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6.2
Distances and grid layout
Dust always needs to move in form of airflows, winds, or clouds actively towards the
Dumo.
Dumo's fan accelerates the gas towards the probe only once it is very close to the
duct inside the Dumo. The fan will NOT actively pull dust particles towards it. The
pulling effect of the fan is already negligible at less than ½ inch (1cm) from the Dumo.
The further away from the source of dust the Dumo is, the more diluted the
concentration of dust will be. This means that, while the dust concentration directly at
the source point may have already reached the minimum explosible concentration
(MEC), it may be well below this critical level further away.
The time delay between the appearance of the dust at its source point and the
measuring point will be longer, and the movement of the dust cloud slower, the
further away the two points are from each other.
The more critical the installation is for worker safety, health, or explosion prevention, the
narrower the grid should be.
In case of an uncritical installation, where it can be assumed that the dust is fairly evenly
distributed and has time to spread, a grid of approximately (n) ~ 20 m / 65 ft. is recommended.
Figure 9: Installation Point in terms of air flow
Figure 10: Installation Grid
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