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).
Petrol pump performance tests, comparing delivery times at various temperatures using Pratt's Ethyl Petrol.
| Identifier | ExFiles\Box 149\4\ scan0015 | |
| Date | 2nd October 1936 | |
| -2- The pump was switched on and after 10 seconds wait the drains from the carburetter opened. It was observed that there was a delay of from 20 to 25 secs. till the petrol reached the pump, this time being more dependent on the temperature of the petrol than that of the pump, and there was a further delay till petrol free of vapour reached the carburetter, though it was impossible to get an accurate reading for this, the time for the first pint to be drawn off the carburetter being taken instead and compared with the ultimate steady delivery of the pump. Pratt's Ethyl Petrol. | Tank Temp. °C. | Temp. Pipe Line °C. | Under Bonnet Temp. °C. | Time to Reach Pump Secs. | 1st Pint Secs. | Steady Del. per Pint Secs. | |----------------|---------------------|--------------------------|--------------------------|----------------|--------------------------| | 30 | 32 | 75 | 29 | 60 | 48 | | 32 | 32 | 80 | 20 | 66 | 45 | | 32 | 50 | 80 | - | 86 | 52 | | 28 | 49 | 90 | Pumps failed to pick up. | | | The pump used in this test was that off 32-EX which had failed owing to temperature in France. Though identical tests with a new standard pump from production gave very similar results. Comparison was always difficult owing to the lighter fractions boiling out of the petrol in spite of it being frequently changed. Comparative tests between the EX.1 high lift pump and standard pump were also made, the time being taken for the first ½ pint, first pint, and ultimate steady delivery. See Graph No.1. This shows an increased delivery for the high lift pump, though it is only a small gain when taken over the first half pint delivered by the pump, namely, an increased flow of 9 pints, whereas at the steady delivery the increase is 34 pints per hour over the standard pump. It is during this period that the temporary starvation occurs; i.e., when the float chamber is emptied by the engine before the pump can deliver sufficient to refill and maintain it. | ||