Thermal dispersion mass flow rate and liquid level switch/transmitter

A thermal dispersion flow sensing apparatus comprising:

• a fluid flow conduit having a wall defining the fluid flow path and having at least one reduced thickness area in said wall adapted to receive a detector element;
• a generally flat detector comprising a temperature sensitive element on an electrically insulative, thermally conductive substrate, said detector being mounted on said reduced thickness area of said conduit;
• and
• electrical conductors connected to said temperature sensitive element and adapted to be connected to external signal processing circuitry.

A thermal dispersion switch/transmitter apparatus for selectively sensing flow, mixing, phase, condition, liquid level, and interface between non-miscible materials in a fluid media, said apparatus comprising:

• a container having a wall for containing the media and having at least one area of reduced thickness in said wall;
• a first detector comprising a first temperature sensitive element for sensing the temperature of a thermally conductive region, said detector being thermally coupled to said reduced thickness area, said thermally conductive region in said reduced thickness area being shaped and configured to provide an operationally effective thermal transfer between the media in said container and said detector;
• and
• an electrical circuit to which said electrical thermally conductive region is coupled, said circuit providing operationally effective power to effect a temperature differential between said thermally conductive region and said media, said circuit having an indicator providing information as to the state of the media in said container in relation to the temperature of said first temperature sensitive element.

A method of constructing a thermal dispersion switch/transmitter, the method comprising:

• forming at least one area of reduced thickness in the wall of a fluid conduit;
• selecting a detector comprising a temperature sensitive element on a thermally conductive substrate;
• and
• mounting the detector on the reduced thickness area of the fluid conduit wall so that said substrate conforms to the contours of said reduced thickness area.

A method of constructing a thermal dispersion switch/transmitter, the method comprising:

• forming at least one area of reduced thickness in the wall of a fluid conduit;
• selecting a solid state detector comprising a temperature sensitive element on a thermally conductive base;
• mounting the detector on the reduced thickness area of the fluid conduit wall;
• and
• connecting the detector in an electrical circuit which provides operationally effective power to the detector chip and provides a signal indicative of the fluid flow in the conduit.

A thermal dispersion switch/transmitter comprising:

• a hollow probe comprising a thermal well, said probe having a proximal end and a distal end separated by an enclosing side wall, said proximal end being shaped and configured to be mounted in the wall of a fluid container;
• a mounting element secured to and closing said distal end of said probe;
• a first area of reduced thickness arranged generally normal to the longitudinal axis of and inside said probe;
• a first detector comprising a first temperature sensitive element on an electrically ensulative thermally conductive base, said first detector being mounted in said reduced thickness area within said probe and adapted to be positioned within the fluid in the container, said reduced thickness area being shaped and configured to provide an operationally effective thermal transfer between the fluid in said container and said detector;
• and
• a power source operationally effectively coupled to said first detector to effect a temperature differential between the fluid in the container and said first temperature sensitive element;
• said one end of said probe being shaped and configured to extend into a fluid flow conduit so that said surface directly contacts the fluid therein and locally generates a flow condition at said temperature sensitive element.

A thermal dispersion apparatus adapted to sense fluid flow past a surface on one side of a wall, the apparatus comprising:

• at least one reduced thickness area in said wall,
• a first detector comprising a first temperature sensitive element on electrically insulative, thermally conductive base, said detector being thermally coupled to said reduced thickness area of said wall, said reduced thickness area being shaped and configured to provide an operationally effective thermal transfer between the fluid in contact with said surface and said detector;
• means for sensing the temperature of said first temperature sensitive element;
• means for heating said first temperature sensitive element;
• means for providing input power and control signals to said heating means;
• and
• means for transmitting output signals from said temperature sensing means.