Abstract: An installation for the treatment of objects in a defined gas atmosphere whose oxygen content is smaller than that of air and with which environmentally damaging treatment gases are produced with a housing with an entry opening and with an exit opening for the objects passing through, conveyed through the housing, with a first treatment zone in the housing, which comprises the entry opening and which produces the treatment gas for the production of a process gas atmosphere, with a second treatment zone which is connected to the exit opening and which is connected to the first treatment zone via a passage opening for the objects and in which the atmosphere is lean of treatment gas and oxygen, with a circulation for the process gas with which a ventilator suctions process gas from the first treatment zone and sends it via a filter device which holds back the treatment gas, with a first sluice which is allocated to the entry opening and which is flowed upon by the purified process gas coming from the filter