Calibration method for gas analysis apparatus, gas analysis system, and pressure varying device

1. A calibration method for a gas analysis apparatus, comprising:

connecting a pressure varying device to both a sample gas introduction port and a gas discharge port of the gas analysis apparatus;

depressurizing both the sample gas introduction port and the gas discharge port to a same pressure by the pressure varying device;

introducing calibration gas having a known concentration from a calibration gas introduction port of the gas analysis apparatus in a depressurized state; and

calculating a pressure correction factor for the gas analysis apparatus with use of (i) measurement result of the calibration gas by the gas analysis apparatus and (ii) the known concentration.

2. The calibration method for a gas analysis apparatus according to claim 1 , further comprising:

depressurizing both the sample gas introduction port and the gas discharge port to multiple pressures by the pressure varying device; and

calculating the pressure correction factor for the gas analysis apparatus so that a measurement result of the calibration gas at each of the multiple pressures becomes equal to a measurement result of the calibration gas at a predetermined reference pressure.

3. The calibration method for a gas analysis apparatus according to claim 2 , wherein the predetermined reference pressure is pressure at time of preparing a calibration curve for the gas analysis apparatus or pressure at time of zero and span calibration.

4. The calibration method for a gas analysis apparatus according to claim 1 , further comprising:

introducing an excessive amount of the calibration gas from the calibration gas introduction port; and

measuring the calibration gas while making the calibration gas overflow from the sample gas introduction port.

5. The calibration method for a gas analysis apparatus according to claim 1 , further comprising:

introducing calibration gases for respective multiple measurement target components; and

calculating pressure correction factors for the respective multiple measurement target components.

6. The calibration method for a gas analysis apparatus according to claim 5 , further comprising:

mixing and introducing the calibration gases for the respective multiple measurement target components; and

calculating the pressure correction factors for the respective multiple measurement targets.

7. The calibration method for a gas analysis apparatus according to claim 1 , wherein the gas analysis apparatus includes an atmosphere introduction port, further comprising:

connecting the pressure varying device to the atmosphere introduction port; and

depressurizing both the sample gas introduction port and the gas discharge port to a same pressure.

8. The calibration method for a gas analysis apparatus according to claim 1 , wherein the gas analysis apparatus is of a vehicle-mounted type.

9. A pressure correction method for a gas analysis apparatus, comprising:

with use of the pressure correction factor obtained by the calibration method according to claim 1 , correcting a measurement result of actual measurement by the gas analysis apparatus to a measurement result at reference pressure for the gas analysis apparatus on a basis of pressure at time of the actual measurement.

10. An inspection method for a gas analysis apparatus, comprising:

connecting a pressure varying device to both a sample gas introduction port and a gas discharge port of the gas analysis apparatus having a pressure correction function using a pressure correction factor;

depressurizing both the sample gas introduction port and the gas discharge port to a same pressure by the pressure varying device;

introducing calibration gas having a known concentration from a calibration gas introduction port of the gas analysis apparatus in a depressurized state; and

comparing a measured value after correction using the pressure correction factor for the gas analysis apparatus and the known concentration of the calibration gas at reference pressure.

11. A gas analysis system comprising:

a gas analysis apparatus configured to analyze a measurement target component in sample gas, and to calculate a pressure correction factor with use of (i) a measurement result of calibration gas having a known concentration which is introduced into the gas analysis apparatus via a calibration gas introduction port in a depressurized state and (ii) the known concentration; and

a pressure varying device configured to vary pressure of the gas analysis apparatus, wherein the pressure varying device includes

a first flow path whose one end is configured to be connected to a sample gas introduction port of the gas analysis apparatus,

a second flow path whose one end is configured to be connected to a gas discharge port of the gas analysis apparatus, and

a pump configured to depressurize both the sample gas introduction port and the gas discharge port to a same pressure via the first flow path and the second flow path.

12. The gas analysis system according to claim 11 , wherein the first flow path and the second flow path are connected to the pump via a merged flow path.

13. The gas analysis system according to claim 12 , further comprising:

an atmosphere introduction path for introducing atmosphere into the merged flow path; and

in the atmosphere introduction path, a pressure regulation part that regulates pressures in the first flow path and the second flow path.

14. The gas analysis system according to claim 11 , further comprising

a third flow path whose one end is to be connected to an atmosphere introduction port of the gas analysis apparatus, wherein the pump is further configured to depressurize the atmosphere introduction port via the third flow path.