98-Mar-B5 May 2016 Page 2 of 22 SECTION A CALCULATIVE QUESTIONS Show all steps in the calculations and state the units f

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98 Mar B5 May 2016 Page 2 Of 22 Section A Calculative Questions Show All Steps In The Calculations And State The Units F 1 (101.51 KiB) Viewed 37 times

98-Mar-B5 May 2016 Page 2 of 22 SECTION A CALCULATIVE QUESTIONS Show all steps in the calculations and state the units for all intermediate and final answers. QUESTION 1 PUMP POWER AND EFFICIENCY PARTI PUMP POWER REQUIREMENT 100 mm V, 2 1.5 m The diameters of the suction and discharge pipes of a pump are 150 mm and 100 mm, respectively. The discharge pressure is read by a gauge at a point 1.5 m above the centre line of the pump. and the suction pressure is read by a gauge 0.5 m I below the centre line. The pressure gauge reads a pressure of 150 of 150 kPa kPa and the suction gauge reads a vacuum of 30 kPa (negative gauge pressure) when gasoline having a specific gravity of 0.75 is pumped at the rate of 0.035 m/s. Calculate the electrical power required to pump the fluid if the pump efficiency is 75%. (5 marks) + 0.5 m 150 mm V, PART II HOMOLOGOUS PUMP SCALING A one tenth (1/10) scale model pump impeller with a diameter of 188 mm is tested in a test facility using water under the following conditions: Pump Speed Head Flow 3600 rev/min 39.6 m 0.085 m/s Under these conditions the model impeller was found to have an efficiency of 84%. A homologous prototype (with an impeller 10 times the diameter of the model and geometrically identical to it) is to be installed and operated under a head of 110 m while pumping water. Determine the following: (a) Speed at which the prototype pump would need to operate to ensure homologous conditions. (b) Flow rate of water through the pump under homologous conditions. (C) Power required to operate the pump assuming ideal conditions. (d) Efficiency anticipated under the above conditions. (5 marks) (10 marks)