SPRAY IRRIGATION. 



23 



•The chief advantage in the suspension system is the reduction of 

 )bstruction in the field, and where it is well constructed the plant will 

 je very durable. This type costs more than the others and is not as 

 •ommonly used as the simple post supports. The cleaning of nozzles 

 >n highly supported lines is difficult, so pipe should be kept within 

 •each. 



NOZZLE LINES. 



The pipe in the nozzle lines should be galvanized wrought iron or 

 ;teel. The galvanizing not only makes the system longer lived, but 

 •educes oxidation of the metal, which, if not prevented, tends to form 

 scales that fill the nozzles. 



A nozzle line is connected with the main feed pipe by means of a 

 *iser cut the proper length to act as the first post in the line. In the 

 longer lines it is well to have 

 ;he riser of H-inch pipe, which 

 vill make a strong support 

 iven if this is larger than the 

 irst section of nozzle line. An 

 ?lbow is placed on top of the 

 "iser, and into this is screwed 

 i long nipple which terminates 

 n a standard brass gate valve 

 (fig. 12). To reduce friction 

 ;his valve should be of the 

 same size as the standpipe. 

 rhe turning union is screwed 

 nto the opposite side of the 

 valve. The union most com- 

 nonly used contains a screen 

 for catching sediment from the 

 passing water. A capped handle 2 feet long, made of f -inch pipe, is 

 screwed into the side of the union. This serves as a lever for turn- 

 ing the nozzle line in its bearing as well as giving entrance to the 

 anion for flushing the screen. 



Reducing couplings, and not bushings, should be used for connect - 

 ng the different pipe sizes. A f-inch valve or a cap should be placed 

 aver the extreme end of the nozzle line. This permits flushing out 

 the line at any time bv opening the valve or removing the cap. 

 (See fig. 13.) 



Main Feed Pipes. 



There are several kinds of pipe adaptable for spray irrigation 

 mains — steel or wrought iron with threaded joints, riveted steel with 

 langed or bolted joints, cast iron with lead or bolted joints, and wood- 

 stave pipe. 



Fig. 15. — Anchorage for suspended overhead 

 nozzle lines, showing location of " dead- 

 man " and turnbuckles. 



