Port-A-Cool PAC2K16HPVSFC - Manual (Page 5)

5 2009 PORT-A-COOL® Unit Electric Models 36 2009 PORT-A-COOL® Unit Electric Models
B. Humidity and Evaporative Cooling.
A given volume of air at a certain temperature and pressure has the ability to absorb and hold a certain
amount of water vapor. If that volume of air contains 50% of the amount of moisture that it is capable of
holding, it said to be at 50% relative humidity. The higher the temperature of the air, the higher the amount of
moisture it is capable of holding. Any change in the temperature without a corresponding change in the pres-
sure results in an increase or decrease in the amount of water vapor the air can hold.
If the temperature increases without an increase in the pressure, the result is a decrease in the relative
humidity, and thus an increase in its ability to hold moisture. That is to say that in the morning the humid-
ity may be high, but as the day passes and the temperature increases the relative humidity will naturally
decrease.
The extent to which relative humidity decreases through the day can be affected by local weather systems
and proximity to large bodies of water. If an increase in temperature accompanied by a weather system
containing moisture moves in, then the drop in humidity will not be as great. Nevertheless, the fact remains
that relative humidity does drop as air temperature increases. In fact, for every 20˚F rise in temperature, the
moisture-holding ability of air doubles. For instance, if the temperature of the air was 70˚F and the relative
humidity was 100% at 5 a.m., and the temperature increased to 90˚F at noon, the moisture holding ability of
the air would double.
As a result, the air would now be holding only half of the moisture it is capable of holding, and the relative
humidity of the air would drop to 50%.
The hotter the day, the drier the air becomes, and the more cooling that can take place through the evapo-
ration of water. This means that when the day gets hot enough to require cooling, the relative humidity will
be much lower than in the morning and will allow an evaporative cooling device to work more effectively.
Since any evaporative cooling device must evaporate water to achieve cooling, more water vapor is put
into the air. As the ambient relative humidity increases, it becomes more difficult to put moisture into the air.
The efficiency of any evaporative cooling device is directly related to its ability to evaporate water (cooling
the air) at a given relative humidity. A unit with low efficiency will cool only at low relative humidity levels,
while a unit with high efficiency can achieve effective cooling at much higher humidity levels.
C. Evaporative Cooling and the pORT-A-COOL® unit.
The PORT-A-COOL® unit is the state-of-the-art, high efficiency, portable evaporative cooling system that
utilizes high efficiency KüüL® brand, rigid cooling media, manufactured with the patent pending “thru-cure”
™ process.The PORT-A-COOL® unit’s unique patented housing enclosure, along with the KüüL® brand
high efficiency cooling media, allows the unit to cool effectively in very high relative humidity conditions.
Conditions that other portable evaporative cooling devices, such as the old style “swamp coolers”, cannot
approach.
The public has an initial tendency to equate the PORT-A-COOL® unit with the “swamp cooler,” types of
evaporative coolers and, in reality, the only thing that they have in common is that they are both evaporative
coolers, much as the 1973 model automobile and 2003 model automobile are both cars. The key to efficient
evaporative cooling is using a specially designed, high efficiency, rigid cooling media contained in a properly
designed housing to insure effective directing of the air over the water saturated media at the proper velocity.
The PORT-A-COOL® unit has incorporated all of these features and more.
As explained in PART B of this section, the effectiveness of the PORT-A-COOL® unit is best appreciated when it
is above 85˚F and below 75% relative humidity. By the time the outside temperature reaches 85˚F, the humidity is
almost always below 75%. Generally, as one goes up, the other goes down.
For actual temperature drops refer to the charts of Appendix A.
pAC2K36HZ