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The Secrets Behind Kubota's Innovative Commercial Air Humidifier-Purifier for Large Spaces

Cleaning the Air with Water

With the heightened awareness of indoor ventilation brought on by the COVID-19 pandemic, the importance of air quality is being reevaluated. One sign of this is that sales of air cleaners at home appliance retailers in Japan were up 18% in February and March 2020 over the previous year (according to research by GK Japan). This consciousness is spreading beyond homes to offices and other public spaces that are used by large numbers of people. Kubota's commercial air humidifier-purifier has also experienced sharply higher demand.

In this article, we talk to the engineers who were involved in the development of the attention-getting air humidifier-purifier and trace the events that inspired its creation.

Kubota’s Commercial Air Humidifier-Purifiers Handle Large Spaces with a Single Unit

Our commercial air humidifier-purifier was created with the concept of "cleaning the air with the power of water to purify and humidify the air.” Developed by applying technologies used in industrial clean rooms, it captures airborne viruses, mold and other particles and decomposes them using slightly acidic electrolyzed water*1 generated inside the unit.

  1. *1.This functional fluid provides both strong sterilization capability and high levels of safety. It is expected to be effective for controlling a wide range of viruses and bacteria including the norovirus, for which alcohol disinfection has little effect.
  • Kubota’s commercial air humidifier-purifier simultaneously sterilizes, humidifies, deodorizes, and purifies (removes dust from) the air in a large space with a single unit.

One advantage of this product is that the slightly acidic electrolyzed water generated inside the unit can be extracted and used for various purposes. This feature and its cost benefits have earned Kubota’s air humidifier-purifier an excellent reputation, leading to its use in nursing care facilities and clinics as well as cafeterias and rest areas in offices and factories.

With both demand and attention on the rise, it is being put to work in lots of areas. What is the story behind its creation? We spoke with Taku Aizawa of the Precision Equipment Engineering Department who oversaw the product’s development.

The Challenges and Trials of Creating a Product Unlike Any Other

What inspired the creation of the commercial air humidifier-purifier?

“I joined Kubota in 1998, working as an engineer for water and sewage treatment. In 2007 I was transferred to what was then the Air Conditioning Division (now Kubota Air Conditioner, Ltd.) to explore new business opportunities. Given the SARS outbreak of 2003, the H1N1 influenza virus outbreak of 2009, and air pollution from PM2.5, there was increasing demand for home air purifiers. However, there weren’t any products designed for public spaces or other large areas. I thought the waves of this trend in appliances would eventually reach the commercial and large-space realms, and that was the initial inspiration.”

  • Taku Aizawa joined Kubota in 1998, starting his career as a water treatment engineer. Since 2011, he has supervised product planning and development for the commercial air humidifier-purifier.

What kinds of technology are used in Kubota’s commercial air humidifier-purifier?

“Kubota Air Conditioner develops and manufactures air conditioning systems that are used in the clean rooms of LCD panel and plasma display factories. We accumulated experience and knowledge with the Air Washer technology used in those, and I thought that could also be applied to personal air conditioning. Air Washer is a technology that sprays a mist of pure water to remove sulfur oxides (SOx) and nitrogen oxides (NOx).”

  • Air Washer technology is used in industrial clean rooms that require advanced levels of air purification.

What was the greatest difficulty you faced in its development?

“This product was based on an unprecedented idea, so it was very difficult to create a concept for it. Ionic air purifiers were already the norm at that time, so we received comments such as, “Why did you decide to use water instead of ions?” “Why use slightly acidic electrolyzed water?” “You should make it small so it’s easier to sell.” We focused on developing a product that would address all of these concerns at once while being technologically feasible.”

Creating a completely new product while convincing everyone around you must have been a difficult task.

“Before developing this commercial air humidifier-purifier, I was involved in making a grain dryer that dried harvested grain so it could be preserved longer. For that project as well, we brought together the wisdom and experience of new team members with differing backgrounds, and we created a new product through the process of diffusing and converging their ideas. I think I can say that I’m utilizing the experience from that project.”

