A wastewater lift station runs one centrifugal pump. The pump curve and system curve data are shown in the tables. SCADA shows the station is currently pumping 0.72 MGD. 1) Use the tables to determine the operating point (flow and TDH). 2) Calculate the pump brake horsepower (BHP) at the operating point using: BHP = (Q(gpm) × TDH(ft)) ÷ (3960 × pump efficiency as a decimal). 3) Select the smallest STANDARD motor size that will handle the load when the motor service factor (SF) is 1.15. Assumptions/notes: Water SG = 1.0. Pump efficiency at the operating point = 70%. 1 MGD = 694.4 gpm. A motor can provide up to (nameplate HP × SF) before exceeding its service factor rating. Available standard motor sizes: 1, 1.5, 2, 3, 5, 7.5, 10 HP. (Motor voltage and motor efficiency are not needed.)
| Flow (gpm) | Head (ft) |
|---|---|
| 300 | 60 |
| 400 | 54 |
| 500 | 46 |
| 600 | 36 |
| 700 | 24 |
| 800 | 10 |
| Flow (gpm) | Head (ft) |
|---|---|
| 300 | 30 |
| 400 | 38 |
| 500 | 46 |
| 600 | 56 |
| 700 | 68 |
| 800 | 82 |