Why does AirBox use a 95.0% Filter instead of a HEPA Filter? HEPA Filters are rated based on the percentage of particles they retain or capture. However, the greater the retention rate the lower the flow rate. Imagine pouring water through a very fine screen. The smaller the screen size the less water flows through and vice versa. AirBox has a flow rate that is typically 2-10 times that of competitive products especially those using HEPA filters. If you do the math, at 2 times the flow rate, AirBox is 17% more effective at Net Particle Removal. At 3X AirBox is almost twice as effective and any flow rate ratio above that Airbox is practically 100% more efficient. So, the easy answer is: it’s a matter of practical application. In the Home or Office Environment, Net Particle Removal is more important than retention efficiency.
If Net Particle Removal is more important than Retention Efficiency, then why do Semiconductor and Biotechnology facilities use HEPA Filters? That is a very good question. It has everything to do with Application. Semiconductor and Biotechnology facilities are very controlled environments, to the extent there are few if any particles being generated by activity within these environments. Personnel wear Clean or Containment Suits to prevent the emission of particles from human hygiene or activity and entry and exit is through Air-showers and Airlocks. Moreover the ceiling tiles in these facilities are replaced with HEPA Filters so the air flow in these facilities is measured in Room Changes per Minute. Bottom line is that these facilities can be considered “closed or contained environments”. In the home and office environment, doors are opening as people come and go allowing allergens and other contaminants to enter, pets and people are generating particles and pathogens through all of their activities and microbes are growing despite our best efforts to maintain environmental cleanliness. Therefore, we are more concerned with removing as many particles as we can (Net Particle Removal) instead of measuring particle filter retention efficiency. IE retention efficiency matters little if you are only processing 10% of your home or Office air once every hour. Bottom line is that there is no practical way to create a closed or contained environment in a home or office application. Therefore, we focus on removing as many particles as we can as quickly as we can.
Why can’t I simply replace all of my furnace filters with HEPA filters or High Retention rate filters to keep my home or office air clean? That’s a very good thought. Actually you can do that but you do so at the expense of performance and energy efficiency. The HVAC system in your home and office is designed to condition air temperature and humidity, Therefore, flow rate and air density across the heat exchangers within your systems is critical to operating efficiency. The higher the retention rating of a filter, the more restrictive to air flow it becomes. Reference the water/screen analogy we used above. Therefore by restricting the air flow through your HVAC system, you reduce the air density and actual total mass air flow across the heat exchangers. The net result is your AC runs longer and your electric bills get bigger. Most purpose built Air Purifiers are designed with efficiency in mind. The technically advanced RadiCal impeller and energy efficient motor used in AirBox is perhaps the most efficient integrated fan module in use today. In conjunction with the AirBox flow dynamics the total package may be the most energy efficient Air Purifier available. 500 Cubic foot per minute using only 70 watts of power… you be the judge..
Is the AirBox really hand made in America? Looking at the photograph (below) taken from the bottom looking up of the AirBox interior without filters. Note the use of Bowtie Keys that attest to the Fine Craftsmanship used to construct the AirBox. The interior finish is of the same quality as the exterior. Note the rounded frame edges that provide for smooth Airflow. Finally the Deutsch Connectors used for all electrical connections are visible. These are unquestionably the finest electrical connectors available. You can’t get workmanship like this from a machine. It’s a shame these beautiful elements of construction aren’t visible from the outside. Zoom in and you can even see the “Made in Germany” embossed on the impeller hub.
(Interior of AirBox from bottom looking up.)
Why do air purifier companies always reference 0.3 micron size particles when they talk about their filter efficiency? Shouldn’t I be concerned with smaller particles in my room air as well? The answer to your question is; absolutely yes. Many particles, especially pathogens can be as small as .01 micron. The filter we use for the final stage of air filtration removes these smaller particles even more effectively than they do the 0.3 micron particles. However, most Industry standards require testing at 0.3 micron because it tends to be the Most Penetrating Particle Size (MPPS). In other words, particles between 0.2 and 0.3 are the most difficult size particles to capture and particle larger and smaller in size or more effectively captured. Therefore, if a filter is 95% efficient at capturing particles .3 micron in size, it will be more efficient at the .01 micron size. The reason for this is simply due to the fact that with these types of filters, there are multiple mechanisms associated with particle entrapment including electrostatic attraction, diffusion and Brownian motion. These 3 mechanisms are more effective in capturing the smaller particles than direct impaction from inertia. So, you can rest assured that your AirBox is working diligently and effectively at removing the full range of particles threatening the health of you and your family.
Will running my AirBox at reduced speed save on my electric bill and extend the life of the Fan Motor? Not really. We do a power draw test on every single AirBox before it leaves the Studio and find that they consume about 64 watts of power at maximum capacity (approx. 500 cubic feet per minute). That’s less than 20 cents per day for most of us. However, the fan motor will actually last longer at higher speeds. The fan’s lifetime is limited by the bearings. At lower speeds the fan motor runs hotter which shortens the bearing’s lifetime. Not to worry. AirBox uses the highest quality fan in the world specific to this application. It is expected that we will only realize a 10% failure rate at = 116,674 hours. That’s 13.3 years.
How does AirBox help protect the people in our Home or Office from getting sick? The simple answer is AirBox filters remove pathogens from the air of your Home or Office. While the size of pathogenic particles such as virus’ can be as small as 0.01 micron, the Respiratory Transmission of these particles is typically through Aerosol or Airborne droplets which are substantially larger and effectively trapped by Filters rated at 90% or better. The following is an excerpt from Virology Blog that explains how easily an airborne virus can be transmitted. It clearly illustrates the significant value of effective Air Purification systems:
“Respiratory transmission depends upon the production of aerosols that contain virus particles. Speaking, singing, and normal breathing all produce aerosols, while coughing and sneezing lead to more forceful expulsion. While coughing may produce several hundred droplets, a good sneeze can generate up to 20,000. Aerosolized particles produced by these activities are of different sizes. The largest droplets fall to the ground within a few meters and will transmit an infection only to those in the immediate vicinity. Other droplets travel a distance determined by their size. Those droplets 1-4 microns in diameter are called ‘droplet nuclei’; these remain suspended in the air for very long periods and may not only travel long distances, but can reach the lower respiratory tract. Inhalation of droplets and droplet nuclei places virus in the upper respiratory tract, where it may initiate infection.
The importance of aerosol transmission is illustrated by an outbreak of influenza aboard a commercial airplane in the late 1970s. The plane, carrying 54 persons, was delayed on the ground for three hours, during which time the ventilation system was not functional. Most of the travelers remained on board. Within 72 hours, nearly 75% of the passengers developed influenza. The source of the infection was a single person on the airplane with influenza.” Vincent Racaniello (Follow on Twitter)