METHOD AND APPARATUS FOR CALIBRATING GAS CONCENTRATION MEASURING DEVICE

PURPOSE:To simply allow the realization of standard gas concentration and the calibration of a measuring device on the measuring spot, by circulating the standard gas in a circulatory system having a testing tank arranged thereto and adjusting the output of the sensor in the testing tank. CONSTITUTION:A sensor 3 is mounted on a testing tank 46, and a three-way cock 39 and a four-way cock 41 are changed over and clean air is introduced into a closed pipeline 42 from the air suction port 37 of a suction pipe 38 through a pipe 40 to be discharged from a pipe 44. Next, the cock 41 is changed over to close the exhaust pipe 44 and the system of a calibration apparatus 2 is filled with clean air. Zero adjustment is performed by the operation of a control means so that the output value of the sensor 3 displayed at this time becomes zero. Herein, when a standard liquid or standard gas is injected from a gas-liquid injection port 48, the concn. thereof becomes a prescribed value after a definite time. Span adjustment is performed for the output value of the sensor 3 at that time by the operation of the control means to finish the calibration work of a measuring machine.