下載次數(shù)：393次 瀏覽次數(shù)：707次發(fā)布時間：2017-06-05 13:48Optical particle counters show a maximum measurable aerosol
concentration due to their operating principle. If this limit is exceeded
major measurement errors cannot be excluded, for example because of
coincidence. In case of testing of laminar flow boxes or clean rooms
according to VDI 2083 measurements of high upstream concentrations
are stipulated. Conventional clean room particle counters are unable to
measure at such high concentrations.
By placing the dilution system HDS 561 before the particle counter the
aerosol concentration can be reduced by a factor selected by the user.
Thus, the required upstream concentration of more than 106
particles per
cubic foot can be diluted to a concentration which is within the measuring
range of the particle counter.
The High Dilution System HDS 561 is designed to dilute aerosols with an
adjustable dilution factor. Due to its accuracy a high degree of
reproducibility is guaranteed. The adjusted dilution factor is shown on the
display.
For a certain dilution factor the appropriate number of particles is
removed from the aerosol without occurring change in the particle size
distribution.
The device is easy and safe to operate. It is flexible to use and can be
utilised in combination with different particle counters.
The dilution system HDS is designed for a specific volume flow from
2.8 l/min to 100 l/min. Each device is calibrated by the manufacturer for a
fix flow rate. The range of adjustment of the dilution factor depends on
the current total volume flow and capillary type. For example, for a
volume flow of 28.3 l/min (1 cf/min) dilution factors from 6000 to 100000
can be adjusted (for more details see chapter “Options”).
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