be provided by simple dimples or the like in the housing which protrude into the housing chamber and contact the filter cartridge 22 according to an important aspect of the invention the end cap 28 and the end 32 are dimensioned such that the elastic stresses that remain in the components as a result of the interference fit are optimal throughout the life of the assembly 10 in order to determine the optimal initial dimension of the end cad bore 30 relative to of the end 32 the initial and residual stress and strain induced in the end cap 28 and or the end 32 the fitting 20 as a is close to the interference must be considered for our poses of explanation only the stress and strain induced in the end cap will be considered because the modulus of elasticity of the end cap 28 is typically much greater than that of the fitting 20 where the modulus of elasticity of the fitting 20 is close to or greater than that of the end cap 28 then the stress and strain induced in both the fitting 20 and the end cap 28 may be considered and analogous considerations apply representative sizes of an end cap fabricated from the currently preferred teflon u00ae pfa material and a stainless steel fitting will be will be used as an example teflon u00ae pfa is currently preferred because of its desirable high temperature properties teflon u00ae pfa can withstand relatively high temperatures without melting it will be appreciated however that other polymeric materials such as polypropylenes or polyesters could likewise be utilized thus there is no intention to limit the invention to the specific materials mentioned or.