Abstract: A gas control apparatus, designed primarily for sewage treatment plants, comprising a large central storage tank containing water with a fluid inlet and a fluid outlet, a gas inlet under pressure a gas flow unit containing in part a baffle with holes, a gas outlet, and a safety outlet venting to the atmosphere. By adjustment of the fluid outlet, a constant water level is maintained to provide constant back pressure. By adjustment of safety depth outlet, the pressure at which the gas is vented to atmosphere is controlled. Specifically, the gas control apparatus performs five functions: (1) limits back pressure, (2) acts as a flameback trap, (3) eliminates fluid vapor and other soluble impurities from the gas, (4) cools the gas to fluid temperature, and (5) protect system from high pressure caused by blockage either before or after the apparatus.