Danish
Updated: 10 October 2025
Published: 8 August 2019
O-Lok (ORFS) fittings – the safe choice for leak-free high-pressure applications
O-Lok from Parker Hannifin are ORFS (O-Ring Face Seal) fittings for tubes in hydraulic systems. The sealing principle is an O-ring in the fitting's sealing face, providing a robust, vibration-proof and completely tight connection – particularly well suited to high pressure.
The simplest and most effective way to use an O-Lok fitting is to connect it with Parflange tube.
Why choose O-Lok?
- Leak-free when correctly assembled – ideal for high pressure (up to 630 bar)
- Complies with SAE J1453 and ISO 8434-3
- Materials: steel and stainless steel with excellent corrosion resistance
- Sizes from ¼” to 2”
- Flexible: can be adapted to metric and inch tubes
- Easy to fit and service – lateral removal possible in tube systems
- Reliable for construction machinery, mining, agriculture and other heavy equipment
Typical applications
- Construction machinery: excavators, loaders, dumpers
- Agriculture: tractors, combine harvesters, balers
- Mining and heavy industry: presses, cranes, lifts
- Stationary installations: hydraulic power packs, test benches
Materials, pressure and dimensions
- Pressure: up to 630 bar (depending on dimension, material and application)
- Materials: carbon steel and stainless steel with high corrosion resistance
- Dimensions: ¼”–2” (selection depends on variant)
- Sealing: replaceable O-ring in the face seal for easy service
Typical causes of leakage
- Damaged or incorrect O-ring (material/dimension)
- Contamination on sealing faces
- Twisting/misalignment during assembly
- Over- or under-tightening
Products and accessories at Hymatik
Download and print our wall chart of O-Lok fittings.
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