Patent ID: 6658931
Filing Date: 2003-12-09
Classification: G01F

Abstract:
A plurality of autonomous fluid flow sensor and controller assemblies which share a common power source and provide flow indicative signals to a common remote location, each flow sensor and control assembly otherwise autonomously operable independent of the other flow sensor and control assemblies and comprising:a housing; a cantilevered flow sensing probe connected to the housing at one end and extending into a flow in good heat transfer relation therewith; an electrically heatable member within the probe; a first temperature sensitive resistor within the probe and in close proximity to the heatable member and solely thermally contacting the heatable member; a second temperature sensitive resistor within the probe and remote from the electrically heatable member and thermally isolated from the heatable member; and electrical circuitry within the housing receiving power from the common power source for supplying a substantially constant currents to each of the temperature sensitive resistors and a variable current to the heatable member, the electrical circuitry including means responsive to a voltage drop across the first temperature sensitive resistor for controlling the variable current and means responsive to the variable current for providing control signals to influence the fluid flow rate.