Abstract: An improved mass flow meter is disclosed for measuring the flow rate of a fluid through a thin walled sensor tube that has the feature of high sensitivity to the temperature of the fluid within the sensor tube. The sensor tube is wound with closely coupled resistance elements of insulated wire. Measurement is accomplished with a conventional bridge connection to the sensor resistance elements. The bridge is designed to remain in balance over a wide range of ambient temperature at a zero flow rate. Fluid flow through the sensor tube upsets the uniform temperature gradient with heat loss being greater upstream so that the balance of the sensor resistance elements installed or coupled to the sensor tube (which elements are heated by a power supply) is progressively upset with increasing flow.

Abstract: This disclosure relates to a flow meter having an improved flow restrictor for creating laminar flow in the flow meter. The improved flow restrictor is an adjustable bypass or flow restrictor which comprises a stack of alternate slotted discs and non-slotted, smaller diameter, washers with a diameter of 80% of the slotted discs, to form a plurality of micro-channels 0.09 mm square and 3 mm long which is a length to area ratio sufficient to assure laminar fluid flow through the flow meter.