Such a device is a ring of an elastic material that is shaped like a "bull." A bull is a geometric body that is shaped like a donut -- circular with a hole in the center. Some o-rings may have to ring differently, but their section is always circular.

This often underappreciated device can ensure tightness between pressures ranging from vacuum up to 500 Kg/cm^3. They are used for static applications and for alternative travel movements (pistons and piston). Such toroidal rings will also accept rotating slow movements (speeds below 0.5 m / s).

These typically-rubber rings are installed in slots practiced for this purpose. The game between the elements joined should be smaller the greater the pressure to contain. From 200 bar, the game should be as few as a couple of microns. Otherwise, the improper bond can cause the phenomenon of extrusion.

The Rubber O-ring

When choosing one of these devices for your sealing needs, the most common manufacturing material is rubber. The rubber rings are highly effective, but there are a few instances that will reduce the life of the seal.

- High temperature bonds, making them more susceptible to chemical damage
- Stretching the seal more than five percent will damage the seal

Measuring for Proper Fit

When choosing an o-ring for your sealing needs, the fit will need to be perfect. Many are measured with the use of inside diameter and cross section width. The inside diameter is the diameter of the ring on the inside of the rubber. The cross section width is the distance across the middle of the ring.

Specialized Products

Many manufacturers will carry every size o-ring you could possibly need for the bond between two joints. However, if there is a unique instance where a traditional size will not fit the opening perfectly, they can be molded to fit within a few microns.

The "rubber donut" is especially important in diving and related practices. When two joints must hold without letting in water or air, the rubber toroidal fits the situation. Of course, ensuring tightness in any kind of diving equipment -- which must typically be water proofed -- is very important. Thus we can find them in all kinds of scuba gear such as the regulators of the air tanks, the pressure gauge, underwater flashlights, cameras, etc. In general, we will find these rubber sealers wherever the water cannot enter and cannot leave air.

The most common household usage for the o-ring is the outdoor hose and the kitchen faucet.