O-ring seal

elastomerNBRpolyurethane

Product description A universal sealing element primarily used for static sealing. O-rings are endless round rings with a circular cross-section manufactured to DIN ISO 3601 tolerances and surface requirements. Sealing is achieved by axial or radial compression of the cross-section. O-rings suit static and limited dynamic applications and are offered in various elastomer materials and polyurethane. Assortment boxes are available.

Fields of application

• static
• dynamic (limited)
• single acting
• double acting
• linear
• rotating (inactive)
• oscillating

Main use a simple sealing element primarily for static sealing

Materials Elastomers (e.g. NBR, HNBR, FKM, EPDM, CR, VMQ); polyurethane

Advantages

• universally applicable
• cost-effective
• elastic properties
• wide range of materials
• easy assembly
• compact space requirement
• simple groove design

Main fields of application

• axial-static sealing
• radial-static sealing

Technical values Materials: elastomer, polyurethane
Pressure: up to 200 MPa; from approx. 5 MPa with Back-up ring
Temperature: -60°C to +320°C (material dependent)
Speed: not specified

Definition of O-ring dimensions and ordering sizes inside diameter d1: from approx. 0.70 mm to 5000 mm
cross section d2: from approx. 0.2 mm to 30 mm

Design information Select the largest practicable O-ring cross section (d2) relative to the inside diameter (d1) where possible. The sealing effect results from axial or radial compression of the ring's cross-section when installed. Because elastomers are nearly incompressible, system pressure increases contact pressure on sealing surfaces.

Stretching / compression

• expanded by max. 6%
• compressed by max. 3%

Groove degree of filling The filling level of the O-ring groove must not exceed 80% when installed.

Installation precompaction

• hydraulics: 6%
• pneumatics: 2%

Recommended compression depending on application

• dynamic sealing: 6 - 20%
• static sealing: 15 - 30%

Gap widths / extrusion If the sealing gap is too large, elastomer O-rings can be damaged by gap extrusion. Hardness 90 Shore A O-rings tolerate slightly larger gaps than 70 Shore A O-rings. Use of Back-up rings is recommended from approx. 5 MPa; groove width must be increased for O-ring + Back-up ring combinations.

Installation Instructions

• defined lead-in chamfers; burr-free, rounded transitions
• surface quality Ra < 0.8 µm; Rz < 4 µm
• burr-free rounded holes and slits
• lubrication without solid additives
• use installation tools to pass over sharp edges and corners (e.g. threads)
• dirt-free sealing surface
• do not overstretch the O-ring
• do not warp or twist the O-ring

Caractéristiques / spécifications techniques

• Product: O-ring (endless circular cross-section sealing ring)
• Brand: ULMAN Dichtungstechnik GmbH
• Main use: static sealing (limited dynamic use)
• Materials: NBR, HNBR, FKM, EPDM, CR, VMQ; general: elastomers and polyurethane
• Inside diameter (d1): approx. 0.70 mm – 5000 mm
• Cross section (d2): approx. 0.2 mm – 30 mm
• Pressure rating: up to 200 MPa; from ~5 MPa with Back-up ring
• Temperature range: -60°C to +320°C (material dependent)
• Recommended groove fill: <= 80%
• Stretch limits: expansion max 6%; compression max 3%
• Installation precompression: hydraulics 6%; pneumatics 2%
• Compression for sealing: dynamic 6–20%; static 15–30%
• Advantages: universal applicability, cost-efficiency, elasticity, wide material range, easy assembly, compactness, simple groove design