US3774104A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Liquid conductivity measuring apparatus
Assignee: Hach Co
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Filing: 1971-12-13
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Granted: 1973-11-20
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Expires: 1991-12-13
Abstract
Abstract Apparatus for measuring the conductivity of a liquid including an improved probe adapted for confining conduction between a pair of electrodes to a predetermined path and for housing temperature compensation elements in thermal proximity to the liquid. The probe incorporates an insulating element being characterized in that it defines the boundaries of a pair of channels between the electrodes in which all electrical conduction through the liquid takes place. The insulating element additionally defines input conduits for entry of the liquid into the channels as the probe is immersed into the liquid and exit conduits from which the air displaced from the channel can escape, the input and exit conduits intersecting the channels at points of equal potential with respect to the potential at either electrode so that conduction through these conduits to the external environment is prevented.
Inventors
- 👤 M Andersen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 18:10
CPC Classifications
G; G01; G01N; G01N27/00; G01N27/02; G01N27/04; G01N27/06; G01R; G01R27/00; G01R27/02; G01R27/22
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
277 words
Apparatus for monitoring the conductivity of a liquid comprising an oscillator producing a constant amplitude electrical signal; an operational amplifier having an input terminal for receiving said signal, an output terminal, and a feedback network between said input and output terminals which determines the gain of said amplifier and the voltage level at said output terminal; a probe for insertion into said liquid comprising in combination, (a) a probe housing, (b) a spaced-apart pair of electrodes and temperature sensing elements within said housing and in thermal proximity to said liquid, (c) insulating means for holding said electrodes and said temperature sensing elements, said insulating means being shaped to include (i) a first cut-away portion which defines a substantially closed channel between said electrodes and (ii) a second cut-away portion which intersects said channel and defines entry and exit conduits wHich provide paths for the entry of said liquid into said channel and the exit of air from said channel upon insertion of said probe into said liquid, each of said conduits intersecting said channel at a point having the same electrical potential with respect to said electrodes as the electrical potential of every other point of conduit intersection into said channel, and (d) electrical leads extending from said housing and connecting said electrodes and said temperature sensing elements respectively to said output terminal and into said feedback network of said operational amplifier such that said electrodes are maintained at a potential difference to the voltage at said amplifier output terminal and said voltage varies with the temperature of said liquid; and current sensing means in series with said electrodes for indicating the electrical conductivity of said liquid.
Claim 2
Dependent Claim
277 words
Apparatus for monitoring the conductivity of a liquid comprising an oscillator producing a constant amplitude electrical signal; an operational amplifier having an input terminal for receiving said signal, an output terminal, and a feedback network between said input and output terminals which determines the gain of said amplifier and the voltage level at said output terminal; a probe for insertion into said liquid comprising in combination, (a) a probe housing, (b) a spaced-apart pair of electrodes and temperature sensing elements within said housing and in thermal proximity to said liquid, (c) insulating means for holding said electrodes and said temperature sensing elements, said insulating means being shaped to include (i) a first cut-away portion which defines a substantially closed channel between said electrodes and (ii) a second cut-away portion which intersects said channel and defines entry and exit conduits wHich provide paths for the entry of said liquid into said channel and the exit of air from said channel upon insertion of said probe into said liquid, each of said conduits intersecting said channel at a point having the same electrical potential with respect to said electrodes as the electrical potential of every other point of conduit intersection into said channel, and (d) electrical leads extending from said housing and connecting said electrodes and said temperature sensing elements respectively to said output terminal and into said feedback network of said operational amplifier such that said electrodes are maintained at a potential difference to the voltage at said amplifier output terminal and said voltage varies with the temperature of said liquid; and current sensing means in series with said electrodes for indicating the electrical conductivity of said liquid.
Claim 3
Dependent Claim
52 words
Apparatus according to claim 1 wherein said temperature sensing elements have resistance characteristics varying inversely to changes in temperature and said feedback network provides degenerative feedback, whereby the voltage at said output terminal of the amplifier varies inversely to the variations in the current carrying capabilities of said liquid during temperature changes.
