Important considerations for selecting microminiature Orings

In any sealing application, correct O-ring selection is the result of a number of design considerations including dimensions, chemical compatibility and the ability to resist pressure and temperature extremes. In microminiature applications the importance of some of these considerations increases as the size of the O-ring decreases.

Microminiature designs leave less room for inaccuracies, requiring higher precision and tighter tolerances. It is helpful to pay particular attention to some basic sealing concepts when selecting a microminiature O-ring for your application. These include:

• Sealing Pressure - Sealing pressure is the force exerted by compression of the seal between the mating surfaces forming the gland itself and external forces (i.e. the fluid being sealed) transmitted through the seal. A physical barrier is formed when the force from compressing the seal and pressure applied by the fluid being sealed causes the seal to fill all leak paths.
• Low Pressure Sealing - In a low pressure sealing application, system pressure does not cause a noticeable increase in the seal's sealing force. Because of this, all sealing force must come from the ability of the seal to deform and create a barrier by compression of the seal. Surface finish on both the seal and gland are critical to an effective seal.
• High Pressure Sealing - In a high pressure sealing application, system pressure causes a noticeable increase in the seal's sealing force to fill all leak paths. Because this pressure activates the seal, the compression of the seal and surface roughness are not as important as in low pressure sealing.

For more information download our MicrOrings brochure.