Products - Aerosol Diluters - Overview

Aerosol Dilutors - when number concentrations Aerosols are above out of instrument range

The range of products offered to characterise aerosol is able to handle very high concentrations of particles without being overloaded. However, when the numbers of particles become too high for an instrument to reliaibly measure there is only one option which is to dilute the aerosol with clean gas or air.

This dilution process must reduce the total numbers of particles, but maintain the distribution, to be useful. There are two principle options used to achieve this,

  • bypass filtration: which operates by spliting the incoming airflow in the required dilution ratio and passing the dilution gas through a filter system to form the particle free dilution flow. This cleaned dilution gas flow is then returned back to join the sample airflow, ensuring the gas streams are fully mixed so that the sample particles are distributed evenly in the diluted outlet flow.
  • ejector dilution: Fidas 200which operates by feeding a clean dilution gas usually provided as compressed air through an annular passage around an aerosol sample inlet tube, which generates a suction flow at the inlet dependent on the dilution flow and the geometry of the sample inlet / orifice. Sampling of the now diluted aerosol sample can be made at the mixed outlet port, with the excess flowing to the exhaust port. So, by setting the pressure of the dilution gas to a pre-determined value, the correct sample air flow is generated automatically by a venturi effect.

Both systems have been used for many years.

The real benefit of the ejector system is a very stable and easily verified dilution ratio in a compact device, with little variation over time like that seen in the bypass devices, which are slightly modified in performance as the bypass filters are progressively blocked. With the ejector system, if the pressure of the clean diluting gas is maintained as a constant, then the dilution ratio will also remain constant.

The VKL, KHG and DC10000 dilution systems offered by us operate using the ejector dilution principle.

Please contact us for more detailed information.