Presence of nano particles is determined by measuring differences in gas flow speed, pressure and temperature between raw gas passage and secondary gas passage

摘要

Determination of the presence and quantity of selected nano-particles in a gas against time involves the combined use of a raw gas first passage and a second particle-free gas passage. The process measures differences between the two passages of gas flow speed, pressure and temperature. One or all of these measured values is used as the basis for automatic calculation of raw gas concentration/dilution, or for frequency control of the raw gas transport and maintaining the raw gas dilution at a constant value. The gas flow rate through the measuring passage is raised or lowered by a pump. The measuring passage temperature is maintained above the effluent gas dew point by a combination of a heater and thermal insulation. Larger particles (micron range) are removed from the flow of raw gas prior to entering the raw gas passage, by using a heated separator, such as an impactor or cyclone separator. The measuring passage has a main inlet closure and a secondary inlet for the introduction of a calibration aerosol or gas. An Independent claim is included for an assembly for use in the above method.