Abstract: The probe is directed toward removal and sampling particulates in possibly corrosive gases in flues. A flue gas removal tube removes flue gas from a suction nozzle and feeds it into a mixed gas feed tube, the inlet of which is of a wider diameter than the outlet portion of the flue gas removal tube. A fresh air tube surrounds the mixed gas feed tube, and fresh air flows down the fresh air tube flows down the fresh air tube and then up the mixed gas feed tube along with removed flue gas. Heating coils in the fresh air tube heat both the fresh air and the mixed gas to a temperature above the prevailing dew point. A closure spaced from the outlet from the fresh air tube and the inlet to the mixed gas feed tube has a funnel shaped development which reduces eddying of fresh air and of outgoing gases. Pitot tubes determine the pressure difference in the flue as well as in the fresh air and mixed gas removal tubes and adjust the respective flows.

Abstract: An apparatus for measuring the dust contamination in flues containing corrosive dusts, particularly chimneys, in which an equal-velocity or isokinetic removal of a sample stream of gas takes place and the sample stream of gas is mixed with fresh air to reduce the dew point and fed to the evaluation filter.