| 摘要 |
PURPOSE:To measure humidity in a high temperature gas at a low cost, by applying two different voltages to an oxygen concentration sensor, wherein a gas diffusing speed hole is provided in an oxygen ion transmitting body, and obtaining a limit current which is proportional to the oxygen concentration. CONSTITUTION:A disc shaped cathode 22 is formed on the upper surface of an oxygen ion transmitting body 21, and an anode 23 is formed on the lower surface. A lid body 25 is fixed to the upper part thereof by glass. A gas diffusing speed hole 24 for diffusing oxygen gas is provided in the lid body 25. In order to obtain the humidity by using an oxygen concentration sensor constituted in this way, at first, the first specified voltage is applied through a lead wire 27, and the first limit current, which is proportional to the concentration of the oxygen flowing in the circuit, is measured. Then the second specified voltage, which is different from the first voltage, is applied, and the second limit current is measured. By utilizing the fact that the difference between the first and second limit currents is proportional to humidity, the humidity is obtained by the relationship between the current difference obtained beforehand and steam concentration. |
