| 摘要 |
PROBLEM TO BE SOLVED: To detect an objective gas extremely simply and stably for a long time without frequently performing zero-point adjustment, etc. even in cases where the concentration of the gas to be detected is extremely low. SOLUTION: A detection gas is taken out toward a gas detection part in a prescribed environment. In a state where the detection gas does not exist in the detection part, a sound wave is emitted from a sound wave emission means toward the interior of the detection part while it is reflected. A sound wave velocity measured by a sound wave reception means is obtained as a first sound velocity, with the wave velocity measured while causing the sound wave to go and return in the detection part. Thereafter, in a state where the detection gas exists in the detection part, the sound wave is emitted from the emission means toward the interior of the detection part while it is reflected. A sound wave velocity measured by the reception means is obtained as a second sound velocity, with the wave velocity measured while causing the sound wave to go and return in the detection part by the same number of times as the first sound velocity is obtained. Thereafter, the concentration of the detection gas is detected by obtaining a difference between the first and second velocities. COPYRIGHT: (C)2007,JPO&INPIT
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