How Do O-Rings Work


O-Ring is a simple device that makes your sealing effort successful. They are the most common method of preventing leak. O-Ring works in a simple and ingenious way that blocks the pathway through which fluid or airway escapes.

The O-Ring is one of the simplest, most common types of seal for a wide range of static and dynamic applications. The design of the O-ring groove is relatively straightforward — by following well-developed rules for groove geometry, an economical and reliable seal is obtained. The tendency of the O-ring to return to its original shape when the cross-section is compressed is the basic reason an O-ring makes an excellent seal.


It is installed in the groove of one of the surfaces to be sealed. When both the surfaces are bought together, they squeeze the cross-section of the O-Ring. O-Rings are double acting sealing elements. When the introductory squeeze is given (either in axial or radial direction), that is what gives the O-Ring its initial sealing capacity. The mechanical pressure or the pressure transmitted through hydraulic fluid is forced to flow within the gland to produce ‘zero clearance’. The rubber absorbs the layered tolerance of the unit. This maintains the sealed condition. In case if the pressure is high, it squeezes the O-Ring against the wall of the groove helping it to expand and seal against the wall. On releasing the pressure, due to the resilience of the rubber elastomer, O-Ring returns to its normal shape and is ready for similar cycles.


However, if due to increasing pressure, ring deformation is in excess, the O-Ring will extrude out of the extrusion gap. In case the extrusion is too large, the seal will fail after complete extrusion from high pressure. Thus, it is important to choose the right elastomer that has a high capacity to remain in original shape.

This is how O-Ring works, in a simple and effective way.