GB313662A - Improvements relating to liquid level or depth gauges - Google Patents

Abstract

313,662. Higginson, J. March 20, 1928. Indicators, alarm and signal.-In a liquid-fuel tank for a motor vehicle, from which fuel is drawn by suction, the withdrawal pipe is provided with a bell fitting extending to the bottom of the tank, and a pipe exending from the bell to an alarm or indicator to indicate the fall of the liquid below a predetermined level. A vacuum feed device a, Fig. 1, is connected to a pipe b terminating in a bell f dipping into the liquid. During suction, air is drawn in through pipe p open at the top, and mixes with the fuel, so that on the return flow of fuel down the pipe b this air is entrained and keeps the bell f full of air. The depth of fuel is indicated by a gauge n. A small aperture 4 is provided at the level of the end of the pipe b, so that when the fuel falls to that level, the gauge n reads zero at periods of non-suction, and below zero during periods of suction. In Fig. 2, the bell f is connected by a pipe g to a cylinder h having a piston i adapted to uncover a signal lamp j when suction is exerted on the pipe g due to fall of the level below the end of the pipe b. In a modification, Fig. 3, not shown, the movement of the piston i is utilized to complete the circuit of an electric lamp. In another modification, Fig. 4, not shown, a. whistle is placed in the outer end of the tube g. A pressure gauge n may be provided on the tube g to indicate the level, and a small hole q, Fig. 5, may be provided to admit air to the pipe b during the suction period, this entrained air being carried into the bell f during the return flow. The Provisional Specification describes also a modification in which the supply pipe has a non-return valve to prevent return flow, and a second pipe is provided with an air leak and with a valve which cuts off communication with the supply pipe during suction but not during the return flow. In other modifications, the second pipe may include a Venturi tube, or a small chamber may be connected to the supply pipe, into which air is dra.wn during suction and from which it is delivered into the bell during return flow. Specifications 179,966, 268,565, 279,282 and 284,594 are referred to.