INDUSTRIAL FUMIGATION AGAINST INSECTS 53 



Preparation of the Mill. — The grain feeder or regulator above 

 the first break should be closed and the mill allowed to run. The 

 entire mill crew should be given rubber mallets and assigned the task 

 of hammering slide spouts, cleaning feed gates and suction lines, and 

 moving as much accumulated stock into the mill stream as possible. 



As soon as the rolls are opened after the feed has been shut off, 

 the elevator-boot slides should be pulled up and the accumulations of 

 milling stock pulled out of reach of the belt cups. 



The mill should be run for an additional 15 minutes to remove 

 as much milling stock as possible. 



After the mill has been shut down,, the roof vents from the cyclone 

 dust collectors should be tightly sealed. This is extremely important, 

 since the cyclone dust collectors are directly connected with almost all 

 machines. The best method is to remove the mushroom-shaped caps 

 and replace them with tightly fitting metal caps. Covering the 

 vents with paper or combinations of paper and burlap or tarpaulin 

 is not entirely satisfactory and is not recommended. 



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 of the purifiers should be 

 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 



