact stress is uneven.

Can I replace an ED ring with any O-ring of similar size?

Only if the groove is designed for a round O-ring and dimensions match squeeze requirements. Port ED grooves should receive ED profile seals or the exact replacement specified by the fitting manufacturer drawing.

What torque should I use when installing ED ring fittings?

Follow the fitting manufacturer's torque table for your thread size and pressure rating. Under-torque leaves the seal under-compressed; over-torque damages the port or fitting seat. Lubricate threads with system-compatible fluid, not pipe dope on the seal face.

Which material for water-glycol hydraulic fluid?

EPDM compounds qualified for HFC water-glycol fluids are typical. Standard NBR swells in water-glycol. Confirm fluid type and temperature before ordering.

Do you supply ED rings for DIN 3869 ports?

Yes. Send thread size and groove dimensions or the fitting part number. We supply molded ED profiles in NBR, FKM, and EPDM with certificates on request.