Unilion^® standard profiles

Unilion seals are based on the U-ring principle. The lips of each seal are initially energised by corrosion resistant metal springs of helicoil, U-spring, or U-finger spring design, according to the seal type.

The spring energises the Unilion seal by providing resilience to the PTFE lips. This radial stress keeps the sealing lips in contact with the shaft / piston and cylinder before system pressure is applied. It also compensates for any slight eccentricity cause by misalignment in the equipment, manufacturing tolerances, bedding-in wear or thermal movement.

When applied, the system pressure enhances the spring action and increases fluid sealing efficiency. Thus radial stress always exceeds the pressure to be sealed. The flat heel of the seal sits firmly in the machined housing groove to keep the lips set at the correct angle for efficient operation.

The result is a long-life, low-friction seal with negligible leakage - even under physically demanding operating conditions involving highly corrosive fluid media or cryogenic temperatures and gases such as CO2 and hydrogen.

These products have been independently 3rd party tested and a range of material options have been validated by James Walker for use in hydrogen service. Contact us for further details.

Below you will find an overview of the standard Unilion profiles available. Details on the spring types, technical data and how to specify your seal can all be found in the Unilion guide. If a bespoke sealing solution is required, please contact us for advice.

Radial seals
Profile	Type	Features
	Unilion U01/U02	Radial seal for static and dynamic duties; suitable as rod or piston seal. Medium to high spring load for positive sealing, but with some friction. Suitable for service with medium to high system pressure. Type U01: Standard profile Type U02: As U01, but with extended heel for higher pressure service.
	Unilion U03/U04	As Type U01, but for reciprocating action only. Contains scraper lip on inside diameter. Type U03: Standard profile. Type U04: As U03, but with extended heel for higher pressure service.
	Unilion U05/U06	As Type U01, but for reciprocating action only. Contains scraper lip on outside diameter. Type U05: Standard profile. Type U06: As U05, but with extended heel for higher pressure service.
	Unilion U20/U21	Radial seal for dynamic duties as rod or piston seal. Low spring load and high deflection provides low friction sealing and compensates for minor eccentricity or misalignment. Suitable for service with low to medium system pressure and / or speed. Type U20: Standard profile. Type U21: As U20, but with extended heel for higher pressure service.
	Unilion U22/U23	As Type U20, but for reciprocating action only. Contains scraper lip on inside diameter. Type U22: Standard profile. Type U23: As U22, but with extended heel for higher pressure service.
	Unilion U24/U25	As Type U20, but for reciprocating action only. Contains scraper lip on outside diameter. Type U24: Standard profile. Type U25: As U24, but with extended heel for higher pressure service.

Radial flange seals
Profile	Type	Features
	Unilion U07	As Type U01, but has flange that is clamped to prevent undesirable movement of the seal. Rotation can occur with standard designs, due to thermal expansion
	Unilion U08	As Types U01 and U07, but for reciprocating action only. Contains scraper lip on inside diameter.
	Unilion U26	As Type U20, but has flange that is clamped to prevent the seal rotating with the shaft. Rotation can occur with standard designs, due to thermal expansion and other effects with dynamic applications.
	Unilion U27	As Types U20 and U26, but for reciprocating action only. Contains scraper lip on inside diameter.

Axial seals
Profile	Type	Features
	Unilion U09	Axial seal for static applications as in Type U01. Used as an internal face seal.
	Unilion U10	Axial seal for static applications as in Type U01. Used as an external face seal.
	Unilion U28	Axial seal for static or dynamic applications as in Type U20. Used as an internal face seal.
	Unilion U29	Axial seal for static or dynamic applications as in Type U20. Used as an external face seal.

Axial face seals

Our axial face seals Unilion Type U30 and U31 contain a heavy duty, higher load spring. We recommend these seals for extreme static sealing conditions.

Unilion U30: Axial seal for internal pressure

Unilion U31: Axial seal for external pressure