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CIRCULAR 3 6 9, U. S. DEPARTMENT OF AGRICULTURE 



connected with the bottom of the cylinder. The inlet valve leads 

 directly into the top of the cylinder. A check valve should be installed 

 between the inlet valve and the compressor (figs. 15 and 16) to pre- 

 vent the gas from being forced back into the tubing leading to the 

 compressor, in case of trouble. The outlet valve, which has previously 

 been connected with the inlet pipe to the building, is then opened and 

 the gas is forced in. The pressure must be maintained until the liquid 



Figure 18. — Various attachments for spray nozzles used in fumigating a ware- 

 house, mill, or factory with liquid hydrocyanic acid. 



is blown through the pipes into the space to be fumigated. As soon 

 as the required quantity of liquid hydrocyanic acid has been forced 

 into the building, the pipe lines are blown clear and the inlet tubes 

 capped. The time needed to pump the contents of a 75-pound cylinder 

 into a building is approximately 7 minutes. 



SAFETY PRECAUTIONS 



At the conclusion of the fumigation and after the building has been 

 well ventilated, the spray nozzles should be removed and cleaned for 



