System and method for obtaining compensated level measurements
First Claim
1. A compensated level measuring system for measuring the level of material housed in a vessel, said material being characterized by certain electrical characteristics such as dielectric constant and conductivity, comprising:
- a. first probe means having a first probe portion mounted at a fixed position within said vessel, for obtaining a level signal which is a function of said material level and said electrical characteristics;
b. second probe means having a second probe portion maintained within said vessel at a position always submerged in said material, for obtaining a reference signal which is a function of said electrical characteristics;
c. said second probe means comprising means located external to said second probe portion and operable while said second probe portion is submerged in said material for adjusting said reference signal to provide a compensated reference signal;
d. means for deriving a compensated level signal as a predetermined function of said level signal and said compensated reference signal; and
e. wherein said first probe means comprises a first electronic source circuit in combination with said first probe portion for generating said level signal, and said second probe means comprises a second electronic source circuit in combination with said second probe portion for generating said reference signal.
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Abstract
A compensated level measuring system is disclosed for measuring the level of the material housed in a vessel, the system incorporating compensation means for compensating for variations in the dielectric constant of the material. A two element measuring system is used, having a first element mounted at a fixed position within the vessel containing the material for obtaining a level signal which is a function of the material level, and a second element maintained within the vessel and always submerged in the material for obtaining a reference signal. Means are provided for adjusting the reference signal so that it can accurately compensate for variations in the level signal which occur independently of the material level. The compensating means is provided either by a mechanical embodiment in which the reference signal is effectively tuned by modifying the position of the reference probe, or electronic means where the effective reference signal is modified by an error function to compensate for errors introduced by changes in the dielectric constant of the material being measured.
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Citations
26 Claims
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1. A compensated level measuring system for measuring the level of material housed in a vessel, said material being characterized by certain electrical characteristics such as dielectric constant and conductivity, comprising:
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a. first probe means having a first probe portion mounted at a fixed position within said vessel, for obtaining a level signal which is a function of said material level and said electrical characteristics; b. second probe means having a second probe portion maintained within said vessel at a position always submerged in said material, for obtaining a reference signal which is a function of said electrical characteristics; c. said second probe means comprising means located external to said second probe portion and operable while said second probe portion is submerged in said material for adjusting said reference signal to provide a compensated reference signal; d. means for deriving a compensated level signal as a predetermined function of said level signal and said compensated reference signal; and e. wherein said first probe means comprises a first electronic source circuit in combination with said first probe portion for generating said level signal, and said second probe means comprises a second electronic source circuit in combination with said second probe portion for generating said reference signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A compensated level measuring system for measuring the level of a material housed in a vessel having walls, said material having electrical characteristics including a dielectric constant K which may vary during usage of said system, comprising:
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a level probe assembly comprising a level probe mounted at a fixed position within said vessel in combination with a level electronic source circuit, for generating a level signal which is a function of said level; a reference probe assembly comprising a reference probe always submersed in such material, in combination with a reference electronic source circuit, for generating a reference signal; and means for adjusting the position of said reference probe, whereby said probes can be geometrically matched. - View Dependent Claims (21, 22)
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23. A compensated level measuring system for measuring the level of a material housed in a vessel, said material having a dielectric constant K which may vary during usage of said system, comprising:
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a level probe assembly comprising a level probe mounted at a fixed position within said vessel in combination with a level electronic source circuit, for generating a level signal which is a function of said level; a reference probe assembly comprising a reference probe submerged in said material, in combination with a reference electronic source circuit, for generating a reference signal; and electronic compensating means for compensating said generated reference signal in accordance with a predetermined function, and for deriving a compensated level signal as a predetermined function of said level signal and said compensated reference signal. - View Dependent Claims (24, 25, 26)
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Specification