The O-ring is a commonly used mechanical gasket, seated in a groove and compressed to create a seal. They can withstand a wide range of pressures and temperatures, be used in static and dynamic applications, and are easy to install, tighten, and maintain, making them extremely versatile. They are simple but high-precision components used in a massive range of industries and technical fields worldwide. This guide will provide a few points to keep in mind while selecting the right O-rings for a project.
Sizing for success
O-rings come in an extensive size range, specified either in British Standard or metric sizes. The internal and outer dimensions and cross-section measurements have to be considered before a selection can be made. It has to fit into the gland provided for it without allowing for any gaps, which could compromise the sealing mechanism.
As they need to be flexible and hold up under compression, O-rings are typically made of elastomers. Many factors go into picking the right material: their suitability in working temperatures, their ability to stand up to high pressures, the amount of lubrication required, their compatibility with the substances being sealed in, and other factors like size and cost.
Nitrile rubber is a good option for general-purpose O-rings, as it has excellent oil and water resistance. It is suitable for use in plumbing and automotive maintenance, among other things. However, it has low resistance to ozone and weathering and cannot be used with certain chemicals and solvents. An alternative for use with such items, food-grade equipment, and medical devices is silicone rubber. Silicone resists ozone and weathering, but it is weaker against oils. The selection of material depends on the intended application.
Gaskets of these flexible materials have a measure called their "shore durometer," which is the hardness of a material and its ability to withstand indentation. It's measured on a 0-100 scale, with 100 meaning the material does not give under pressure at all. For general purposes, the recommended shore durometer is 70, as it is neither too soft nor too stiff. Softer compounds stretch easily and may risk extrusion under high-pressure situations. In contrast, harder compounds resist stretching and extrusion and may not perform well on rough surfaces.
Categories Simillar to O-Rings includes Sheet Gaskets, Spiral Wound Gaskets and Tape Gaskets