52 CIRCULAR 369, U. S. DEPT. OF AGRICULTURE 



Sifter sections should be removed, the stock on the sieves deposited 

 on the floor, and the sieves replaced. The doors in sifter sections 

 should be replaced, but not tightly enough to prevent free circulation 

 of the gas. 



Accumulations behind the feed gates of the purifiers should be 

 removed, and the feed gates tied or blocked open to allow free 

 passage of the gas into the slide spout carrying stock to the purifier. 



Dividing gates below the cant boards of both reels and purifiers 

 should be exactly vertical to allow equal distribution of the gas into 

 the different conveyors. Stock in the end of these conveyors beyond 

 the reach of the flights should be removed, together with any packed 

 accumulations more than 3 inches deep. 



Accumulations above the feed gates on the rolls should be re- 

 moved. The roll housings should be cleaned and the feeder gates 

 blocked open to allow the gas to reach the feeder-gate roll housing 

 and slide spouts above. 



Where Buckley grinders are used, the hand lever should be raised, 

 thus compressing the driving spring and separating the grinding 

 surfaces to allow free passage of the gas through the mechanism. 



The final operation should consist of checking all units to see that 

 all machines are closed. Accumulations removed from elevator boots 

 or other machinery should be cleaned up, bagged, and placed in a 

 fumigation or heating vault for treatment. 



Windows and doors should be closed but need not be sealed. 

 Broken sash should be replaced. 



Testing the fumigation lines. — Air pressure should be applied to 

 the piping system, and each spray nozzle examined to see that it is 

 working properly. Leaky connections can be detected and tightened. 



Application of the gas. — The liquid hydrocyanic acid is forced 

 into the various lines at the rate of 6 to 8 ounces for each spray nozzle 

 on the line. The standard hydrocyanic acid cylinder has too small an 

 opening to allow the gas to be put into the fumigation lines with 

 sufficient pressure to insure uniform distribution. A special appli- 

 cator is therefore utilized, which consists of a small steel tank hold- 

 ing 35 pounds of liquid hydrocyanic acid and capable of withstand- 

 ing a working pressure of 200 pounds. A gas-outlet valve on the 

 top-central part of the cylinder is connected with a half -inch copper 

 tube extending to the bottom of the tank. This tube is larger than 

 that of the shipping cylinder and allows the more rapid flow of gas 

 needed. Gas-inlet valves (half -inch brass) and a pressure gage are 

 also located on the top-central part of the cylinder. From the tank 

 connection of the gage a bypass of quarter-inch copper tubing sup- 

 plied with a valve is connected to the gas-outlet line between the 

 outlet valve and the manifold of the piping system of the building 

 being fumigated. This bypass allows the pressure developed by the 

 transfer of the hydrocyanic acid from the shipping cylinder to the 

 applicator to escape into the manifold, thus facilitating the filling of 

 the applicator. 



Chloropicrin as a Mill Fumigaxt 



For fumigation with chloropicrin the mill should be prepared in 

 the same way as for fumigation with hydrocyanic acid, except that 

 items 1 to 14 of the directions for preparing the mill after the ma- 



