Our high-frequency welded double membranes
Our double membranes are made of a PVC-coated polyester fabric that was specifically designed and produced for use in the biogas sector. The material is flame retardant in accordance with DIN 4102 B1 and it is UV-resistant. We use materials with a grammage ranging from 800 g/m² to 1,500 g/m². Our standard colours for this are agate grey as per TRAS-120 (similar to RAL 7038) or moss green (similar to RAL 6005), but other colours are also available on request, such as silver grey (similar to RAL 7001). The gas permeability of the membranes ranges from <200 cm³/(m² d bar) to <500 cm³/(m² d bar).
The material is welded together in our two factories in Düren using the high-frequency welding method. The outer membrane has built-in air inlets and outlets and condensate drain plugs. Hemstitch seams or flaps are worked into the inner membrane as guides for the fill level measuring equipment. If desired or depending on individual needs, we can also integrate viewing windows, service platforms or other built-in parts in our double membranes. For profiles up to the size of the hemisphere, we employ parallel cutting with material webs arranged in parallel to prevent concentrations of tension in the pole area.
Double membranes for bolted fastening systems feature a reinforced piping edge to guarantee the best possible durability at the clamping edge even under unusually high pressure or extreme weather conditions.