What this step adds; in part B, gas going to the stove and its flameParts already in placeA floating-drum plant of the Indian KVIC type, cut through its middle. Dung and water mixed 1 : 1 run down the inlet pipe into a brick digester 1.30–1.65 m across and 1.85 m deep in slurry; with no air, bacteria turn it into gas, which collects under a 1.5 m steel drum floating on a central guide pipe. The drum rises as it fills, and each day's feed pushes the same volume of digested slurry out to the pit, where it is used as fertiliser. The research notes behind this guide give no sourced biogas figures, so every rate here is an assumption of the model, not a measurement: 40 kg of fresh cattle dung and 40 L of water a day, 40 days in the digester (3.2 m³ of slurry), 0.04 m³ of gas per kg of dung (1.6 m³ a day, made steadily), 60% methane, and 0.35 m³ an hour per burner ring. Methane gives about 35.8 MJ per m³, so a day's gas holds about 34 MJ of heat, about 2.3 hours of both rings. A floating drum stores its plan area times its rise: 1.77 m² × 0.7 m ≈ 1.24 m³. This is a guide to how the parts go together, not engineering drawings. Biogas is flammable and contains poisonous hydrogen sulphide: keep the drum, hose and joints airtight, find leaks with soapy water, never with a flame, and never climb into a digester or slurry pit, even an empty one: the gas left in it can kill you.