| 摘要 |
The present invention is one that prevents standard gas from remaining in a standard gas line 3 to prevent a concentration of the standard gas from being reduced due to adsorption, modification, or the like of the standard gas, and has: a diluent gas line 2 that is provided with a diluent gas flow rate controlling mechanism 23; a standard gas line 3 that is provided with a standard gas flow rate controlling mechanism 33; an output gas line 4 that is joined by the diluent gas line 2 and standard gas line 3 and outputs the standard gas having a predetermined concentration; an exhaust gas line 5 that is connected to an upstream side of the standard gas flow rate controlling mechanism 33 in the standard gas line 3 and provided with an on/off valve and a flow rate control part; and a control part 6 that, depending on a flow rate of the standard gas flowing through the standard gas line 3 or the type of the standard gas, switches on/off of the on/off valve. |
