800 APPENDIX III 



or volume is not usually available; the former is limited to laboratory use, 

 which is outside the scope of this code. The bulk method is applicable 

 only when there is available a reservoir of regular form, the volume of which 

 up to various water levels may be accurately measured, and when the fol- 

 lowing conditions may be observed: 



The draw-down or filling of the reservoir must not cause a variation 

 in head on the turbine during a run exceeding the limits specified under 

 section 4 (6), namely, a total of 4 per cent of the head. It must be possible 

 to shut off completely all inflow into or outflow from the reservoir. The 

 tightness of the gates and reservoir walls must be tested by closing all gates, 

 and observing over a time of several hours the rate of rise or fall of water 

 level in the reservoir throughout the full range of variation of level which 

 will be used in the turbine test. At the same time any leakage through 

 the turbine head gates is to be measured. The surface elevation in the 

 reservoir is not to be so affected by velocity or wind effects as to cause local 

 variations in level of more than 5 per cent of the total draw-down used in 

 the turbine tests. This variation is to be observed by gauges distributed over 

 the whole reservoir, which are to be read simultaneously at short intervals 

 throughout the test. The effect of surface evaporation shall be investigated 

 and corrections applied to cover it. when local conditions are such that it 

 becomes appreciable. 



(6) By Venturi Meter. When it is possible to install a Venturi meter 

 not exceeding in dimensions or differing in conditions from meters whose 

 coefficients have previously been determined in accurate tests, the Venturi 

 meter may be used. The meter shall be similar in proportions to meter 

 previously tested. 



(c) By Color Velocity Method. When the water used by the turbine 

 passes through a conduit suited to the purpose, the color method of quantity 

 determination may be used, depending upon the time of passage between 

 two points of a mass of color injected into the stream. The distance between 

 the two points where the passage of the color is observed must be sufficiently 

 great to render the interval between the times of passage of the color at 

 the two stations large compared to the time required for all the color to pass 

 either station. The conduit must be of sufficiently regular form to per- 

 mit its cross-sectional areas to be accurately measured at all points between 

 the stations. 



(d) By Brine Velocity Method. A method similar to 11 (c) adapted to 

 closed conduits has been used, consisting in the injection of a mass of brine, 

 the time of passage of which is detected by the variation in electrical resist- 

 ance between two contacts placed in the stream. A pair of such contacts 

 is placed at each station, and the time of passage of the brine between the 

 stations is chronographically recorded by a specially arranged wattmeter. 

 The stations should be arranged as under 11 (c). 



(e) By Color Density Method. The coloration or color density may also 

 be employed for approximate tests, this method depending on the use of 

 a colored dosing solution in place of a salt solution in a manner similar to 

 the chemical method of 9 (e), observation of the color density replacing 

 the titration. 



