Operating principle

Based on well-known ELPI™ technology , device consists of a corona charger complete with on-line particle density measurement, and an inertial 6-stage impactor with electrical detection.

A diffusion charger is used to give precisely determined charge to all measured particles. Charge level is close to saturation charge level for each particle size. After charging region a static electrical field is used to deflect smallest particles to the charger mobility electrode; an electrometer is used to measure this current. This construction is used as a particle mobility size analyzer.

After charger particle size classification is accomplished in a 6-stage inertial impactor. Sensitive electrometers are connected to impactor collection sensors and particles impacting to a corresponding collection plate generate an electrical current for that electrometer. This current is proportional to the amount of particles in each size range. Combining the particle mobility size information from the charger and aerodynamic size from the impactor enables calculation of the effective density of the particles required for conversion from measured current values to particle number and mass concentration.