PAI Kurv-Bak™ hard rubber back-up rings can be made in a variety of materials to help prevent early seal failure at higher pressures.
Back-up Rings are used for one of two purposes. Higher pressures may be sealed by using back-up rings with standard, or tightened, manufacturing tolerances. Alternately, tolerances may be loosened in low pressure applications by using back-ups. Kurv-Bak™ back-up rings may be used in static and dynamic sealing applications.
Precision Associates' hard rubber molded contoured Back-Ups are routinely produced in our 90 durometer Nitrile Compound 5939. This provides sufficient elasticity to permit stretching over the major diameter of a piston and then snap back into the gland of the piston. Compound 5939 has sufficient hardness to resist extrusion of the softer elastomeric O-Ring performing the actual sealing function. You can order Kurv-Baks™ in special materials too! PAI regularly mold them in Fluoroelastomer, EPDM, Aflas® & HNBR.