Method for determining exhaustion of an electrochemical gas sensor
First Claim
1. A method for testing an amperometric electrochemical sensor operated in a galvanic mode and comprising at least one consumable electrode, and which measures a gas which comprises a component of a fluid, said sensor producing a steady state electrical output across a load resistor which is substantially proportional to concentration of the gas in the fluid, said method comprising the steps of:
- determining an initial steady state output;
changing the value of the load resistor;
observing the change in the steady state output after said changing the value of said load resistor; and
using said change in steady state output to determine whether the sensor is near the end of its useful life.
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Abstract
A method by which an oxygen measuring instrument can test the functionality of the oxygen sensor. Oxygen sensors of the galvanic type operate by consumption of an internal easily oxidizable anode, such as lead or cadmium. Failure of the sensor due to complete consumption of all of the anode material, such that the oxygen sensor is no longer able to detect oxygen, is often rapid with little warning. This invention describes an electrical test, which may be performed in-situ on the oxygen sensor by the instrument, which provides a means for detection of an imminent failure, while the sensor is still operational.
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Citations
16 Claims
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1. A method for testing an amperometric electrochemical sensor operated in a galvanic mode and comprising at least one consumable electrode, and which measures a gas which comprises a component of a fluid, said sensor producing a steady state electrical output across a load resistor which is substantially proportional to concentration of the gas in the fluid, said method comprising the steps of:
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determining an initial steady state output; changing the value of the load resistor; observing the change in the steady state output after said changing the value of said load resistor; and using said change in steady state output to determine whether the sensor is near the end of its useful life. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for testing an amperometric electrochemical sensor operated with a constant potential applied to its electrodes, comprising at least one consumable electrode and which measures a gas which comprises a component of a fluid and which gives a steady state electrical output across said electrodes which is substantially proportional to the concentration of the gas in the fluid, the method comprising:
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obtaining a first steady state electrical output at a first applied potential; changing the value of the applied potential; obtaining a new steady state electrical output after said change in said applied potential; and computing a ratio of said new steady state electrical output to said first steady state electrical output to determine whether the said sensor is near the end of its useful life. - View Dependent Claims (11, 12, 13, 14, 15, 16)
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Specification