Temperature and low water monitoring for boiler systems

Abstract

A dual functionality temperature control measurement and low water cut-off measurement system is taught within a single tapping to a boiler. This dual functionality combines a low water cut-off and temperature sensor into one control utilizing a sensing element suitable for use in a single existing tapping for a boiler. Independent of low water functionality, the temperature sensor is also capable of monitoring temperature as a replacement probe in an existing temperature sensor-only well. A conductive member provides a compression fit inside the probe well for thermistors, while simultaneously providing conduction with the well interior for a low water cutoff signal in a two-conductor well.

1 - 5 . (canceled) 
     
     
         6 . An immersion thermowell adapted for mounting to the wall of a vessel, adapted to isolate a sensor from contact with liquid in said vessel, said sensor remaining in a thermal and electrical communicating relationship with said liquid, further adapted to allow a probe to measure thermal and electrical properties of said liquid, comprising: an electrically conductive housing shell coaxially joined to an electrically insulating collar coaxially joined to an electrically and thermally conductive sensor tube, forming a generally cylindrical chamber extending coaxially within, and having first and second ends, the first end being open and the second end being sealed, said sensor tube having a generally smooth exterior surface and said sensor tube being electrically isolated from said housing shell by said collar. 
     
     
         7 . An immersion thermowell set forth in  claim 6  comprising a mounting means integrally formed on the surface of said housing shell, in a circumferential portion thereof of limited axial extent intermediate the first and second ends. 
     
     
         8 . An immersion thermowell with mounting means set forth in  claim 7  comprising an annular pipe thread integrally formed in said circumferential portion of said housing shell. 
     
     
         9 . An immersion thermowell set forth in  claim 6  wherein the junction of said housing shell and said collar are sufficiently sealed to prevent liquid ingress when exposed to fluid pressures typical of boiler vessels. 
     
     
         10 . An immersion thermowell set forth in  claim 6  wherein the junction of said collar and said sensor tube are sufficiently sealed to prevent liquid ingress when exposed to fluid pressures typical of boiler vessels. 
     
     
         11 . An immersion thermowell set forth in  claim 6  wherein said collar is coaxially joined to said housing shell so that said collar extends axially beyond said housing shell to a point intermediate said housing shell and said second end. 
     
     
         12 . An immersion thermowell set forth in  claim 6  wherein said sensor tube is coaxially joined to said collar so that said sensor tube extends axially beyond said collar to said second end.