To increase the productivity of sintering machines, sinter quality and economy of the gaseous fuel, it is necessary to ensure the optimal mode of external heating of sintering charge layer. The effect of sintering machine vacuum chamber throttling under the ignition hearth on the gas-dynamic mode of charge ignition and sintering, including the quality of sinter, sintering machine productivity, gas consumption for the charge ignition and the possibility to control and manage the charge humidity were considered. It is shown, that throttling of the first vacuum chambers allows reduction in the fuel consumption, charge shrinkage, amount of air suction into the ignition hearth and gas-discharge duct of the sintering machine and improvement of the sinter quality. The effects of air rarefaction on charge layer surface temperature and sinter quality are provided. The structural variants of vacuum chamber throttling implemented in practice are presented; two of them operate at sintering machines at Bhilai Iron and Steel Works, India. It is shown that throttling of the first vacuum chambers located under ignition hearth is effective for charge ignition and sintering processes in all cases and should be obligatory during the sinter production.