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).
Analysis of a petrol pump's performance, delivery rates, and its interaction with an air compressor and carburetter.
| Identifier | ExFiles\Box 61\3\ scan0281 | |
| Date | 30th October 1931 | |
| -3- Hs{Lord Ernest Hives - Chair}/Aln.8/KT.30.10.31. contd by the action of the regulator valve was, however, increased as shown by the dotted line on the curve, by a roughly constant amount of .0175 cu.ft.per.min. Air leakage was not materially altered by the extra head. For our air supply on these tests we used the larger Heynck compressor reported in Hs{Lord Ernest Hives - Chair}/Aln.6/MJ.3.10.31. connected to air cylinders. From the curve there given, it is found that the maximum air delivery at 1125 r.p.m. occurs at anything up to 70 lbs.per.sq.in. and amounts to .49 cu.ft. of free air per minute. Taking a Kestrel engine consumption at 290 pints per hour, the attached curves show that the petrol pump would take .275 cu.ft. per min. which the compressor could easily maintain, at any rate near ground level. On the Buzzard engine, however, consuming say 450 pts. per hour, the demand would be too great especially as the compressor would be running at lower speed. It is assumed in an installation that the compressor would be adjusted not to exceed the 120 lbs.per sq.in. given as the maximum air pressure by the petrol pump makers. The pump itself is capable of a much bigger delivery than the above, given the requisite air supply. Delivering freely through a .275" bore pipe without lift head, the flow was 857 pints per hour and the air consumption about .65 cu.ft. per min at low air pressures up to three times this amount for 120 lbs. air pressure. The action of the regulator appears to become more like a simple throttle under these conditions. The petrol flow did not change with air pressure; it also remained the same when the regulator was screwed down to open at 3.5 lbs. per.sq.in. Except for this case, the regulator was kept at the maker's setting throughout the tests, which we found was for the minimum petrol pressure in its range, namely opening at from 2.0 to 3.0 lbs.per.sq.in. according to air supply pressure which affects it to this extent by reason of its force on the needle valve. This setting of the regulator permits of momentary pressures of 6.0 lbs.per.sq.in. or more at times and in order to observe the effect of this the pump was connected to a Phantom carburetter float chamber with jets fitted, and set in operation. With no flow slight flooding took place. With a small flow (made by draining the float chamber) no flooding occurred, but the petrol level undulated somewhat, and with a heavy flow the level varied considerably and occasionally allowed flooding to occur. It seems probable that the bouyancy of the float is affected by the varying amounts of air carried into the petrol from the pump. We think this inclusion of air in the | ||