GB675000A - Improvements in or relating to apparatus for measuring the contents of liquid fuel containers - Google Patents

Abstract

675,000. Indicating volume of liquid. MULLER, B. M. Nov. 14, 1950 [Nov. 14, 1949], No. 29105/49. Class 123(i) The total volume of liquid in one or a number of fuel containers, even when tilted as in aircraft, is indicated by four dip tubes 11 in the liquid fuel each leading to a side branch 13 of a (mercury) manometer 14 the average depth being thus obtained in the central tube 15 of the manometer and indicated on a pressure gauge 23. The tube 15 also has a dip tube 19 supplied with pressure air from 18 through a surge preventing flow restrictor 29 whereby the level of mercury in 15 varies the air pressure in tube 21 leading to a sealed chamber 22 provided with a flexible diaphragm forming part of the pressure gauge 23. In Fig. 2 a number of tanks 36-41 each has four dip tubes leading to its own manometer 44. A dip tube in the centre tube of each manometer also has a pressure air supply and flow restrictor 51 and is connected by 48 to a selector valve unit 49. The selector valve unit may be individually or simultaneously connected to the manometer tubes 48 by hand manipulating the selector valve unit 49. Conduits 52 from 49 lead each to one of six concentric annular chambers 53 of equal cross-sectional area in a main mercury manometer 54 the pressure in the dip tube in the central chamber 55 operating a volume (pressure) indicating gauge 35 in the same way as in Fig. 1. The manometer 54 comprises concentric chambers 53, Fig. 3, and a central chamber 55 all closed at their upper ends. Conduits 59 from 55 are from the centres of 44 and from the tanks 36-41 and also from the pressure gauge casing 35 lead to a common vent at atmospheric pressure or a constant low air pressure. The selector valve unit can be set to connect one or more of the manometers 44 to the main manometer 54 so as to measure the contents of any one tank or the total of a selected number of tanks. To prevent loss of mercury if the aircraft is flown upside down the dip tubes may be fitted with porous ceramic plugs which allow air but not mercury to pass through. Such plugs may also be fitted in the vent pipes from'the manometers. For tanks in which the horizontal cross-section varies from top to bottom, the centre tube 61 of the mercury manometer is fitted with a core, shaped in correlation with the shape of the tank to give accurate readings of the volume. The minimum effective cross-sectional area of the central tube 61 should be greater than the total cross-Sectional area of the side branches: The apparatus may be used for bag tanks the dip tubes being small diameter flexible pipes secured at the top and bottom wall of the tank by fittings including external and internal plates clamping part of the walls between them. To avoid inertia effects due to vertical acceleration the gauge indicator may be designed accordingly.