Design of elastomer O-ring vacuum seals

Elastomer O-rings were developed in hydraulics, but design criteria from this field are not suitable in high vacuum technique. In the literature, information on O-ring vacuum seals is normally given in the form of tabulated recipes for groove dimensions. Measurements of the mechanical properties (shown in figures) of O-ring enable us to extend these recipes to a general criterion for high vacuum sealing: a contact pressure at the rubber-metal interface of 13 kg/cm². Design of seals using free rings between flat flanges and seals using rings confined in grooves of rectangular and triangular section is treated. Figures and tables of design parameters are given. Correct design in the case of stretched rings is discussed. Important secondary results include the required compression force and the maximum allowed gap (if required) between mating flanges. Figures deal with these parameters. The influence of tolerances is treated too in the given examples.