Hydraulic Sealing System
hệ thống làm kín thủy lực
Also known as: hydraulic seals · hydraulic cylinder seal kit · piston rod seals
A hydraulic sealing system comprises piston seals, rod seals, wiper seals, guide rings, and O-ring static seals working together to contain hydraulic fluid at pressures of 10–35 MPa in cylinders and actuators.
Technical Detail
A complete hydraulic cylinder seal kit typically includes: (1) Piston seal — primary dynamic seal preventing bypass flow past the piston (polyurethane U-seal or double-acting lip seal). (2) Rod seal — prevents fluid leakage along the piston rod out of the cylinder (asymmetric lip profile, polyurethane or NBR). (3) Wiper/scraper seal — removes contamination from the rod as it retracts (prevents ingress of dirt/water). (4) Guide rings (wear rings) — bear radial loads, preventing metal-to-metal contact in the bore. (5) O-ring static seals — sealing cylinder end caps, ports, and static joints. Material selection depends on fluid type: mineral HLP oil → NBR or PU; phosphate ester (Skydrol) → EPDM; water-glycol → EPDM; fire-resistant fluid HFD → FKM. Operating conditions in Vietnam industrial hydraulics: 160–250 bar (16–25 MPa), 40–80°C, mineral oil — NBR 70 Shore A rod seals and guide rings are standard.
Reference Standards
- ISO 7425-1 (piston seals)
- ISO 7425-2 (rod seals)
- ISO 10766
Related Terms
- NBR (Nitrile Butadiene Rubber) — NBR (Nitrile Butadiene Rubber) is the most widely used O-ring and gasket elastomer, offering excelle…
- Dynamic vs Static Seal — A static seal prevents leakage between non-moving surfaces (flange faces, port plugs); a dynamic sea…
- O-Ring Groove / Gland Design — O-ring groove (gland) design specifies groove depth, width, and surface finish to achieve 15–25% dia…