A centrifugal influent pump is operating at 1,750 rpm. The pump curve (at 1,750 rpm) and the system curve are shown in the tables. The operator increases pump speed to 2,000 rpm using a VFD. Assume the system curve does not change and that points between table values can be linearly interpolated. Use the affinity laws: - Q₂/Q₁ = N₂/N₁ - H₂/H₁ = (N₂/N₁)² What is the expected NEW operating point (flow in MGD and head in ft) after the speed increase? Reference: 1 MGD = 694.4 gpm. (Extraneous data: motor nameplate is 60 hp; discharge pipe is 10-inch.)
| Flow (gpm) | Head (ft) |
|---|---|
| 0 | 70 |
| 300 | 62 |
| 500 | 52 |
| 600 | 45 |
| 700 | 36 |
| 800 | 25 |
| Flow (gpm) | Head (ft) |
|---|---|
| 0 | 12 |
| 300 | 20 |
| 500 | 32 |
| 600 | 45 |
| 700 | 54 |
| 800 | 66 |
| 900 | 81 |