Patent ID: 8627733

Claim:
A device for characterizing a size distribution of electrically-charged airborne particles in an air flow, comprising: a particle charging unit arranged to create the size distribution of electrically-charged airborne particles by electrically-charging airborne particles entering the device, a parallel arrangement of a first measurement section and a second measurement section, located downstream from the particle charging unit, and a data evaluation unit, wherein the first measurement section comprises: a first particle sensing unit arranged to precipitate substantially all entering electrically-charged airborne particles, and to generate a first output signal corresponding to the precipitation of electrically-charged airborne particles inside the first particle sensing unit, the second measurement section comprises: a second particle sensing unit arranged to precipitate at least part of all entering electrically-charged airborne particles, and to generate a second output signal corresponding to the precipitation of electrically-charged airborne particles inside the second particle sensing unit, and a first particle precipitation unit arranged to, for each size larger than a first particle size limit, partially reduce the concentration of electrically-charged airborne particles having said each size, the data evaluation unit being arranged to calculate, based on the first output signal and the second output signal, a particle number concentration and an average diameter of airborne particles having a size larger than the first particle size limit.