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).
Potential issues and improvements for fuel system components like pumps, gauges, and tanks.
| Identifier | ExFiles\Box 44\4\ Scan158 | |
| Date | 13th January 1930 guessed | |
| - 3 - The only danger is leakage at the pump valve, which is an ordinary tire-valve, and for this reason a screw-down needle on the pump spindle is recommended. Supply of air from the pump at the top of the stand pipe keeps the fuel vapor down. The large hole in the air bell prevents all danger of squirting the liquid out of the U tube if the pump is operated vigorously. In this sort of installation the only danger is a low reading after standing due to condensation of fuel vapor in the stand pipe. In use on the road a Sprengel pump is not found necessary as the agitation of the fuel releases enough vapor into the system to give a true level-reading as soon as the car runs. They would not consider that the four Sprengel pumps used on your present tank unit were necessary at all. 3. When a pressure balance line is used they have found a tendency for the gauge liquid to be spilt (in shipment of the gauges or subsequent handling) into the vertical portion of the pressure balance line on the instrument. This slug of liquid in the capillary tube gives a level-reading which is high and therefore dangerous. I am bringing you a gauge showing how they make a "removeable" joint with a rubber washer at the top of the U tube. This is sketched in SK-378. 4. Another frequent trouble with pressure-balance lines has been entry of fuel into the tank-end of the line due to insufficient baffling. On aeroplanes this is taken care of by baffles as shown in sketch. From inspection of your drawings (but not of the actual unit) they would doubt whether the baffling was adequate. Note that the baffling used on our present PI tank with central vent and shown in A-14132 attached, would be considered adequate for attaching the balance-line. 5. Attachment of gauge-glass. They believe Hobson are still using cemented joints, the cement being protected by a coating of paraffin-wax. They have two better methods: 1. Copper plating the lower end of the glass tube and soldering into the cup. 2. Fusing the capillary tube directly into the glass. Am bringing samples of both systems. - continued - | ||