Answer Happy

2. 20 marks: A centrifugal pump is located 15 meters above the surface of a tank that is filled with a hydrocarbon. The tank is open to the atmosphere and maintained at 25 deg C. The density of hydrocarbon is 900 kg/m3, while the vapour pressure of this hydrocarbon at 25 deg C is 4.5 kPa. Can you prove that this pump cannot pump the hydrocarbon even if it is fully primed?
After examining the pump curve and data from the supplier, you have found that the NPSH min for this pump is 0.65 m of water. If the suction pipe has a diameter of 2.50 cm, determine the max height at which the pump can be located without the risk of cavitation. The hydrocarbon flow rate is 2 L/s. a 1 Hints and notes 1: Typically, the NPSH min given by the supplier is always in meters of water. This is because water is the standard testing fluid. However, in this example, the fluid flowing is toluene. So minimum NPSH needs to be converted for toluene. NPSH toluene = NPSH water * (density water/density toluene). 2: The friction factor can be calculated from an empirical equation f = 0.3168 Re-0.25