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Pump Experimental
The first 'real' department that I worked in after the induction course was Pump Experimental. This was where new designs of pumps were tested and evaluated. The project that was underway during my time there was the testing of the River Idle scale model axial flow pump. This was a 1/6 scale model of a 96" pump of which two were to be commissioned by Severn-Trent Water Authority for pumping flood water from the Idle to the Trent. There were to be two smaller 60" pumps to the same design. Having two pumps of each size gave eight pumping capacities from 5 m3/s to 35 m3/s.
| 96" pump | 60" pump | |
|---|---|---|
| Flow rate | 12.786m3/s 168750g/min | 4.972m3/s 65625g/min |
| Head | 3.96m 13ft | 3.96m 13ft |
| Motor | 1060kW 1500rpm | 450kW 333rpm |
An announcement of the contract was published in Water Services magazine in July 1976.
For this project, the daily routine in Experimental was to run tests on the 16" scale model pump and take readings of head, speed and torque for various flow rates. Other parameters such as power consumed and efficiency could be calculated from these values. From the speed and torque, the brake horse-power could be calculated. From the flow and head, the pump's 'water horse-power' can be calculated. Finally, the all important efficiency figure could be calculated by dividing the water horse-power by the brake horse-power. The various figures would be plotted and compared with the performance of previous tests. The objective was to meet the design criteria for head and flow at the highest efficiency possible by modifying the design of the impeller and the suction bell. The designers would review the performance figures and suggest improvements. The impeller and suction bell would be removed, re-machined or adjusted and then re-assembled for the next test. A key objective was to minimise the clearance between the impeller and suction bell while avoiding any contact during start-up and when running.
Another project was the thermal shock testing of a pump to establish its suitability for high-temperature duty. The easiest way to run the pump up to temperature was to run it in a closed loop of pipework and to let the losses heat up the water. Once it was at a constant temperature, the flow of water was switched to cold so that the effects could be noted.
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