PVC Double Membrane covers are ideal as gas buffers and covers on tanks. A double membrane roof is a double cover where the outer membrane is always kept under pressure. As a result, rain, snow and wind have little effect on it. The inner membrane holds the gas into the tank. The cover has the major advantage of a large variable gas collection capacity and can serve as a cover for a digester or post-digester, to temporarily collect gas. Naturally, a double membrane roof complies with European environmental legislation. Depending on the chemical composition of the liquid and height of the tank wall, the required center column can be applied in either hardwood or a stainless steel version. Thanks to highly chemically resistant and mechanically strong foils, the double membrane cover meets the highest quality standards. New cutting and welding procedures improve the absorption of biaxonal forces in the covers. The hemispherical construction provides a low wall load. The PVC double membrane covers are provided including blower.