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16 .
Schedule number of a pipe, which is a measure of its wall thickness, is given by
| A. | 1000 P'/S |
| B. | 100 P'/S |
| C. | 1000 S/P' |
| D. | 10000 P'/S |
17 .
The net positive suction head (NPSH) of a centrifugal pump is defined as the sum of the velocity head and the pressure head at the
| A. | discharge. |
| B. | suction. |
| C. | suction minus vapor pressure of the liquid at suction temperature. |
| D. | discharge minus vapor pressure of the liquid at the discharge temperature. |
18 .
With increasing flow rate, the hydraulic efficiency of a centrifugal pump
| A. | monotonically decreases. |
| B. | decreases and then increases. |
| C. | remains constant. |
| D. | increases and then decreases. |
19 .
In case of hydraulically smooth pipe, the resistance to flow depends only on the Reynolds number, whereas for a hydraulically rough pipe, the resistance to flow is governed by the relative roughness.
| A. | relative roughness. |
| B. | absolute roughness. |
| C. | friction co-efficient for flows at equal Reynold number. |
| D. | all (a), (b) & (c). |
20 .
Water hammer in a pipeline results from the
| A. | bursting of pipelines due to closure by a valve. |
| B. | rapid pressure change due to a rapid change in the rate of flow. |
| C. | pressure increase due to closure of a valve resulting in decrease in rate of flow. |
| D. | none of these. |
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