A method for extinguishing tank fires for extinguishing petroleum fires, in which a gas or dispersion gas fire extinguishing mixture is fed into the fire zone from in internal fire extinguishing device (injector) via a tripping and shutoff device, a discharge line, and a circular spray nozzle, characterized in that said fire extinguishing mixture is supplied from a float-type circular spray nozzle that pops up above the surface of the burning liquid, and the fire extinguishing is performed in three steps: 1st step: the float-type circular spray nozzle, communicating with the injector by means of a pipeline via the tripping and shutoff device is located below the layer of the flammable liquid at a depth equivalent to at least the height of the circular spray nozzle and/or is located on the surface of said liquid, and the length of the pipeline is defined by the following ratio: L R = R 2 T + H bF − H lnj − H Düse 2 wherein L R is the length of the pipeline in meters, R T is the tank radius in meters, H bF is the maximum fill height of the flammable liquid in the tank in meters, H Inj is the entry height of the discharge line from the injector into the tank in meters, and H Düse is the height of the circular spray nozzle in meters; 2nd step: after a signal from the fire alarm, the tripping and shutoff device is opened at the injector, and said fire extinguishing mixture is fed via the pipeline and the float-type circular spray nozzle beneath the layer and/or onto the sur face of the flammable fluid in closed streams from the center point to the edge parallel to the surface, specifically with a deflection of 360 degrees; in the process, 0.05-0.2 parts of said fire extinguishing mixture is atomized at an angle of 3 to 90° to the surface of the liquid; 3rd step: it is ensured that the float-type circular spray nozzle pops up above the burning surface by a height of 0.005 D T to 0.05 D T (where D T stands for the tank diameter); in the process, the fire extinguishing mixture is fed at a flow rate of at least 0.15 kg/sec·m 2 with a circular deflection of the streams, and the number of streams is determined as follows: 90 ° α ≤ n ≤ 360 ° α in which n stands for the number of streams and α stands for the stream divergence angle. 1st step: the float-type circular spray nozzle, communicating with the injector by means of a pipeline via the tripping and shutoff device is located below the layer of the flammable liquid at a depth equivalent to at least the height of the circular spray nozzle and/or is located on the surface of said liquid, and the length of the pipeline is defined by the following ratio: L R = R 2 T + H bF − H lnj − H Düse 2 wherein L R is the length of the pipeline in meters, R T is the tank radius in meters, H bF is the maximum fill height of the flammable liquid in the tank in meters, H Inj is the entry height of the discharge line from the injector into the tank in meters, and H Düse is the height of the circular spray nozzle in meters; L R is the length of the pipeline in meters, R T is the tank radius in meters, H bF is the maximum fill height of the flammable liquid in the tank in meters, H Inj is the entry height of the discharge line from the injector into the tank in meters, and H Düse is the height of the circular spray nozzle in meters; 2nd step: after a signal from the fire alarm, the tripping and shutoff device is opened at the injector, and said fire extinguishing mixture is fed via the pipeline and the float-type circular spray nozzle beneath the layer and/or onto the sur face of the flammable fluid in closed streams from the center point to the edge parallel to the surface, specifically with a deflection of 360 degrees; in the process, 0.05-0.2 parts of said fire extinguishing mixture is atomized at an angle of 3 to 90° to the surface of the liquid; 3rd step: it is ensured that the float-type circular spray nozzle pops up above the burning surface by a height of 0.005 D T to 0.05 D T (where D T stands for the tank diameter); in the process, the fire extinguishing mixture is fed at a flow rate of at least 0.15 kg/sec·m 2 with a circular deflection of the streams, and the number of streams is determined as follows: 90 ° α ≤ n ≤ 360 ° α in which n stands for the number of streams and α stands for the stream divergence angle. n stands for the number of streams and α stands for the stream divergence angle.