O
PERATION
M
ANUAL
VKL
10
/100
V
ERSION
V005-06-2020
8
4. Operating Principle
4.1. General Information
The purpose of a dilution system is, first of all, to lower the concentration of a given aerosol
while leaving the particle size distribution of the aerosol unchanged. In using the dilution
system VKL, this aim is reached by homogeneously mixing a definite amount of clean air with
a definite amount of aerosol. The ratio of amount of aerosol and clean air is predetermined
and stable. The external clean air flows through an ejector-nozzle system. This causes an
underpressure which sucks in the aerosol. Consequently, the dilution stage is a self-sucking
system.
One single dilution stage VKL 10 has a dilution factor of 10. If a higher dilution factor is
required, several units may be connected in series. Such a cascade connection permits for
example the dilution of 2 liters of aerosol with only 72 liters of clean air by a factor of
10,000.
The dilution factor of the VKL 100 depends on the volume flow rate of particle-free air and
varies between 150 and 90. A dilution factor of 100 is achieved in one unit with the same
clean air consumption compared to two VKL 10.
However, the application range of the VKL 100 is limited compared to the one of the
VKL 10:
- highly concentrated dusts with mass concentration > 100 mg/m
3
and
particle size > 2 µm may block the capillary tube
- liquid particles with a diameter > 1 µm may break up due to shear forces in the flow
- the dilution factor depends on the clean air flow