WATER FIGURES 



493 



Friction-head in feet in clean wrought-iron pipe for each 100 feet of length 

 when discharging various quantities of water from a windmill (Fuller) 



If the water is to be carried some distance fom the pump to a res- 

 ervoir in the use of windmills in irrigation, then the pipe-line convey- 

 ing the water to the reservoir will offer friction to the flow, and this 

 friction expressed in feet should be added in determining the total 

 head against which the pump must operate. 



Suppose, it is desired to deliver 60 gallons of water per minute 

 through a pipe-line 100 feet long. The table shows that a 3-inch 

 line delivers 50 gallons per minute at a loss of 0.8 foot head, and a 

 4-inch line 75 gallons per minute with 0.48-foot loss. The size 

 desired is therefore between 3 and 4 inches, and as no intermediate 

 size is made in wrought-iron pipe, the 4-inch pipe is best, and the 

 total head to pump against would be 25 + 3 + 0.48, or a total of 

 28.48 feet. 



