SPRAY IRRIGATION. 



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rusting of the metal. The idea was conceived of replacing the holes 

 with small brass nozzles which could be screwed into the pipe shell 

 and would not rust. It was also found that by placing one row 

 of nozzles in a pipe line which could be turned or rolled in bearings, 

 a strip of land 50 feet wide could be irrigated by turning the line of 

 nozzles to different positions through a total arc of about 90°. Spe- 

 cial turning unions containing screens have been patented for con- 

 necting the nozzle lines to the feeder system. Likewise there are drill- 

 ing machines for boring holes and tapping threads in the pipe for 

 the nozzles. Machines for turning the nozzle lines backward and 

 forward are being perfected and seem to be desirable for special con- 

 ditions where night irrigation is practiced or spray is used for frost 

 protection, as in Florida. 



Figure 12 shows an underground section of a main feed pipe in 

 the center of a field with connections to two nozzle lines, one on each 

 side of a farm road, as in the typical farm (fig. 1). 



Grade to drain back into Main 



FiG. 12. — Sketch showing typical fittings for overhead nozzle lines connected to main 

 feed pipe and method of crossing a farm road. A, Main feed pipe ; D, drain cock 

 or cap ; E, elbow ; F, handle for turning nozzle lines ; G, cap on handle ; J, side- 

 outlet tee ; K, concrete base for pipe post ; L, nozzle-line pipe ; A 7 , " long " nipples ; 

 P, pipe hanger ; Q, 1^-inch pipe post ; R, reducing cocket ; U, turning union ; T, 

 brass gate valve ; X, risers to nozzle lines ; Z, nozzles. 



LOCATION AND CONSTRUCTION OF OVERHEAD SPRAY SYSTEMS. 



Each overhead spray plant should be modeled to fit the field and 

 conditions under which it is to operate. Assuming that water sup- 

 ply has been developed, there are three major parts to any system 

 which should be considered in the order given. First, type and loca- 

 tion of nozzle lines; second, type and location of main feed pipe; 

 third, type and location of pumping plant. The nozzle lines should 

 take the direction most desirable to cultivate the field, so that the 

 crop rows will be parallel to the rows of supports. In general, noz- 

 zle lines should run perpendicular to the main feed pipe. The entire 

 field system should be designed to use the minimum amount of large 

 pipe, which generally means to run the main as straight as possible, 

 keeping the nozzle lines in sizes not to exceed 1^-inch pipe. 



The sizes of pipe to use in a nozzle line depends upon the length. 

 The end connecting with the feed pipe must be sufficiently large to 



