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A centrifugal pump running at 500 rpm and at its maximum efficiency is delivering a head of 30 m at a flow rate of 60 liters per minute. If the rpm is changed to 1000, then the head H in meters and flow rate Q in liters per minute at maximum efficiency are estimated to be
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- H = 60, Q = 120
- H = 120, Q= 120
- H = 60, Q = 480
- H = 120, Q = 30
Correct Option: B
N1 = 500 rpm, H1 = 30 m Q1 = 60l/minute
N2 = 1000 rpm, H2 = ? Q2 = ?
| Since | = | ||
| DN1 | DN2 |
| ∴ H2 = |  |  | ² | |
| N1 |
| H1 = | | | ² | × 30 = 120 m | |
| 500 |
| = | ||
| D³N1 | D³N2 |
| ⇒ Q2 = | | | |
| N1 |
| Q1 = | | | ² | × 60 = 120 l/minute | |
| 500 |
