A universal applicable sealing element, used mainly for static sealing. Tolerance and surface are according to the DIN ISO 3601. An O-ring is an endless round ring that has a circular cross-section. It is extremely efficient and acts as a sealing element for static and subordinate dynamic applications.
The sealing effect comes into play during installation due to the axial or radial compression of the cross section. O-rings are available in a variety of different elastomer materials. The most common are NBR, HNBR, FKM, EPDM, CR and VMQ. We would be pleased to offer you various O-ring assortment boxes upon request.
O-ring
Fields of application
static
dynamic
single acting
double acting
Linear
Rotating
oszilating
Main use
a simple sealant mainly for static sealing
Materials
Elastomere, Polyurethane
Advantages
- universally applicable
- cost-effective
- elastic properties
- wide range of materials
- easy assembly
- small space requirement
- simple groove design
O-rings are used in various application fields and industrial sectors.
Main fields of application:
- axial-static sealing
- radial-static sealing
The use of O-rings for dynamic sealing is limited.
Technical values
Materials
elastomer, polyurethane
Pressure
up to 200 MPa
from 5 MPa with Back-up ring
from 5 MPa with Back-up ring
Temperature
-60°C / +320°C (material dependent)
Speed
-
Maximum values temperature, speed and pressure are simultaneously not applicable! The values vary in dependence of material and media. For technical queries please contact our application consultants – we have the right solution for you.
More O-rings
PTFE O-ring
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
The sealing effect
The sealing effect of the o-ring is the result of the axial or radial compression of the rings cross section when it is installed. The o-ring is considered to be an active sealing element due to the almost incompressible behavior of the elastomer materials so that the pressure on the sealing surfaces is even increased as a result of the system pressure.
Design Information
In general:
In any given application, it is always prudent to adopt the largest possible O-ring cross section in relation to the inside diameter d1 when selecting the cross section d2.
Stretching/compression:
In dependence of the given application at a radial installation, o-rings can be:
- expanded by max. 6%
- compressed by max. 3%
Groove degree of filling:
The filling level of the O-ring groove must not be > 80% when installed. For special applications such as vacuum, please contact our application consultants.
Installation precompaction:
The sealing effect of the o-ring is the result of its initial compression. Minimum values are for:
- hydraulics 6%
- pneumatics 2%
Depending upon the application, the following values should be achieved:
- dynamic sealing 6 - 20%
- static sealing 15 - 30%
Gap widths:
If the sealing gap is too large, the elastomer O-ring will be destroyed due to gap extrusion.
O-rings made of materials with a hardness of 90 Shore A, allow slightly larger gap widths than 70 Shore A of standard O-rings.
Basically, the use of Back-up rings are recommended from a pressure of approx. 5 MPa. It should be noted that the groove width for the O-ring with Back-up ring combination must be enlarged.
Installation Instructions
To exclude possible sources of error, ensure that the following points are observed for the sealing function when installing o-rings:
- defined lead-in chamfers, burr free, rounded-off transition,
- Surface quality Ra < 0.8 µm.; Rz < 4 µm
- burr-free rounded-off holes and slits
- Lubrication (without any solid additives)
- Installation tools to pass over sharp edges and corners (e.g. threads)
- dirt-free sealing surface
- the O-ring must not be overstretched
- the O-ring must not be warped or twisted
Your contact person for
Technology - General sealing topics, special constructions
Ms. Karen Goller
Do you have any questions, ideas, or suggestions? We are more than happy to assist you with advice. In person, over the phone, or digitally
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