Claim 4
Dependent Claim
151 words
A probe for use in monitoring the electrical conductivity of a liquid comprising in combination, a pair of electrodes maintained at different electrical potentials, and insulating means for holding said electrodes in spaced-apart relation to each other, said insulating means being shaped to include a. a first cut-away portion which defines a substantially closed channel between said electrodes and b. a second cut-away portion which intersects said channel and defines entry and exit conduits which provide paths for the entry of said liquid into said channel and the exit of air from said channel upon insertion of said probe into said liquid, each of said conduits intersecting said channel at a point having the same electrical potential with respect to said electrodes as the electrical potential of every other point of conduit intersection into said channel, whereby electrical conduction through said conduits to the liquid outside of said channel is prevented.
Claim 5
Dependent Claim
151 words
A probe for use in monitoring the electrical conductivity of a liquid comprising in combination, a pair of electrodes maintained at different electrical potentials, and insulating means for holding said electrodes in spaced-apart relation to each other, said insulating means being shaped to include a. a first cut-away portion which defines a substantially closed channel between said electrodes and b. a second cut-away portion which intersects said channel and defines entry and exit conduits which provide paths for the entry of said liquid into said channel and the exit of air from said channel upon insertion of said probe into said liquid, each of said conduits intersecting said channel at a point having the same electrical potential with respect to said electrodes as the electrical potential of every other point of conduit intersection into said channel, whereby electrical conduction through said conduits to the liquid outside of said channel is prevented.
Claim 6
Dependent Claim
57 words
A probe for use in monitoring the electrical conductivity of a liquid as set forth in claim 3 further including a temperature compensating network operatively associated with said electrodes and effective to vary said electrical potential between said electrodes to make electrical conduction between said electrodes constant for said liquid irrespective of the temperature of said liquid.
Claim 7
Dependent Claim
56 words
A probe for use in monitoring the electrical conductivity of a liquid as set forth in claim 4 wherein said temperature compensating network includes temperature sensitive means and wherein said insulating means is further shaped to include a cut-away portion which defines a conduit for holding said temperature sensitive means in thermal proximity with said liquid.
Claim 8
Dependent Claim
184 words
In a probe for use in monitoring the conductivity of a liquid, the combination comprising: a pair of electrodes maintained at different electrical potentials, insulating means for holding said electrodes in spaced-apart relationship to each other, said insulating means being shaped to include a. first and second cut-away portions respectively defining a pair of substantially closed channels between said electrodes for creating a pair of conduction paths between said electrodes when said channels are filled with said liquid, b. third and fourth cut-away portions respectively defining an entry conduit into each of said channels for allowing said liquid into said channels upon immersion of said probe into said liquid and c. fifth and sixth cut-away portions respectively defining an exit conduit from each of said channels for allowing air to escape said channel as said liquid enters said channel, each of said entry and exit conduits intersecting said channels at a point equidistant from said electrodes such that the points of intersection with said respective channels are at equal electrical potentials, whereby conduction through said ports into liquid outside of said channels is prevented.
Claim 9
Dependent Claim
184 words
In a probe for use in monitoring the conductivity of a liquid, the combination comprising: a pair of electrodes maintained at different electrical potentials, insulating means for holding said electrodes in spaced-apart relationship to each other, said insulating means being shaped to include a. first and second cut-away portions respectively defining a pair of substantially closed channels between said electrodes for creating a pair of conduction paths between said electrodes when said channels are filled with said liquid, b. third and fourth cut-away portions respectively defining an entry conduit into each of said channels for allowing said liquid into said channels upon immersion of said probe into said liquid and c. fifth and sixth cut-away portions respectively defining an exit conduit from each of said channels for allowing air to escape said channel as said liquid enters said channel, each of said entry and exit conduits intersecting said channels at a point equidistant from said electrodes such that the points of intersection with said respective channels are at equal electrical potentials, whereby conduction through said ports into liquid outside of said channels is prevented.
Claim 10
Dependent Claim
66 words
In a probe for use in monitoring the conductivity of a liquid as set forth in claim 6 wherein said channels are disposed substantially parallel to the level of said liquid when said probe is immersed in said liquid and whereby the upper surfaces of said channels are inclined upwardly from said electrodes to said exit conduits to facilitate said escape of air from said channels.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-11-19 | 1977-05-21 | 1977-11-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-11-19 | 1981-05-21 | 1981-11-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-11-19 | 1985-05-21 | 1985-11-20 | $7700.00 | Window Closed / Lapsed |