Abstract: A device for the setting and automatic regulation of the mixture ratio of a gas/air mixture for industrial furnaces comprises two coaxially-arranged diaphragm pressure gauges, connected in opposition, via a ratio setting mechanism, for the gas and the air, and a throttle member, controlled by the diaphragm displacement, in the gas or the air feed pipe. The two diaphragm pressure meters each are oppositely acted upon on only one side by the gas pressure or the air pressure respectively. The throttle member is controlled directly by the diaphragms. The diaphragm pressure gauges and the ratio setting mechanism together with the throttle member are designed as a structural unit.