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<br />% Figure 14-10 North Decline Mine Discharge System <br />i. <br />Flow Calculation <br />Determine the pipe size for the North Decline Mine discharge pipe assuming a steel pipe and 350 gpm. <br />Reference Figure 14-8 for piping arrangement. <br />Flow through a pipe is determined by the amount of head causing flow and the head loss in the pipe <br />resisting flow. Flow rates are calculated by trial and error by varying the pipe size so the head causing <br />flow equals or exceeds the head loss in the pipe system. Experience is used to assure the flow rate is <br />reasonable Tor the pipe size. <br />Available Head <br />Elevation Maximum Pool <br />Elevation Flow line <br />Available Head Causing Flow <br />4760 Maximum desirable level in NW Intake Pool <br />4752 FD Discharge Pipe -,el5v~~a~ f~~S a7lfai N~~ <br />Design Flow <br />Pipe Diameter -Steel Pipe <br />Inside Diameter <br />Area <br />Velocity <br />Pipe Length <br />Mine to Elbow <br />Elbow -Equivalent Length <br />Total <br />Loss in oioe <br />Steel pipe C= <br />Entrance loss k(v^2)/2g <br />Friction loss in pipe = f <br />f = 0.2083(100/C)^1.85' q^1.85/d^4.8655 <br />Total Loss in pipe <br />Pipe Length <br />Elbow to Free SuHace under access road <br />Loss in pipe <br />350 gpm <br />8 inches <br />7.9 inches <br />0.340 SF <br />2.29 fUsec ~ ~j <br />170 v d <br />20 '~ /~ <br />190 / ~v <br />100 ~ <br />0.06 Feet ~/ <br />0.45 Feet'per 100 Feet <br />A.3~Feet~ q / ~ 90 Feet <br />200 <br />Steel Pipe C= 100 , <br />Friction loss in pipe = i <br />f = 0.2083(100/C)^1.85' q^1.65/d^4.8655 0.43 Feet per 100 Feet <br />Total Loss in pipe 0.86 Feet 200 Feet <br />Conclusion: <br />Head loss in pipe from mine to elbow is much less than the available head. <br />Therefore an 8-inch diameter steel pipe will handle the 350 gpm design flow. <br />Elbow to free surface drops 4 feet so there is no effective head loss. <br />Therefore a 8-inch diameter steel pipe will handle the 350 gpm design slow. <br />PVC pipe may be utilized. PVC pipe has less friction loss than steel <br />pipe so its capacity would be greater. <br />01 /01 <br />