Patent Number: 044407173
Section: claims

1. An apparatus for sensing the level of a liquid contained within a pressure vessel comprising: a. a plurality of axially spaced elongated heat conductive housings, each of said housings having  b. means for supplying energy to each of said heating elements;  c. means for measuring the net voltage generated by each of said first thermocouple junctions and said second thermocouple junctions;  d. a first tubular element having an interior, an exterior, an enclosed lower end, and means for fluid communication between said interior and said exterior said first tubular element surrounding said plurality of axially spaced elongated heat conductive housings and extending substantially the length of said housings, whereby liquid or liquid flashing to gas within said first tubular element exits through said fluid communicating means upon a pressure reduction or change in fluid level in said pressure vessel thereby maintaining equalized liquid levels on said interior and exterior of said first tubular element,  e. a second tubular element having an interior, an exterior, and means for fluid communication between said interior and said exterior, said second tubular element surrounding said first tubular element, and extending substantially the length of said first tubular element; and  f. at least a portion of said fluid communicating means between said interior and said exterior of said second tubular element are axially offset from said fluid communicating means between said interior and said exterior of said first tubular element.  means for sensing the absolute temperature of at least one of said first thermocouple junctions.  means for sensing the absolute temperature of at least one of said second thermocouple junctions.  means for reducing power to at least one of said heaters when the temperature of at least one of corresponding said first thermocouples becomes excessive. 2. An apparatus as in claim 1 wherein: said fluid communicatng means between said interior and said exterior of said first tubular element are lateral input-output ports near the top and bottom thereof. 3. An apparatus as in claim 2 wherein: said fluid communicating means between said volume enclosed by said splash guard and said exterior of said splash guard are lateral inlet-outlet ports near the top and bottom of said splash guard. 4. An apparatus as in claim 1, 2 or 3 also comprising 5. An apparatus as in claim 1, 2, or 3 also comprising: 6. An apparatus as in claim 4 also comprising: 7. An apparatus of claim 1, 2 or 3 wherein: (a) said first tubular element is hydraulically divided forming at least two level sensing sections, each of said level sensing sections having said fluid communicating means between said interior and said exterior of said first tubular element and at least one elongated heat conductive housing, (b) said second tubular element is hydraulically divided proximate said hydraulic division in said first tubular element forming said at least two level sensing sections, each of said level sensing sections having said fluid communicating means between said interior and said exterior of said second tubular element, whereby at least two separate liquid levels may be measured. 8. An apparatus as in claim 7 also comprising: means for sensing the absolute temperature of at least one of said first thermocouple junctions. 9. An apparatus as in claim 7 also comprising: means for sensing the absolute temperature of at least one of said second thermocouple junctions.