dioxide to separate and concentrate the precipitates during such processing the clean gaseous carbon dioxide is directed to a condenser where it is reliquified and then returned to the storage tank 18 the liquified carbon dioxide is circulated through the apparatus by the pump 16 for removing wash bath vapors from the cleaning vessel 12 a compressor 24 is provided to pump gaseous carbon dioxide from the cleaning vessel 12 to a condenser 27 where it is condensed back into liquid phase and then redirected to the storage tank 18 the gaseous carbon dioxide typically is evacuated from the cleaning vessel 12 and directed to the condenser 27 during the washing and rinse cycles and upon completion of the washing operation prior to opening the cleaning vessel 12 and removing the cleaned items in order to control the pressure and temperature within the cleaning vessel 12 carbon dioxide may be quickly discharged from the cleaning vessel 12 to the purge tank 28 without the need for the compressor 24 moreover the purge tank 28 also provides a source of low pressure gaseous carbon dioxide which can be used to purge the cleaning vessel 12 of air before the wash cycle.