DEMC - Differential Electrical Mobility Classifier

DEMC 1000 | DEMC 2000 — Differential Electrical Mobility Classifiers for selection of particles in the range of 1nm to 1000nm


The DEMC 1000 / 2000 is a classifier that is able to separate aerosol particles from a polydisperse feed according to their electrical mobility and output a monodisperse aerosol from its outlet port. The two ranges available offer precise classifiaction in the range from 1 - 1000 nm in 64 channels per instrument.

The Palas DEMC is able to be universally connected to CPC's and aerosol electrometers from other manufacturers.

The instruments operate using the deviation produced by a radial electrical field generated between two concentric conductors with the aerosol flowing through the gap between them. By balancing the electrical field with the aerodynamic drag force in a laminar air flow, particles are diverted as they flow through the annular gap until, at the top of the instrument the particles selected by their electrical mobility will flow through a small slit and into the outlet flow.DEMC Operation

Particles larger than the size range of the instrument are removed by impactors at the inlet to the instrument. To ensure that all particles entering the instrument have reached a normalised charge level, a low level Kr-85 source is used to produce a Boltzmann equilibrium charge level on the inlet aerosol.

The DEMC is controlled via a graphical user interface which offers lin / log display of measurement values and data management through an integrated datalogger.

Technical Parameters

  • Particle Size Range:
    • DEMC 1000 dp = 1nm - 350nm
    • DEMC 2000 dp = 5nm - 1000nm
  • Number of Size Channels: 1 - 64
  • Flow rates:
    • Sample - 0 - 4 l/min
    • Sheath - 0 - 8 l/min
  • Impactor: nozzles for 3 different cutoffs
  • Operator Interface: Touch Screen Display 800 x 480 pixels
  • Processor: 1.6 GHz Intel Atom with 2GB Compact Flash
  • Communication Interfaces: USB, WLAN, Ethernet, RS232/485
  • Power Supply: 115/230 V ; 50/60 Hz
  • Control Unit Dimensions: 33 x 38 x 24 cm (H x W x D)
  • Column Dimensions: 15 x 57 cm (diameter at base x H)
  • Weight:
    • Control Unit: 12.9 kg
    • Column: 9.3 kg


  • Calibration of CPC's
  • Highly monodisperse particle source
  • System component of a SMPS

Particular advantages

  • User can select any size within the specified size range
  • DEMC can connect to many different manufacturers CPC to form a new SMPS
  • Continuous fast scanning operation
  • Intuitive user interface with measurement value display
  • Integrated data logging
  • Supports network connectivity

Please contact us for more detailed information.