Abstract

Process and apparatus for protecting or preserving stored commodities, in particular bulk commodities such as agricultural produce, e.g. grain, against deterioration by pest action, comprising the introduction into and maintenance in the commodity in a substantially gas-tight enclosure of a pesticidal atmosphere comprising carbon dioxide. The carbon dioxide is admitted to the bottom of the storage space so slowly that it spreads out as evenly as possible in the bottom region, being mixed as little as possible with the air or like gas originally contained in the storage space and then displacing that air or gas progressively in an upward direction, to be vented to the atmosphere from the top of the space until the space is filled entirely with carbon dioxide in a predetermined concentration range. This range can be monitored and regulated automatically. Excess gas is vented through vent pipes, a slight back pressure being created by non-return flaps or throttles.