The membrane separation of a silane, dichlorosilane, trichlorosilane, and tetrachlorosilane gas mixture has been theoretically and experimentally studied. The ideal separation factors have been determined experimentally and their values in the separation cell at pressures P (1) and P (2) have been found. The separation factor has been calculated for different ratios of flows in the compartments of a membrane module. The silane cleaning process for the removal of highly penetrating impurities in a radial membrane module and in a membrane module with a feed tank has been calculated.