Were there any other challenges?

“Making the unit’s housing as compact as possible was also a challenge. The Air Washer requires a certain amount of space where the air and water come into contact when the water is sprayed, which we call a humidification distance. We had to work carefully to ensure this distance while making the unit a compact size.”

This ability to achieve both a compact unit size that can be installed in public spaces and the functionality of the Air Washer technology is where Kubota’s expertise comes into play. However, just making the unit small was not enough. A design was required that would blend well with existing offices, stores, and other spaces where our commercial air humidifier-purifier would be placed, but it also required water supply and drainage work for installation, so a host of other specifications were required.

  • Another feature of the commercial air humidifier-purifier is its natural design that does not disrupt the ambience where it is installed. Depth was prioritized over width to keep it from obstructing the flow of traffic.

The Combination of Air Washer and Slightly Acidic Electrolyzed Water Makes It Unique

Air Washer, which sprays a mist of water with almost zero impurities to remove dirt, is a technology cultivated by Kubota Air Conditioner. To apply this technology to this commercial air humidifier-purifier, which uses tap water, an additional water sterilization capability was required. This is the reason slightly acidic electrolyzed water was adopted, and the combination of this type of water with the Air Washer technology would become the key feature of the product.

Various technologies other than slightly acidic electrolyzed water were considered during the development process. These included disinfectants such as ozone and chlorine dioxide, and disinfecting methods using irradiating light such as ultraviolet rays. Why did the development team choose slightly acidic electrolyzed water?

What are the reasons for choosing slightly acidic electrolyzed water to give the water its sterilizing capability?

“What we prioritized was safety for personal use. We wanted to conduct a survey on needs for commercial air humidifier-purifiers in public spaces, so we interviewed construction and design firms that deal with air-conditioning equipment. Everyone working in the building equipment field said the most important thing was safety. The method that ensured both high levels of safety and sterilizing capability was to use slightly acidic electrolyzed water, which contains large amounts of the excellent sterilizing component hypochlorous acid and is approved as a food additive by the Ministry of Health, Labour and Welfare.”

Does this combination of Air Washer and slightly acidic electrolyzed water help make it highly distinctive as a Kubota product?

“Yes, it does. Our commercial air humidifier-purifier circulates water inside the unit, and when water is being circulated while air is being purified, bacteria and dirt in the air will be taken in, causing the water to get increasingly dirtier. That is why we added slightly acidic electrolyzed water to decompose the bacteria and dirt in the water and reduce the amount of water to be discarded. Making it so the water can be circulated and used by adding just a little slightly acidic electrolyzed water is very much a unique Kubota technique. Also, mixing in more slightly acidic electrolyzed water would improve sterilization, but it would also produce a stronger odor, like a swimming pool. We conducted a series of tests and tracked changes in bacterial counts with different concentration levels and operating times to determine the best level of concentration. We placed a prototype unit in the Kubota Air Conditioner offices for about a month and surveyed employees each day while adjusting the operating conditions. We listened to actual reactions from people in the office while we verified the odor, operating noise, the distance of the airflow, and other factors.”

This capability to extract slightly acidic electrolyzed water is one of the main advantages of Kubota’s commercial air humidifier-purifier. How did this become possible?

“We had the idea for extracting slightly acidic electrolyzed water from the beginning. However, we were not sure if there was a need for this feature in consumer applications, and the technological hurdle was high, so we did not implement the extraction feature at first. Later in the process, after doing market research with our sales department, we found cases in which long-term care health facilities, hospitals, and pet stores were extracting the slightly acidic electrolyzed water and using it for surface sterilization. This kind of water sells for about 300 yen per liter for commercial use and about 1,000 yen a liter at drugstores, but when taken from our commercial air humidifier-purifier it could be used for as little as one or two yen per liter*2. We decided that this dramatic cost advantage could become a selling point, so we added the extraction feature. This and the automatic water supply and drainage feature have been very well-received at places have implemented the devices. One clinic had been using multiple air cleaners and faced the hassles of having to add water to them and deciding who would do the work. We were told that implementing our product eliminated those problems and made their lives much easier. I’m simply delighted to know that the features we installed are helping people.”

