740 HYDRAULICS AND ITS APPLICATIONS 



(2) If in the preceding question the pressure at the station is 1,120 Ibs. 

 per square inch, determine the efficiency of transmission, and also, taking 

 / = '01, the length of the supply pipe line. 



Answer. Efficiency = 89'2 per cent. 

 Length = 4*7 miles. 



(3) 100 B.H.P. is required from a hydraulic motor having an efficiency 

 of 75 per cent. The motor is two miles from the generating station and 

 only a single 6-inch pipe line is available. The pressure at the station 

 being 1,120 Ibs. per square inch, determine the pressure at the motor, the 

 efficiency of transmission, and the velocity of flow. 



Answer. Pressure = 1,088 Ibs. per sq. inch. 

 Efficiency = 97'0 per cent. 

 Veloc% = 2-392 f.s. 



(4) Two. branch pipes, respectively 4 inches and 3 inches diameter, are 

 supplied from a 6-inch pipe. The pressure at the delivery end of the 

 4-inch pipe is 700 Ibs. per square inch ; that at the end of the 3-inch pipe 

 is 710 Ibs. per square inch. These pipes are respectively 500 and 700 

 feet long. The 6-inch pipe is 880 feet long. Take / throughout as being 

 = '01 and determine the pressure at the inlet to the latter pipe. 



(5) Determine the maximum H.P. which can be transmitted through a 

 4-inch pipe two miles long/ = '012 if the inlet pressure = 750 Ibs. 

 per square inch. Also determine the pressure at the outlet, and the 

 velocity of flow when this power is being transmitted. 



Answer. 56'4 H.P. 

 Pressure = 500 Ibs. per square inch. 

 Velocity = 4*94 feet per second. 



(6) An accumulator has an 18-inch ram and 23 feet lift, and is loaded 

 with 129 tons total weight. Taking friction to account for '25 per cent, of 

 the total pressure on the ram, determine the H.P. given into the mains if 

 the accumulator falls steadily in three minutes, the pumps delivering 500 

 gallons per minute in the meantime. 



Answer. Total H.P. = 67 + 396 = 463. 



(7) A steam accumulator is placed horizontally and has a 48-inch 

 steam piston coupled to a 6-inch ram. The steam piston packings, etc., 

 exert a frictional force of 500 Ibs., while the hydraulic packings account 

 for 1 per cent, of the total pressure exerted oil the ram. Determine this 

 pressure if the steam pressure is 150 Ibs. per square inch. 



Answer. 9,486 Ibs. per square inch. 





