When the weapons fire, the servants are equipped with gas mask connected to the air duct, because the rate of carbon monoxide is dangerous. This duct is connected to the filter and ventilator which are situated in the shell-proof rest chamber, those ensure the renewal and treatment of the ambient air.
Thanks to the sas tight metal panels (a horizontal panel and a vertical one) which are situated between the shell-proof combat compartment and the shell-proof rest chamber, the air is maintained at an overpressure, regarding to this of the shell-proof combat compartment.
Goal: to chase out the flue gas, harmful fumes and to prevent the penetration of toxic combat gases.