From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Proposal for testing and comparing the performance of different water pumps with hot water to investigate flow fall-off at higher temperatures.
| Identifier | ExFiles\Box 149a\1\ scan0023 | |
| Date | 5th June 1930 | |
| Es. (2 copies.) c. R.{Sir Henry Royce} Sg.{Arthur F. Sidgreaves - MD} Mor. c. E.{Mr Elliott - Chief Engineer} F.{Mr Friese} By.{R.W. Bailey - Chief Engineer} c. Lr.{Mr Ellor} c. Mr. Jaques. A.I.D. X7150 WATER PUMPS. PERFORMANCE WITH HOT WATER. Plotting pump inlet depressions measured on the Meccano Hangar against temperature at the same point shows us that the 'F' water pump can only create about half the suction with hot water that it ought to be able to create. The consequence of this is that the fall off in water flow with increasing temperature is greater and starts sooner than it need. We believe this indicates bad conditions in the inlet to the pump rotor, and would like some tests done to compare available pumps. When the water is heated up and flow commences to fall, it is thought that vapour cavities form in the pump presumably behind the blades at inlet. If the depression behind the blades is much lower than in the inlet pipe to the pump, due to throttling or to too sudden acceleration of the water, then flow will commence to fall off earlier than it should, i.e. earlier than we should expect from the vapour pressure of water at that temperature. We suggest the following three pumps be compared with water at various temperatures:- Standard 'F' Pump. Phantom II. Pump. Falcon III. Pump with double inlet. The pumps should be run at 3000 R.P.M., and taps fitted in the suction and delivery pipes. We suggest that the pump suctions be set at 1,2,3 and 4 lbs/sq. in., and the delivery pressure at 6 lbs.sq.in. with the water at 50°C. Then the water can merely be heated up without altering the taps, and readings taken every 5° of pump suction, delivery pressure and quantity flowing (measured with a half-gallon measure). The test results can be shown all on one sheet for each pump (3 sheets in all) plotted on a base of water temperature, °C. | ||