The first two posts were written to provide an introduction to the basic knowledge of FFU for people outside the circle. Of course, the readers are not only outsiders but also insiders. The insiders' initial reaction to the use of FFU in the civilian sector was similar to mine when I first heard about it. Some insiders who wanted to enter this market also had a bit of complaint: The situation is already that bad, you've explained it too simply. How can we make more money in the future?

Here, I sincerely apologize. In fact, FFU is just that simple. You want to sell it at a price of tens of thousands of dollars per unit for a purification device, it's still quite difficult. In fact, for many things, it's enough for the merchants to earn a reasonable profit. I believe that any excessive profits can only be sustained for a short period of time and are unlikely to last long. Some air purifiers once had excessive profits for a while because there was a period of irrational consumption. However, the market always has high-end and low-end segments. It's impossible for a single brand to monopolize the majority of the market. You might consider adding some more attractive and high-tech elements, making it more appealing as a luxury product. There will definitely be wealthy people who like it. Or add some gimmicks. For example, during the time when Mi Yue's youth was collecting herbs, they once touched the iron ore used to make the box of this FFU. So the price must be very high!

Now let's talk about the other several topics that everyone is concerned about recently:

1. Will the glass fibers in HEPA (High Efficiency Particulate Air) be emitted? Are they harmful to the human body?

First, let me clarify: Currently, the filter paper used in industrial cleanrooms for high-efficiency filtration in the market, whether high-end or low-end, is mostly glass fiber filters. Generally, glass fibers are harmful to the human body. The question is whether HEPA can emit glass fibers that are harmful to the human body.

This involves the microscopic structure of glass fiber HEPA. I won't go into detail. Imagine the following two simple questions:

1. If there are constantly many glass fibers being blown out from the HEPA, can the clean workshop created by using these HEPA still be used for particles as small as 0.3 μm or even 0.12 μm, which are not allowed to exist individually?

2. Currently, millions of industrial workers are working in clean rooms for years and months. If the HEPA can emit glass fibers, then the lungs of these industrial workers will definitely be severely damaged. But that's not the case.

So the efficient glass fibers of HEPA will not be emitted. According to relevant data, the glass fibers that are more harmful to the human body are those in the range of 1-5 μm. So there is no need to worry about this aspect of HEPA.

2. Energy consumption

When talking about energy consumption, we must say again about the fan. There are two main types of fans used in FFU on the market: AC (Alternating Current) and EC (or DC, Direct Current). For EC fans, there is no need to worry about what kind of power supply is provided. Ordinary household single-directional AC power is fine. You don't need to bother to understand how it rectifies internally. Just buy a professional book about motors at home and study it for a few months and you'll become an expert on fans!

Compared to AC fans, in the same operating conditions, the energy consumption of EC-FFU is about 60% of that of AC-FFU. Why this is the case, you don't need to understand it. Just know it. For an ordinary 2+4ft EC-FFU, the energy consumption is definitely less than 100W. A good fan, such as the German fan I'm using, at an initial speed of 0.45 m/s, is around 60W. While in the same conditions, the energy consumption of AC-FFU may reach 150W. At the same time, the noise of AC-FFU will be 1-2 dBa higher than that of EC-FFU.

Is there no drawback to EC-FFU? Yes, you guessed it right. Expensive!

3. Can FFU remove gases?

I know that people will ask this question. Currently, the FFU is basically equipped with an unpartitioned high-efficiency filter. Their purpose is to remove particles, but they have no effect on gas molecule pollutants (AMC). Gas molecule pollutants are smaller particles - perhaps not called particles yet. Currently, all mechanical filtration methods cannot remove them, so only porous substances (such as activated carbon) can be used for adsorption. We call this the adsorption principle.

So if there is an unpleasant smell at home, or if you want to remove the smell along with it, the current FFU does not have this effect. It is more appropriate to buy an air purifier - that one has more comprehensive functions.

Of course, with such advanced manufacturing, if there is a demand, someone will always come up with a way to increase the chemical filters.

IV. Can HEPA filters be extended in lifespan?

Previously, I repeatedly pointed out that using this thing at home is indeed a bit overkill. The direct result of using a large tool for a small task is that particles that are not harmful to the human body are all filtered out - this is actually unnecessary. Of course, I believe that if FFU is widely used in the civilian sector, some merchants will consider adjusting the filter level from H13 to H10 or even lower F9 level. That would be sufficient to filter out 99.9% of PM2.5, and the filter lifespan would also be extended a little. Here is an internal tip: Currently, the filter paper of H10 or F9 is used much less than that of H13, so it is actually more expensive than H13 filter paper. So for now, most people still use H13 filter paper more.

However, if a G3 or G4 primary filter material is added to the inlet of the FFU, then the lifespan of the HEPA filter will also be extended a little. The primary filter material can filter out large particles that should not be filtered by HEPA, reducing the burden on HEPA. Each FFU manufacturer has such primary filter cotton, which is very cheap and can be replaced every half a month.

V. Can HEPA filters be reused? How to handle them?

HEPA filters cannot be reused. The filter paper in the microscopic domain is not a thin sheet, but a jungle of glass fibers. Many particles remain in it due to various filtering principles and no longer see the light of day. To retrieve them again, it is really difficult.

The home environment we use is not for substances that are radioactive or viral in nature. So HEPA can be directly discarded for treatment (not thrown out of the window, but placed in the garbage bin). Because we only fix the "smog" in the air that is floating in the air in the filter, the "smog" in the air has already formed our body's armor, so the fixed "smog" is not so terrifying!

Let's stop here. If there are other common questions, I will write a sequel!