Orbinox UK Ltd Looking for high integrity field proven biogas isolation butterfly valve technology? THINK InterApp….. Biogas typically refers to a mixture of different gases produced by the breakdown of organic matter in the absence of oxygen. Biogas is primarily methane and carbon dioxide, and can have varying amounts of H2S, moisture and siloxanes present. The amount of H2S and moisture present, will dictate the liner material selection, critical to the valves performance, as the H2S can condense with water to form sulfuric acid. This batch of DESPONIA series butterfly valves is destined for an AD biogas application. The yellow lever denotes gas service, for ease of identification on site.