Method and apparatus for measuring dissolved gas concentrations
First Claim
1. An apparatus for measuring dissolved oxygen and hydrogen gas concentrations which comprises:
- an electrode;
a counter-electrode;
a vessel filled with electrolyte into which the electrodes are immersed;
an oxygen and hydrogen permeable membrane having a thickness in the range of 70 μ
m to 350 μ
m partitioning said electrolyte from sample water containing said dissolved gases outside of said vessel;
at least one power source applying a potential in the range of -0.4 to -0.75 V and connecting said electrode and said counter electrode;
means measuring current generated between said electrode and said counter electrode; and
wherein the thickness of the membrane determines a potential region for a reduction limiting current plateau and a potential region for an oxidation limiting current plateau between two dissolved gas components to be measured, the combination of both of said regions producing an overlapped potential region.
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Abstract
Two dissolved gas components in sample water, for example, oxygen and hydrogen in core water, are readily quantitatively determined in one and same membrane-type oxygen meter by using a membrane producing an overlapped potential region where a potential region for an oxidation limiting current plateau is overlapped with that for a reduction limiting current plateau between two dissolved gas components, and applying to between a pair of an electrode and a counter-electrode a more positive potential than the equilibrium potential for oxidation-reduction reaction of one of the two dissolved gas components principally, thereby measuring a current generated between the electrodes, and a more negative potential than the equilibrium potential for oxidation-reduction reaction of the other dissolved gas component, when desired, thereby measuring a current generated between the electrodes, and quantitatively determining a concentration of the first dissolved gas component from the latter current quantity and quantitatively determining a concentration of the other dissolved gas component from a difference between the said two current quantities.
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Citations
20 Claims
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1. An apparatus for measuring dissolved oxygen and hydrogen gas concentrations which comprises:
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an electrode; a counter-electrode; a vessel filled with electrolyte into which the electrodes are immersed; an oxygen and hydrogen permeable membrane having a thickness in the range of 70 μ
m to 350 μ
m partitioning said electrolyte from sample water containing said dissolved gases outside of said vessel;at least one power source applying a potential in the range of -0.4 to -0.75 V and connecting said electrode and said counter electrode; means measuring current generated between said electrode and said counter electrode; and wherein the thickness of the membrane determines a potential region for a reduction limiting current plateau and a potential region for an oxidation limiting current plateau between two dissolved gas components to be measured, the combination of both of said regions producing an overlapped potential region. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for measuring dissolved oxygen and hydrogen gas components comprising:
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providing a sample water containing two dissolved gas components to be measured; providing a membrane having a thickness in the range of 70 μ
m to 350 μ
m permeable by said dissolved gas components, the thickness of said membrane determining and a potential region for a reduction limiting current plateau and a potential region for an oxidation limiting current plateau between said two dissolved gases, the combination of both of said regions producing an overlapped potential region, said membrane separating a vessel from said sample water, said vessel being filled with electrolyte and containing an electrode and a counter-electrode immersed in said electrolyte and connected by a power source;applying a first potential in the range of -0.4 to -0.75 V from said power source to produce said overlapped potential region and measuring a first current between the electrodes; applying a second potential from said power source which is the oxidation-reduction equilibrium potential for one of the gases to be measured and measuring a second current between the electrodes to determine the concentration of said one of said gases; and determining the concentration of the remaining one of said two dissolved gases by the difference between said first and second currents. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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20. A method for measuring dissolved oxygen and hydrogen gas components in a sample water comprising:
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providing a sample water containing dissolved hydrogen and oxygen gases; providing a membrane having a thickness in the range of 70 to 350 μ
m and permeable by said dissolved hydrogen and oxygen, the thickness of said membrane determining a potential region for an oxygen reduction limiting current plateau and a potential region for a hydrogen oxidation limiting current plateau, the combination of both of said regions producing an overlapped potential region, said membrane separating a vessel filled with electrolyte from said sample water and containing an electrode and a counter electrode immersed in said electrolyte and connected by a power source;applying a first potential in the range of -0.4 to -0.75 V from said power source to produce said overlapped potential region and measuring a first current between the electrodes; applying a second potential from said power source which is the oxidation-reduction equilibrium potential for a dissolved oxygen gas, and measuring a second current between the electrodes to determine the concentration of said oxygen gas; and determining the concentration of the dissolved hydrogen by the difference between said first and said second currents.
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Specification