In the previous article, I briefly explained the background of how the FFU (Filtration and Air Handling Unit) became the new favorite for home air purification in the past two months. Originally, it was just a detailed explanation of some friends' questions. Unexpectedly, after the post was released, more questions arose. Some friends felt unsatisfied and said that I had ended without any further explanation. What happened? In fact, I didn't plan to write in more detail at the beginning. Since everyone was so interested, I decided to elaborate on it.
Here, I will provide a simple explanation for the topics that everyone is concerned about. To make it easier for everyone to read, I will try to avoid using overly technical terms.
Currently, there are more than ten types of home FFUs on the market, and their prices vary greatly. For a 2+4ft module FFU, some cost only a few hundred yuan, while others can sell for over three thousand yuan per unit. Why is there such a big difference? Besides, FFUs are different from traditional air purifiers. What parameters do they need to pay attention to? Let me briefly introduce:
FFU, or Filter and Air Handling Unit, as the name suggests, the two most crucial components of an FFU are the fan and the filter.
The price difference between good fans and ordinary fans is more than five or six times. Just from this, you can understand where the price difference lies! I didn't plan to write in more detail at the beginning. Since everyone is so interested, I will elaborate on it.
Let's take the fan's lifespan as an example. We often use a German fan that promises a lifespan of 100,000 hours (about ten years) in a clean workshop without maintenance. So it has many supporters, including me. If you only need to use it for one or two years, a domestic ordinary fan is fine, and an FFU costing several hundred yuan is not expensive either. If you want to use it for several more years, it is recommended to use a brand-name fan. Also, I believe that although the home environment does not run continuously, frequent startups can damage the fan's lifespan. So it is recommended to keep it running continuously and purifying the air. Good fans will not have any accidents due to overheating, and you don't need to worry that the fan will accelerate damage after running continuously for one or two years - it will break down faster due to frequent startups.
What are the differences in filters?
The differences in filters are first reflected in the filter paper, and then in the folding techniques of different filter manufacturers. The price difference between domestic and foreign filter papers is also large - although not as big as that of fans. The quality of the filter paper directly determines the filtering effect. Of course, this filter paper is somewhat overused here. As long as it is not too poor and is not damaged, it can still be used at home. If you think that since the FFU has been used, the filter should be good, it is not considered too luxurious - because the overall price difference of the filter is not too big. Also, it is the folding technique. Each manufacturer has a different folding machine, and the performance of the filter sheet (media pack) produced by each manufacturer will also vary greatly, which will directly affect another parameter, the uniformity of air flow.
Perhaps what you are more concerned about is the lifespan of the filter. In high-level clean workshops, filters with an efficiency of 99.99% at 0.3um (H13) can be used for seven or eight years as normal. But you should know that the environment where they are used is already very clean - many times cleaner than our blue sky, white clouds, forests, beaches, and cacti! So for home use, optimistically speaking, it can last for one year as good as it can be! Special equipment is available for testing the lifespan of filters in clean rooms. At home, you can simply judge it by feeling the airflow. If you turn it to the maximum setting and still can't feel the airflow coming out (though the 0.45m/s airflow is not as intense as you might think), you can open the filter to take a look. I hope it won't scare you.
So it's best to choose an FFU system that allows for easy removal of the filter. This way, you can simply replace the filter. After all, the price of a single filter is much cheaper compared to the entire FFU.
Most people are still quite concerned about whether the noise of the FFU will be too loud!
The ordinary 2+4ft FFU system, at 0.45m/s (approximately 1000 cubic meters per hour of air volume), will generate around 45dBa of noise. This noise is completely within the range that humans can tolerate. In fact, at the beginning, you can adjust the wind speed to 0.35m/s, which will still provide over 700 cubic meters of air volume. The noise will be around 43dBa, making it almost imperceptible.
There are many types of noise. One type is the noise generated by the airflow itself. In fact, the noise of many air purifiers is very loud because the structure of the air outlet or inlet is not well designed, so the noise from the air outflow is very high. However, FFU does not have such a problem because the filter is always facing the outflow, and there is no so-called blockage of the outflow surface that causes noise.
In addition, some manufacturers try to hide the excessive noise of the fan by adding some sound-absorbing cotton inside the FFU - this was quite common in the industrial product industry. The author has always opposed using sound-absorbing cotton to reduce noise. Because the materials and components of sound-absorbing cotton are diverse, some can produce dust, reducing the lifespan of the high-efficiency filter, and some can emit odors, which leads to secondary pollution. Using sound-absorbing cotton to reduce noise is a rather lazy approach. In fact, responsible manufacturers still reduce noise by changing the internal flow guiding structure of the FFU, just like the exhaust pipe of a car. Its function is not only to discharge exhaust gas but also to reduce the noise generated by the car engine, so it is also called a muffler.
There are some simpler points that we can talk about later. Don't make it too long, leave some thoughts!
O(∩_∩)O~
