To provide an exhaust gas sampling device capable of recovering the measurement state of a measuring device for measuring a material having an infinitesimal concentration included in exhaust gas to the normal state quickly after the backwash of a filter.
This device has a constitution wherein supply of a sampled exhaust gas to the measuring device 33 is stopped and the filter is back-washed, and then purge air is sent from the upstream side of the filter 27 into a gas duct 21 through the filter 27, and hereby dust or a measuring object material which is removed from the filter by back washing and rescattered is purged into the gas duct 21, and then supply of the sampled exhaust gas to the measuring device 33 is started. Hot air is preferable as the purge air. Purging or backwash may be performed by using inert gas. Air blow may be performed before purging. In this case, the air is preferably heated. The sectional shape of a ventilation part of the filter may be roughly equalized to the sectional shape of a backwash line by sealing an air hole on the peripheral part or the like.
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