Real-Time Cascade Impactor for Gravimetric Measurement of Fine Dust


Basically it is known to integrate quartz crystals into impaction zones of cascade impactors so as to continuously determine the gravimetric mass which is accumulated in each of the stages. Doing this it is inter alia necessary- that each impaction zone has a defined distance to the classifier nozzle- that the crystals oscillate freely- that the change of resonance frequencies due to the accumulated mass can be determined quickly and reliably- that the mass accumulation on the crystals is radially as symmetrical as possible- that the influence of the flowing gas to the quartz oscillation is considered correct.It is also useful if the crystals can easily be interchanged or replaced by others. The granted European patent is particularly directed to crystal holder. This holder guarantees- that crystals can be easily interchanged or replaced by others- that the distance of the crystal to the classifier nozzle takes a fixed value independently of crystal thickness- that crystals can oscillate freely and- that thin crystals with high resonance frequency can be used.Radially symmetrical accumulation is achieved by appropriate arrangement of a plurality of individual holes in the classifier nozzles. Applications: Environmental monitoring


1) Parallel size-selective measurement- real-time measurement- measurement of ultra-fine particles (about 0.06 µm in diameter PM 0.1) - directly gravimetric measurement- analysis of sweep signals recovers information about inelastically coupled masses- continuous measurement allows for detection of rebounced particles and for corresponding correction of measurement signal- high sensitivity (about 10 ng)- adaptation of sensitivity by use of different quartzes 2) Low cost of ownership: no change of filters no disposables user friendly operation potential for maintenance free operation

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