. Control of insects in stored and manufactured tobacco. Tobacco Diseases and pests Control; Tobacco Storage Diseases and injuries. CONTROL OF INSECTS IN TOBACCO 27 EQUIPMENT AND PROCEDURE Vacuum fumigation equipment consists of a pair of steel chambers strong enough to withstand considerable pressure, a pump of suit- able size to evacuate the chambers, a volatilizer for the fumigant (for use in cool weather), and recording gages. Loading platforms and conveyors facilitate the handling of the tobacco. The chambers vary widely in size, most of those in commercial use ranging from 400 to 3,000 c
. Control of insects in stored and manufactured tobacco. Tobacco Diseases and pests Control; Tobacco Storage Diseases and injuries. CONTROL OF INSECTS IN TOBACCO 27 EQUIPMENT AND PROCEDURE Vacuum fumigation equipment consists of a pair of steel chambers strong enough to withstand considerable pressure, a pump of suit- able size to evacuate the chambers, a volatilizer for the fumigant (for use in cool weather), and recording gages. Loading platforms and conveyors facilitate the handling of the tobacco. The chambers vary widely in size, most of those in commercial use ranging from 400 to 3,000 cubic feet. In some of the larger units each chamber has a capacity of more than 30 hogsheads. The tobacco to be fumigated is placed in the vacuum chamber, the door is closed, and the air is pumped out until a vacuum of 28 to 29 inches is registered on a standard mercury gage (fig. 20). The degree of vacuum obtainable varies from day to day with the barometric pres- sure, but any vacuum of more than 28 inches is usually satisfactory. The proper dosage of fumigant is determined by weighing. The cylin- der or drum of fumigant is placed on a platform scales and connected to the intake line of the chamber. When a valve is opened the gas is sucked into the chamber and drawn all through the tobacco by the vacuum. At the end of the exposure period the gas is pumped out of the chamber and vented above the roof of the building. Air is then admitted to restore normal pressure in the chamber. This air is ex- hausted by pumping and air is again admitted. This procedure— called air washing—is usually performed twice with each lot of tobacco. The manufacturers of vacuum-fumigation equipment can supply estimates and specifications to meet the needs of individual factories or warehouse Figure 20.—Vacuum chambers for fumigating Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and ap
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