22 



CIRCULAR 4: 



U. S. DEPARTMENT OF AGRICULTURE 



PREPARATION OF WAREHOUSES FOR FUMIGATION 



The infested warehouses (figs. 12 and 13) were equipped with the 

 standard i^-inch copper pipes and small disk spray nozzles for dis- 

 tributing the hydrocyanic- acid to all parts of the building. The 

 small copper pipes entered through a hole in the wall near a con- 

 venient door or platform and were attached to the wall or ceiling in 

 accordance with a plan to distribute the gas throughout the space to 

 be fumigated. One small disk-type spray nozzle was installed for 

 each 20.000 to 30,000 cubic feet of storage space. This system of 

 pipes and nozzles enabled the gas to be introduced into the ware- 

 houses from the outside = The warehouses were filled with hogsheads 

 of flue-cured tobacco which were stacked not over four hogsheads 

 high (fig. 14). and space was left between the rows for ventilation 













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Figure 12. — Closed tobacco-storage warehouse containing three stories and a basement. 

 This warehouse was fumigated periodically during 1932 for the control of the tobacco 



moth. 



and for the use of laborers in moving the hogsheads. The spray 

 nozzles were so placed that the hydrocyanic acid would spray into the 

 space between the rows of hogsheads. 



The most satisfactoy method of sealing ventilators was found to be 

 that of placing a piece of durable cardboard over the metal grate 

 and then fastening a piece of gasproof tar paper to the brick wall, 

 covering the entire ventilator. A thin strip of a good quality of 

 heavy wrapping paper was then pasted over the edges of the tar 

 paper to prevent them from warping from the heat of the sun. In 

 figure 15 is shown a sealed ventilator which was torn open and photo- 

 graphed to illustrate the details of the sealing. 



