16 



BULLETIN 495, U. S. DEPARTMENT OF AGRICULTURE. 



permitting the use of longer laterals of smaller pipe. The sizes of 

 pipe must be so proportioned and the system so designed as to give 

 as nearly as possible a uniform pressure on all the nozzles within the 

 area to be irrigated at one time. The risers reach a height of 4 to 6 



0= — -CI = — =0 =C r Cte: 



oo o o= 



Gate Valves 



•^ — ~- — -p o o — r i i' i — ir 



=0 0= 



= = 000 



J T 3 ^- 



a a 



LATER A LS- 

 n o o ' =o =o 



■;■ *"■ — *•* r> r*- 



Dram Plugs 



Stands 



SO i O i o t > 



Fig. 9. — Typical plan for piping a field for stationary-nozzle spray systems, showing 

 staggered positions of nozzles to obtain the least amount of overlapping of spray. 

 Distances marked a should be equal. 



feet above the surface for truck and extend above the trees for 

 orchard irrigation and should be staggered, as shown in figure 9, to 

 reduce the overlapping of spray. 



Fig. 10. — Sketch showing typical fittings of underground laterals for stationary- 

 nozzle spray systems. A, Main feed pipe ; B, bushing at reduction of pipe sizes ; 

 O, cross in main feed pipe ; D, drain cock or plug ; II, sprinkler heads or nozzles ; 

 L, lateral pipe lines; M, malleable unions; N, nipples; 8, |-inch galvanized stand- 

 pipes; T, malleable tees; V, brass gate valves. 



The nozzles vary in design and generally are made of brass. 

 Those observed in the field by the writer may be classified in three 

 groups (fig. 11). First, solid nozzles with no movable parts; sec- 

 ond, adjustable nozzles with parts which can be manipulated to 

 change their capacity or form of spray; third, rotary nozzles which 