  1. *2.Total cost for electricity, water, and chemicals when one liter of slightly acidic electrolyzed water is generated with Kubota’s commercial air humidifier-purifier.

Mr. Aizawa originally joined Kubota to work as a water treatment engineer. He never imagined that he would be transferred to Kubota Air Conditioner to make this commercial air humidifier-purifier, he says with a smile. Managing water quality in terms of odors and sterilization capability through repeated testing goes back to Aizawa’s roots as an engineer working with water.

  • The slightly acidic electrolyzed water can be extracted easily and is used in a wide range of applications, including sterilizing tables and preventing bacteria at water drainage points.

The Engineers Envision the Future of the Commercial Air Humidifier-Purifier

The Sales Department has submitted a variety of requests regarding Kubota’s commercial air humidifier-purifier, including support for IoT features. While there have been some calls to make the unit smaller, Mr. Aizawa sees things from a different perspective.

What are the prospects for functional additions and improvements in the future?

“We have been asked about making the product smaller, but I actually think it would be better to make it bigger. That’s because it has to be able to agitate the air in large spaces. If the unit is small, it creates less airflow and can only circulate the air around the housing. To get a better agitation effect, we need to make the housing larger so it can create greater airflow. Just making the unit larger could make it inconvenient to use, so we’re thinking of ways other than increasing its size. I think that sort of opposite approach may be necessary.”

Are there markets you wish to expand Kubota’s commercial air humidifier-purifier in the future?

“One market is offices. There is a growing awareness of business continuity planning (BCP) and health management nowadays, so we would like to contribute to creating environments where office workers can work comfortably and with peace of mind through our commercial air humidifier-purifier. We’re actually getting a greater number of inquiries from offices now.”

Finally, what are your goals and hopes for the future?

“The combination of Air Washer technology that cleans the air with water and slightly acidic electrolyzed water, along with the cost benefit gained through the ability to extract the slightly acidic electrolyzed water, have established our commercial air humidifier-purifier as a unique product not available from any other manufacturer. I take great pride in this. We have delivered about 700 units to about 260 clients throughout Japan. I hope we can expand our business by increasing the number of units installed in offices and contribute to creating spaces and communities that are resistant to infectious diseases.”

  • Mr. Aizawa smiles as he speaks about the future prospects for Kubota’s commercial air humidifier-purifier.

Kubota started as a casting company in 1890 and began making commercial cast iron pipes for waterworks in 1893. Since then, Kubota has been involved in many water-related concerns, producing valves, pumps, water treatment systems, and septic tanks.

Kubota’s air conditioning-related operations began with the establishment of Kubota Trane, Ltd. (now Kubota Air Conditioner), a joint venture with American air conditioning manufacturer The Trane Company, to meet the needs of facility air conditioning that accompanied the construction rush during Japan’s rapid economic growth period. About half a century later, a one-of-a-kind commercial air humidifier-purifier was born, packed with the wealth of technologies and expertise that only Kubota, with its many years of experience with water, could provide.

In Kubota’s commercial air humidifier-purifier, one can see the uniquely Kubota approach to manufacturing: finding a social need tailored to the times in a market for humidified air cleaners for public spaces that did not yet exist, addressing this need with sincerity, and taking on solutions. When asked about expanding the product market outside of Japan, Mr. Aizawa says that he plans to fully establish the air purifier business domestically first and then take gradual steps abroad.

From Kubota Press (Japan)
Kubota Press (Japan) is Kubota’s owned media that covers the fields of food, water, and the environment from the perspectives of people, technology, and communities to convey where Kubota is today and give a realistic picture of where we work.

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