In this part of Full HVAC Course, We will learn about Smudging in Air distribution..

Smudging in Air Distribution

Introduction:

The first thing i want to talk about is smudging in air distribution for high-velocity air systems (HVAS), or any air distribution system really. I'll start out talking about HVAS's, since they're what everyone knows about. Then we'll move onto some basic concepts revolving around how the air moves and gets distributed throughout the room. That way we can apply those to what I'm going to say later.

What is High Velocity Air Systems?

High velocity air systems are basically a way to distribute cold air (or hot air) to specific zones throughout a building using fans. Basically, the fan pushes the air through a tube (called an air handler) and then splits off into different tubes that go towards each zone. In order to do this, you need two things; airflow and temperature. If you don't have enough airflow, you won't get enough displacement of air. To put it simply, airflow is just the amount of air being moved per second. You can measure airflow by putting a flow meter on the input side of the air handler and measuring the actual volume of air coming in. Temperature is measured by placing thermocouples in various locations throughout the room. By taking these measurements at different points, you can calculate the exact temperatures of the air in each zone.

How does smudging work?

When you smoke, you create smoke particles. These particles have a density much higher than that of the surrounding air. When you blow smoke through the air, it creates a layer of smoke above the existing particles. This is called a plume and acts essentially as a cloud, floating the particles slightly above their current location. Because of the difference between the density of smoke and the density of air, the smoke is displaced upwards away from its initial position. This means that even though the smoker may not physically move anywhere, the smoke travels across the area where he/she was standing.

This effect can be seen in a pretty simple experiment. Take a bowl full of water and add a couple drops of food coloring. Now, hold your hand over the top of the bowl and blow into it. As long as you keep blowing, you'll notice that the color slowly rises.

Concept 1: Displacement

To understand this concept, you need to know something about physics. There are three types of movements, namely translation, rotation, and momentum. Translation refers to moving the object in question in a straight line. Rotating involves rotating an object about a certain point. Momentum is movement due to force.

These three terms represent the three ways we interact with matter, as well as movement. Translation makes an object move in a straight line. Rotation causes an object to turn around a fixed axis. Momentum is the result of a force acting on an object. When an object is placed in motion, its momentum stays constant until the force causing the change in momentum stops.

So now let's look at our example. Since the bowl of water is resting on a surface, it is stationary and cannot translate. So, if we take the bowl of water and place it on a table, it will begin translating.

If we were to rotate the bowl of water, it would stay still because it cannot rotate. However, if we were to take the bowl of water, spin it around, and drop it back down on the table, it would cause the water to translate. We've proven that translation movement caused by an external force.

Now let's look at what happens when we use momentum. Imagine a person pushing a bowling ball along the ground. The ball begins translating and continues to move forward at a constant rate. Eventually, the person holding the ball lets go, causing him/her to stop pushing the ball. The momentum of the ball remains constant and continues to move forward.

Now, let's think about what happens when we use force to move something. Think again about someone pushing a bowling ball. This time, however, imagine the person pushing the ball holding a string attached to it. The string extends out behind the person, pulling the ball. Again, the momentum of the ball begins to translate. But, once the person releases his/her grip of the ball, the string pulls the ball backwards. The momentum of the person and the string pulls the ball back, causing them to stop. Once again, momentum stays constant.

Smudging in air distribution

Air distribution systems generally consist of ductwork, fans, vents, filters, etc., that move air throughout a building. In general, these components should be kept clean and free of contaminants such as smoke, odors, mold, mildew, dirt, dust, hair, etc. There are two methods of achieving this goal. One method is keeping the area around the system clean, while the second method involves using an odor-neutralizing product called smudge bombs (or “smudge sticks”). Both of these methods work well; however, they have different advantages and disadvantages.

Keeping the area around the system cleans and neutralizes the air quality. This method is good at avoiding the buildup of static electricity in the ductwork. Many companies use this method for their regular cleaning schedule.

However, since this method does not allow for quick changes in air flow, it may be hard for a person who wants to change airflow direction in a specific area.

Using a smudge stick makes it easier to quickly redirect airflow without having to clean the entire room first. Using this method, a person only has to apply a small amount of chemical to the filter and then blow out the fan. Once done, the smudge stick will disperse the chemicals evenly across the whole room. For example, if someone wanted to create a negative pressure environment, he/she could simply place the smudge stick on the floor near the exhaust vent. Afterward, the air would pass over the chemical in order to prevent the spread of any odors.

Since the smudge stick contains chemicals that neutralize smells, it works best when placed directly above an exhaust vent. Ideally, you want to keep the smell away from the building for the longest possible time and in a controlled manner. This means that you do not want to contaminate the rest of the space with the smell that comes from the exhaust vent and then disperse them throughout the rest of the building.

For this reason, it is recommended that the user position the smudge stick close enough to the exhaust vent, but not in contact with the actual vent cover. If the chemical gets on the vent cover, it will block its functionality.

Finally, you need to understand how the chemicals react. For instance, if the chemistry reacts with ammonia, the chemicals won't work as efficiently. Therefore, you need to know what type of chemicals you are dealing with before attempting to use them.

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