APPENDIX III 801 



(/) By Resistance of Salt Solution. A method which has been used ex- 

 perimentally is similar to the chemical method of 9 (e), except that the 

 amount of chemical (salt) in solution is determined by measurement of the 

 electrical resistance of the solution instead of by titration. Care is required 

 to guard against changes in resistance due to small temperature variations. 



12. Measurement of Water Horse-power in Plants Containing a Fall 

 Increaser. In case of an installation including a fall increaser or other 

 device utilizing an auxiliary flow for increasing the effective head, the fol- 

 lowing provisions shall be observed: In determining the efficiency of the 

 turbine proper, considered separately from the fall increaser, the fall increaser 

 shall be closed, and precautions shall be taken that no water except that 

 passing through the turbine shall enter the system between the points at 

 which the head is measured. 



In order to determine the performance of the combined hydraulic instal- 

 lation, including both turbine and fall increaser, the total water horse-power 

 shall be computed from the sum of the turbine discharge multiplied by the 

 head on the turbine, and the auxiliary discharge multiplied by the head on 

 the fall increaser. The head on the turbine shall be measured from a point 

 immediately in advance of the point of intake to the turbine proper, as above 

 provided, and the head on the fall increaser shall be measured from a point 

 immediately in advance of the intake gates of the increaser, the head in 

 each case being measured to a point below the junction of the two streams 

 at the outflow from the plant. For the computation of water horse-power 

 it will be necessary to determine the division of the total discharge between 

 the turbine and fall increaser. This may be done when practicable by 

 separately measuring the water admitted to the turbine during the operation 

 of the fall increaser. 



If, owing to the arrangement of the fall increaser, it is impracticable 

 to separate the water horse-power of the turbine from that of the fall increaser, 

 the gross efficiency of the combined installation may be determined by meas- 

 uring the combined total flow, and the total head from a point common 

 to the two flows before entering the plant to a point after they are reunited 

 below the final point of discharge. 



