Wire-wound sensor componentry for mass flow meters

Abstract

Microprocessor-based thermal dispersion mass flow meters (i.e., thermal anemometers) are described that use temperature sensing elements in its flow sensor probe(s) in addition to the two elements commonly used. Such systems allow for automatically managing changes in gas selection, gas temperature, gas pressure, and outside temperature. One mass flow meter described has a flow sensor with four temperature sensing elements, wherein one pair is provided in a temperature sensor probe and another pair in a velocity sensor probe. Another variation operates without a separate temperature sensor probe and integrates all function into a single three-sensor probe. Such a device may also be used in conjunction with a one- or two-sensor temperature probe.

What is claimed is: 
     
         1 . An apparatus for use in a mass flow meter for immersion in fluid flow comprising:
 a Resistance Temperature Detector (RTD) comprising a wire winding set upon a non-conductive spacer and defining having a heated length; and   a proximal temperature sensor received within the spacer.   
     
     
         2 . The apparatus of  claim 1 , further comprising an elongate temperature sensor. 
     
     
         3 . The apparatus of  claim 1 , further comprising a housing shell for the RTD and proximal temperature sensor. 
     
     
         4 . The apparatus of  claim 1 , further comprising a distal temperature sensor received within the spacer. 
     
     
         5 . The apparatus of  claim 1 , wherein a surface of at least one of the proximal and distal temperature sensors is located within about 0.1 inches of the heated length of the RTD. 
     
     
         6 . The apparatus of  claim 5 , wherein the surface of at least one of the proximal and distal sensors and the heated length of the RTD overlap. 
     
     
         7 . The apparatus of  claim 1 , further comprising a computer processor for outputting mass velocity measurements in real time. 
     
     
         8 . The apparatus of  claim 7 , further comprising a transmitter for wireless communication of the measurements. 
     
     
         9 . The apparatus of  claim 1 , wherein the RTD comprises a platinum wire winding. 
     
     
         10 . The apparatus of  claim 1 , wherein the spacer is slotted or recessed at a proximal end to receive the proximal temperature sensor therein. 
     
     
         11 . The apparatus of  claim 10 , wherein the proximal temperature sensor comprises a thin-film RTD. 
     
     
         12 . The apparatus of  claim 4 , wherein the spacer is slotted or recessed at a distal end to receive the distal temperature sensor therein. 
     
     
         13 . The apparatus of  claim 12 , wherein the distal temperature sensor comprises a thin-film RTD. 
     
     
         14 . The apparatus of  claim 4 , wherein the spacer includes four lumen with two lumen receiving electrical leads for the wire-wound RTD and two lumen receiving electrical leads for the distal temperature sensor.