INDUSTRIAL FUMIGATION AGAINST INSECTS 



19 



«*g* 



tendency to rust and cause clogging of the spray nozzles, it is rarely 

 used. Either brass or copper tubing is recommended. A flexible 

 copper tubing three-eighths inch in diameter (fig. 20) costs about 6 

 cents a foot. Since it can be readily bent, elbow fittings are unneces- 

 sary, and compression couplings can be used, except at the main 

 inlet, where the cylinders are connected. 



In large buildings, where there are several floors and numerous 

 branch lines must be used, each floor should be provided with a 

 separate riser, which 

 should be of larger 

 tubing. A spray 

 nozzle (fig. 21) 

 should be provided 

 for every 15,000 to 

 25,000 cubic feet of 

 space. It is custo- 

 mary to use from 10 

 to 18 nozzles to a 

 riser, but the latter 

 number should not 

 be exceeded. 



Most buildings can 

 be piped with copper 

 tubing at a cost of 

 about 10 to 13 cents 

 per 1,000 cubic feet 

 of space. Brass tub- 

 ing costs about two 

 and one-half times as 

 much as copper. 



The piping system. 

 should be so ar- 

 ranged that the gas 

 pressure will be ap- 

 proximately the same 

 at all nozzles, thus 

 insuring an even dis- 

 tribution. Each riser is connected to a special inlet pipe leading 

 through the outside wall of the building to the cylinders of gas. Pip- 

 ing plans are usually made by the fumigating company after it has 

 made a survey of the building. Should blueprints or rough sketches 

 and measurements be forwarded for making piping plans, special 

 attention should be given to offsets and whole or part partitions. 

 Any other special conditions, such as heavily infested machinery, 

 rows of packing machines, or other places of heavy infestation, 

 should be noted in order that an extra nozzle may be added if it is 

 thought desirable. 



Applying the Gas 



Each cylinder of liquid hydrocyanic acid is supplied with an inlet 

 valve and an outlet valve. The outlet valve is attached to a steel 

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



Figure 20. — Installation of %-inch copper piping for in- 

 troduction of liquid hydrocyanic acid. This piping, being 

 flexible and easily cut with a saw, as: indicated, can be 

 run along side walls and out along rafters, or to any 

 point where it seems best to install the spray nozzles. 



