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Misting is based on the theory of Evaporative
Cooling (or Desert Cooling), which uses the scientific principal of
Thermal Dynamics, which states that water requires energy to evaporate,
or 600 calories of heat per gram of water, and this heat is taken from
the environment. To achieve this water is forced through a very small
orifice creating a very fine mist or fog of ultra fine 50 micron water
droplets (smaller than the diameter of human hair). Once these very
fine droplets of water are exposed to the hot atmosphere, they quickly
absorb the heat present in the environment and evaporate in the
process. This quick heat exchange is known as Flash Evaporation, it
takes heat from the surrounding area, and drops its temperature by up to
35 degrees F, and consequently the air is cooled. As a by product to
cooling, there are three benefits: misting also humidifies the air,
cleans it from pollutants such as dust, pollen and smoke, and repels
flying insects. Evaporative cooling is not a new invention, it has been
used since the dawn of civilization, by utilizing a small fountain in a
courtyard, or water dripping at a window, and the wind blowing through
that offered a cool breeze, that is why people feel cool and relaxed at
locations where water is present, such as, beaches, lakes, rivers,
waterfalls, and as fog spread, temperature immediately drops.
Misting is divided
into three categories:
|
Water Pressure
|
Pressure Range
|
Max. Number of Misters
|
Comments
|
|
Low |
35 - 100 psi |
10 |
No Pump |
|
Medium |
100 - 250 psi |
30 |
w/ M.P. Pump |
|
High |
800 - 1200 psi |
80 |
w/ H.P. Pump |
- Low Pressure misting is
affected by the water pressure, and its flow rate. Normally in the
USA, house water pressure ranges between 35 psi and 90 psi.
- High Pressure misting
generates Fog, which is ideal misting, with finest mist. However the
cost is way high too, because it uses high pressure pumps, and
stainless steel tubing, and metal fittings to handle the high
pressure.
- The finer the mist, the
more efficient is the system (due to the larger surface are), and the
higher the pressure the finer is the mist produced.
Temperature Drops
|
Water Pressure
|
Pressure Range
|
Temperature Drop
|
Comments
|
|
Low |
35 - 100 psi |
25 deg. F |
Misters Only |
|
Medium |
100 - 250 psi |
30 deg. F |
Misters w/ Pump |
|
High |
800 - 1200 psi |
35 deg. F |
Misters w/ Pump |
- when misters are
coupled with fans, misting efficiency is increased.
Relative Humidity & its
Effect on Misting The ratio of the amount of moisture in air, to the
maximum amount of moisture the air could absorb at that same
temperature, is called the relative humidity. The lower the relative
humidity is, the more water could be vaporized. and the more heat
could be removed, and the better a misting system would work.The nice
thing about misting is that relative humidity is at its lowest when
the temperature reaches its peak, making misting or evaporative
cooling applicable to most geographical areas.Optimum conditions are
achieved when relative humidity is below 80%. However when RH is over
80%, cooling can still be achieved by combining misting with fans to
offer conductive cooling, and/or chilling the water to generate a
chilled mist (by icing the supply water). and that works great even
when it is really sticky outdoors.
|
Relative Humidity
|
Misting Effect
|
Temperature Drop
|
|
Above 80% |
Marginal, unless using w/ fan, and or icing
water |
10 deg. F |
|
40% - 80% |
Good |
25 deg. F |
|
Below 40% |
Excellent |
35 deg. F |
- Results vary depending
on climate conditions, wind velocity, temperature, and pressure.
Misting is not just for humans but
for animals also:
watch video
 |
Click :
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