Abstract: A dust sampling device having a sampling nozzle is provided. The nozzle is provided with an inlets the diameter of which is variable. The diameter of the nozzle can be instantaneously changed, while keeping constant a sampling flow rate within a measuring device as the nozzle is introduced into a chimney or a duct in response to a change in flue gas flow velocity, to thereby maintain an uniform sampling rate in the nozzle. The nozzle is connected to a dust measuring device and is inserted into an interior of an flue gas passage. The diameter of the nozzle can be changed so as to keeping sampling gas flow rate determined by the dust measuring device constant at the sampling velocity corresponding to the flow velocity of the flue gas. The flue gas sampled through the nozzle is introduced into the dust measuring device.

Abstract: A dust sampling device having a sampling nozzle is provided. The nozzle is provided with an inlets the diameter of which is variable. The diameter of the nozzle can be instantaneously changed, while keeping constant a sampling flow rate within a measuring device as the nozzle is introduced into a chimney or a duct in response to a change in flue gas flow velocity, to thereby maintain an uniform sampling rate in the nozzle. The nozzle is connected to a dust measuring device and is inserted into an interior of an flue gas passage. The diameter of the nozzle can be changed so as to keeping sampling gas flow rate determined by the dust measuring device constant at the sampling velocity corresponding to the flow velocity of the flue gas. The flue gas sampled through the nozzle is introduced into the dust measuring device.

Abstract: A particle-size distribution analyzer in a vent gas or flue gas which can be in a gas carrying line of a dust- and/or mist-producing process is provided. The analyzer comprises: a series of particle-size classifying units each consisting of a gas-ejection nozzle of an opening having a diameter different from the others and an impaction plate mounted on a revolvable turret in such a fashion that the series of the units can communicate with a suction nozzle in the gas flow line one by one successively in a decreasing order of the nozzle opening diameter; and a light-scattering particle-concentration detecting system which gives the concentration data after particle-size classification as a function of the cut-off size of the particles contained in the gas.