Abstract: A flushable device for capturing gas included within a produced-water stream is described. Gas and water pressure coordination is not required. Controls prevent liquid entry to the gas system and prevent gas entry into the water system. A gas/liquid separator receives an inner vessel lower end. A separator inlet receives a combined fluid stream. A liquid line passes into the inner vessel and down into the separator below the inlet so that liquid separated from the combined stream will flow up the liquid line. The gas line extends from the inner vessel upper end. The gas line conveys gas from the inner vessel upper end to a gas collection system. A top float in the inner vessel activates a gas line motor valve. A bottom float in the inner vessel activates the liquid line motor valve and a second gas vent for rapid expulsion of slugs of gas.