GB1219710A - A fluid flowmeter - Google Patents

Abstract

1,219,710. Measuring fluid flow rate electrically. STANDARD TELEPHONES & CABLES Ltd. June 18,1969. No.30936/69. Heading G1N. The rate of flow of a fluid through a conduit 1, Fig. 1 of heat conductive material is determined from the heat dissipation differential between two heated thermistors 5, the first in assembly 2 in thermal contact with the conduit 1, and the second in assembly 3 in thermal contact with the fluid via a probe 13 whose cross-sectional area is varied along its length to obtain uniform heat dissipation to the fluid along its length. Each thermistor 5 is maintained at a constant temperature and thus at a constant resistance by automatic control of the heating current. The power fed to assembly 2 is indicative of the temperature of the fluid and conduit and the power fed to assembly 3 additionally compensates for the heat removed by the flowing fluid. Hence the power difference is indicative of the fluid flow rate. In a modification, Fig. 2 for use with flowing liquids, the probe 13 of assembly 3 is located outside the conduit 1 upstream of a restriction 16, the excess pressure on the upstream side of the restriction causing the liquid to rise into the assembly 3 by an amount dependent on the rate of liquid flow. The flowmeter may be combined with a further assembly similar to assembly 2 for measuring the temperature of the fluid at another location to determine the temperature change in the fluid and the total heat supplied by, e. g. a central-heating system.