| The
secret to the superb dispersion and deposition
qualities of Corona fog relates to the small size
of the fog droplets. A Corona fogger can
produce droplets as small as 0.3 micron in
diameter. Until they ‘age’ and grow
significantly the droplets are small enough to
remain unaffected by gravity. Instead, they move
up, down, and sideways in random fashion (referred
to as Brownian Motion), dispersing
readily throughout an enclosed area. |
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| Turbulence
results when droplets pass over rough surfaces
and encounter obstructions in their pathway.
Brownian motion and
turbulence vary with droplet size. The smaller
the droplets, the faster and more evenly they
disperse. Natural or fan induced air movement
will also boost the rate at which the fog spreads
to the outer edges of a large enclosed area.
Every object is fully shrouded and impacted from
all angles by a mass of tiny droplets.
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- Dispersion, penetration
and reach of droplets of different
- size from a given
amount of fluid
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Target
collision and penetration advantages are even
more significant because, for a given amount of
fluid, the number of droplets increases quite
dramatically, actually as the cube of any
decrease in droplet size. Smaller
droplets disperse to cover far more surface area
than droplets of larger size but equivalent total
volume.
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| Or, as illustrated in the chart
below: As droplet diameter decreases,
a given amount of fluid is represented by a
disproportional greater number of droplets that
have a similarly greater combined contact
surface.
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| As droplets collide they
may merge and become larger. Coagulation
modifies the droplet distribution,
reducing their number and increasing
their mean size. This process will
accelerate with any ‘natural’
or fan-induced air turbulence in the
targeted area. Gradually,
more droplets grow to sufficient size
(larger than 1 micron) to be affected by
gravity, encouraging their descent and
causing them to deposit more extensively
on horizontal surfaces
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- The Corona
fogger consistently
emits small droplets to replenish the
target area. As the number of
‘older’ and larger droplets
grows the proportion of smaller droplets
will of course be reduced and so will
their longevity – i.e. the mean
droplet size will increase. However, the
target area will have been exposed to a
larger number of smaller, more deeply
penetrating droplets with a long survival
or ‘hang’ time, than had the
initial source droplets been larger.
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Page by JS. '03
Last updated on
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The unique qualities of Corona fog
reach
the face of obstructions