Answer Happy

5. The reconfiguration necessitates a new pump to transfer thickened sludge from the current cylindrical sludge holding tank after the RDTs to the digesters. The max liquid level in the holding tank is 10 feet above the discharge connection and the pump empties the tank down to the elevation of the discharge connection (suction remains flooded - ignore suction lift). The vertical lift from the discharge connection to the top of the digester is 18 feet. The holding tank is 8 feet in diameter. The pump empties the tank approximately once per hour and takes approx. 22 minutes to empty the tank. The pump BEP is 150 gpm at 19 ft of Total Dynamic Head (TDH). The pump rate varies from 200 gpm to 140 gpm as the tank pumps down. The dynamic head at the average duty point is approximately 3 feet. Given the above information, sketch the pumping system diagram below and label the following: (8) A. Static head when tank full (give value in ft) B. Static head when tank empty (give value in ft) C. Pump duty point tank full D. Pump duty point tank empty E. Average Pump duty point - based on avg flow to achieve tank discharge in 30 mins - give flow rate in gpm and TDH F. Best Efficiency Point (BEP) G. Preferred Operating Range (POR) (upper and lower)