Bipolar Discharge System

Fig. 1: Functional principle of corona discharge

A dust or liquid aerosol is supplied at the aerosol inlet. The particles in this aerosol have to be discharged. The mixed air inlet is fed with dry, pressurized air. The mixed flow air is passed through two ionization chambers. In these chambers, the air is enriched with ions from the corona discharge with positive and negative high voltage. The aerosol air stream and the mixed air enriched with ions are mixed in a small mixing chamber. The charges of the particles in the aerosol are neutralized by the ions in the mixed air. This takes a certain time. That means, the complete discharge only occurs in the volume after the CD 2000 outlet (e.g., in the tubing system or the upper part of a filter holder). An approximate value for the dwell time is 0.5 seconds. A satisfactory discharging effect was found in configurations that ensure a dwell time of at least 0.2 seconds.

Attention

Many standards, e.g., EN 779 for room filters, require a discharge unit.

Comparison measurement

Fig. 2: Fractional separation efficiency with and without CD 2000

With a filter medium or filter (exception: Electret filter medium or Electret filter), the fractional separation efficiency is usually measured higher without a discharge unit than with one.