THE FLOW OF WATEK IN CONCRETE PIPE. 



17 



Stuffing Box, (fibre) 

 If far from end of pipq tube like #»'s m "^j!^j 



' %Zholes ~ / z'j r>side ah ^SL 

 ^ifijf near end rfpipe,tube fiAe-J^jf. 



/J-*- 75 6a£e. 



Sloffin, 



% I.Rnipple, popped. 



DETERMINATION OF LOST HEAD. 



The exact amount of ft f (fig. 1) must be determined. Where a 

 water column is used, say at gauge No. 2, the elevation JE^ is the 

 gauge reading added to the elevation of the gauge zero above an 

 assumed datum, with proper corrections (see p. 5). Where a 

 mercury manometer of the U-tube pattern is used, the reasoning is 

 as follows: It is desired to know the elevation E x (fig. 1) for a water 

 column which is the equivalent of a mercury column in a U-tube 

 placed as for gauge No. 1. 

 Referring to figure 2, the 

 mercury in the two legs of 

 the U-tube below Q will 

 beseen to balance. There- 

 fore the pressure of the 

 water at Q is just balanced 

 by the -column of mercury 

 *QT. But the pressure at 

 c equals that at d. If the 

 mercury X were replaced 

 with water it would reach 

 an elevation sR above Q, 

 where s is the specific 

 gravity of the particular 

 mercury in the gauge, 

 compared with the par- 

 ticular water in the pipe. 

 But the elevation to which 

 this water column would 

 reach is the desired eleva- 

 tion, E x . As applied to 

 these experiments, refer- 

 ring to figures 1 and 2, the 

 difference in elevation be- 

 tween the readings of the 

 low gauge and the high 

 gauge multiplied by the 

 specific gravity of the mercury and added to the elevation of the 

 low-gauge readings gave the elevation of the equivalent water 

 column when the proper corrections had been applied. 



MEASUREMENT OF MEAN VELOCITY. 



As a rule, each pipe tested presented its own problem as to the 

 method to be adopted to determine the mean velocity of the water, 

 and in case this method digressed from one of the following standard 

 methods it is described. 



164725°— 20— Bull. 852 2 



r? ij.- stop cock. 3/i' 



■ ^'woshers.threodedW*-- %^W.I. Pipe, lO"long, 

 -■ ; threaded. J 



Set flush with surfcce."\~Cap, tvith /£." ' diam. 

 i ho/g in centra, 

 t^rouf: — 



Note; In abore figures the piezometers are relat/'vely farffe. 



Fig. 3. — Various arrangements of piezometers for securing 

 pressure head at a given place on the pipe line. 



