Hydraulic seal profile reference
Rod seals, piston seals, wiper seals, buffer seals, guide rings, and static gland seals — each profile has a defined function and placement within the cylinder. Selecting the wrong profile produces early failure regardless of compound quality.
Standard cylinder seal arrangement
| Rod seal (primary) | Seals internal hydraulic fluid. Faces inward. Activated by system pressure on exit stroke |
| Buffer seal | Between rod seal and wiper. Absorbs pressure spikes before they reach primary rod seal |
| Wiper seal | Faces outward. Excludes contamination from rod surface on retraction stroke |
| Guide ring (wear ring) | Prevents metal-to-metal contact. Supports side load. PTFE or filled polymer |
| Piston seal | Prevents fluid bypass across piston. Double-acting: two opposing seals |
| Static gland seal | O-ring at gland face. Static application only |
Profile characteristics
O-ring
Circular cross-section. Seals by compression between two surfaces. Used for static face seals, port seals, and low-pressure dynamic applications. For dynamic use above approximately 160–200 bar, back-up rings are required to prevent extrusion through the clearance gap.
Manufactured range: Ø4 mm – Ø600 mm. Materials: NBR, FKM, EPDM, FFKM, Silicone, Neoprene.
U-cup (U-seal / lip seal)
U-shaped cross-section. Pressure-energised — the lip deflects harder against the sealing surface as system pressure increases. The standard primary dynamic seal for hydraulic cylinder rod and piston applications. Single-acting (seals in one direction only). Double-acting pistons use two opposing U-cups.
Dimensional standards: ISO 6195 (wiper), ISO 5597 (rod and piston). Profile confirmation pending for Santoo manufacturing range — contact for specific ISO standard compatibility.
T-seal
T-shaped cross-section with side lobes that prevent rotation and extrusion in the groove. Used in high-pressure dynamic applications — typically above 250 bar — where O-rings would extrude and U-cups would roll. Usually supplied with anti-extrusion back-up rings.
Wiper seal (scraper)
Faces outward from the cylinder. Removes contamination — abrasive dust, particles, water — from the rod surface as the rod retracts. Critical in GCC cement, mining, and construction environments where airborne abrasive dust is present. A failed wiper allows contamination to reach the rod seal, producing rod seal failure from abrasion rather than from compound degradation.
Buffer seal
Sits between the primary rod seal and the wiper. Absorbs high-pressure spikes from load impacts, end-cushion events, and rapid valve cycling before those spikes reach the primary seal. Omitting a buffer seal in high-cycle applications accelerates primary seal fatigue.
Guide ring (wear ring)
Prevents metal-to-metal contact between the rod and gland, or the piston and bore. Supports side loads that the seals are not designed to carry. Manufactured from PTFE (virgin or filled), PEEK, or UHMW-PE. A failed or absent guide ring concentrates side load on the seal profiles, producing accelerated and asymmetric wear.
Dimensional standards table — in preparation
A table of ISO and DIN dimensional standards for each profile type, with groove dimensions and installation tolerances, is in preparation pending confirmation from the Santoo engineering team.
Custom seal cutting
Santoo cuts seals to drawing or measured sample for all profiles listed on this page. Diameter range Ø4–600 mm. Materials: NBR, FKM, EPDM, PTFE, polyurethane.
View seal cutting specRelated guides
Profile selection consultation
Send us your cylinder drawing or specification and we will confirm the correct profile, compound, and dimensions.
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