Fluid density monitor for aircraft fuelling - uses float and magnet arrangement moving between limits in container

摘要

A device for monitoring the density of a fluid flowing through a pipe, in partic, for use with fuels, using a float moving between limits, is designed to be simple and robust and to operate reliably and without maintenance for long periods. The device may be used in aircraft fuel systems for safety purposes to distinguish different propellant types by their density differences in order to avoid incorrect fuelling. It clearly indicates density differences of the order of one hundredth and responds to those of one thousandth. A two piece magnet (34) is attached to the float (20) and a similar magnet (36) moves in a container (35) which limits its range of movement and thus that of the float. The position of the second magnet controls the fuelling valve.