Use and Care Manual

2009 PORT-A-COOL® Unit Electric Models

I. INTRODUCTION

The PORT-A-COOL® unit is a fully self-contained, portable, high efficiency evaporative cooler that is

proudly made in America at our Center, Texas factory.

A. What is Evaporative Cooling?

When trying to understand evaporative cooling, it may be best to think of air as being like a sponge, in that

regard, air has an ability to absorb moisture that it comes in contact with. The amount of moisture that the air

will absorb depends on the state of the air, or specifically, how much moisture the air already contains and

the temperature of the air. If the air is warm and contains only a small amount of moisture, it will more readily

absorb moisture. As air cools, its volume decreases, and with it, its ability to absorb moisture decreases.

The term “relative humidity” describes the quantity of water in the air in relation to its total capacity. Any

volume of air at any given temperature has an ability to hold a certain quantity of moisture. If the air contains

20% of its total capacity to hold moisture, the relative humidity is said to be 20%. Whereas, a humidity of

100% indicates that the air at this temperature and pressure is holding all the moisture it can. If the air has

less that 100% relative humidity when entering the PORT-A-COOL® unit, then it has the ability to hold more

moisture, and will thus evaporate more water and cool more effectively.

When describing the amount of moisture in the air, the term relative humidity is used because the absorp-

tion capacity of air changes relative to air temperature. The warmer the air, the more absorbent it becomes,

and can consequently hold more water. That is to say that air that has a 100% relative humidity can hold no

more water vapor. However, if the air is heated, it expands, and as a result the relative humidity decreases

even though the total amount of water vapor in the air has not changed. As a result, we must describe the

level of humidity relative to its maximum capacity. Is it a 50˚F sponge or an 80˚F sponge? An 80˚F sponge

will hold more water at 50% humidity than a 50˚F sponge.

How is cooling produced? In order to evaporate water, heat (energy) is required. In fact, the evaporation

of one gallon of water requires almost 8,700 BTU’s. Where does this heat come from? The heat comes from

whatever the water is in contact with as it evaporates. This could be a hot sidewalk, your body, a tree, or

from the air itself. As the heat is removed from an object, the temperature of that object is decreased. In the

case of the PORT-A-COOL® unit, heat is removed from the air, reducing the temperature of the air.

It is important to realize that the temperature of the water does not have a great effect upon the cooling

produced by the evaporation. If you were to place a gallon of 50˚F water on a warm sidewalk, it would con-

sume 9,000 BTU’s during its evaporation, thus making the sidewalk 9,000 BTU’s cooler. A gallon of 90˚F water

would produce 8,700 BTU’s of cooling, only a 3 percent difference in the total result. This translates into a dif-

ference of less than 1˚ F in the performance of a PORT-A-COOL® unit.

The following table demonstrates the BTU’s removed from the air based on a given amount of water evap-

orated in an hour by the PORT-A-COOL® unit.

For actual temperature drops refer to Appendix A.

In simple terms, evaporative cooling is nature’s way of cooling. The PORT-A-COOL® unit utilizes the same

phenomenon, but in an extremely efficient manner.

U. S. Gallons / Hour Total BTU’s Removed

10 (37.8 liters or 8.3 Imperial Gallons) 87,000

12 (45.4 liters or 10.0 Imperial Gallons) 104,400

14 (53.0 liters or 11.7 Imperial Gallons) 121,800

PAC2K48HZ