Synertech Stock
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STU & Quad-Ring (X-Ring) Special Static Seals
The special profile static sealing rings of the STU series and the four-lobed Quad-Ring (X-Ring) profiles represent the high-reliability evolution over standard commercial O-rings. Specifically engineered for heavy-duty static and quasi-static applications, these profiles eliminate spiral twisting within the groove and guarantee superior structural stability. The lobed profile of the Quad-Ring reduces the required radial preload, minimizing compression set and doubling the sealing barriers thanks to the geometry of four active lips. The STU series, featuring a heavy-duty contoured design, is ideal for the static isolation of flanges, hydraulic fittings, and valve blocks subjected to severe cyclic stresses.
| Profile | Geometric characteristics and application |
|---|---|
| Quad-Ring / X-Ring Type | Four symmetric lobes profile. It prevents rolling in the groove, distributes contact pressure uniformly across two lips per side, and ensures excellent sealing with lower radial preload. |
| STU Standard Type | High-stability contoured static profile ring. Specially developed to eliminate extrusion in industrial flange housings, compensating for micro-roughness on machined metal surfaces. |
| Material / compound | Hardness | Temperature | Max pressure |
|---|---|---|---|
| NBR Nitrile Rubber | 70 / 80 ShA | −30 / +100 °C | 15 MPa without BK |
| FKM Fluoroelastomer / Viton | 75 / 85 ShA | −20 / +200 °C | 20 MPa without BK |
| EPDM Ethylene-Propylene | 70 ShA | −45 / +130 °C | 10 MPa static apps |
| PU Hi-Tech Polyurethane | 93 ShA | −35 / +100 °C | 40 MPa high resistance |
Anti-Twisting Design
The overall square cross-section and the four lobes of the X-Ring eliminate the risk of rolling or twisting inside the groove during assembly and pulsating operations.
Low Compression Set
The lobed geometry requires lower initial squeeze compared to a standard O-ring of the same cross-section, drastically extending the service life of the seal.
Doubled Sealing
The presence of two sealing lips per side creates a double static hydrodynamic wedge that optimizes fluid retention even with very low viscosity fluids or gases.
| Manufacturer | Quad-Ring / X-Ring Profile | STU Static Seals Profile |
|---|---|---|
| Net Seals | X-Ring / QR Series | STU Static Seals Series |
| Freudenberg (Simrit) | X-Ring Profile | PR / SK Static Profile |
| Parker Prädifa | Quad-Ring Profile | HS / OS Profile |
| Dichtomatik | NBR/FKM X-Ring Profile | Gray/black static profile |