Both air filtration and purification are related topics, but different in the fact that filtering of air is a method of capturing or trapping particulate that is air borne whereas purification would best be described as the neutralizing of those items or gases in the air that are harmful and may not be visible to the human eye such as viruses, odors and bacteria. There are chemicals that can eliminate germs and viruses on surfaces and in the air, but you will quite often find the chemical odor is more harmful or unpleasant than the problem you are trying to eliminate. The old method of getting rid of odors and dust was to exhaust the air to the outdoors with the use of fans. As mentioned in other sections on our site, the exhausting of air with even a small residential exhaust fan results in the infiltration of untreated outdoor air back into the space. Products discussed below are available for both residential and commercial / industrial applications.
Filter efficiency is based upon the size of particles that will be arrested on the surface of the filter and not pass through. Normal household dust that you can see floating in the air when the sun shines through your windows is visible to the human eye and able to be filtered even with the
$1.00 filters from the local hardware store, provided that dust makes it into the ductwork of your forced warm air system before it settles on the furniture or floor. This is an important point as you would be surprised how many people think that the best filter available will eliminate dusting in
their home or office. For any filter to do its' job, the air carrying the dust or pollutant must make it to the filtering device. Once at the filter the filter has to be of a certain resistance to capture the dirt yet let the air pass through. Believe it or not a soiled filter is more efficient than a clean one. This is not to say that you should operate your system with dirty filters as they can become so clogged that they will block the air flow completely and cause problems with the air conditioning or heating. The key to proper air filtration is to reach a happy median where air flow is not restricted yet proper filtration occurs. There are some excellent filters on the market that can filter out particulate down to 0.5 microns. A micron measures 1/25,400 of an inch in size. The sales literature for a filter that I personally use in my system indicates that a human hair measures 100
microns in diameter. Disposable filters are rated under a standard called "Merv", with the higher Merv number indicating the ability to remove finer particulate from the air. A good Merv rating of 8 to 13 will satisfy most customers' needs. Filters of this style are typically "pleated" (wavy, zigzag pattern that increases the square inches of surface area) The greater the surface area, the greater the efficiency. Pleated filters start with a thickness of 1" and go up to approximately 7" in thickness. The highest rated filter are referred to as "Hepa". These filters are normally so restrictive to the air flow (residential applications) that they are installed in a separate cabinet from the furnace with a separate blower fan to overcome the restriction to air flow. Even with its' own blower the Hepa filter system only filters a portion of the air in the system at any particular time. The normal filter in your furnace is still required for the balance of air that bypasses the Hepa filter. It is important to note that filters only work if the fan in your system is operating. It is obvious that constant air flow will filter more air, so you may consider operating the fan in your system 24/7. The other method of filtering air is with Electrostatic Air Cleaners. This method was popular up until the 1980's which is when I sold my last electronic air cleaner. This style of filter used a high voltage charge of approximately 10,000, volts (DC Voltage) to energize a grid assembly in the cabinet of the filter. Air and any dust passing through the first part of the grid was given a positive static charge while the plate assembly of the filter had a negative electric charge. The opposite charged particles would be attracted to the plates of the air cleaner like a magnet and stay there until washed clean. Electronic air filters were high in maintenance, requiring monthly cleaning in a laundry tub or outdoors with the garden hose. The ticking noise generated when a large particle of dust was "zapped" could be particularly annoying. Electronic air filters also produced ozone that had a noticeable odor to it. This ozone is actually smog and not the ozone that we need in the atmosphere to protect us from the suns' radiation. Another problem with electronic air cleaners is / was that their efficiency drops off as they become soiled whereas all other filters efficiency increases as they become soiled. There were many electronic air filter impersonators that came out of the quest for clean air. The 1" thick electrostatic filter appeared with the manufacturers indicating their product would do everything the full size filter would do.
They also had land in the Florida everglades for sale...
Chances are if there is something that has to be filtered from the air, there is a specific filter to do the job ranging from the residential dust filter to filters for arresting paint spray in industrial spray booths to pocketed "bag" style of filters used in large commercial air handling equipment.
Probably the most common filter for commercial / industrial roof top HVAC units is a disposable polyester media insert that fits into a reusable frame made of metal that will not collapse and suck into fan assemblies like cardboard framed filters do. There could be 1 to 20 or more of these filters in a single roof unit depending upon the capacity of the system and are normally 1" or 2" in thickness. One thing that will improve the efficiency of these filters is a spray on coating referred to as "Tack" that acts like a glue to dust. The servicemen hate them because they make their hands sticky, but appreciate that when they are pulling out the old filters that the dust does not fly off in their face. Your contractor can advise you on the cost difference for the various filters, but if you were to spend a few dollars more each year on a better grade of filter it could save hundreds of dollars in coil cleaning and efficiency loses of your system.
For residential applications, the filter that I
recommend is the "Space-gard" high efficiency air filter that will provide
you with next to hospital operating room air quality in your home. This
filter takes less than 5 minutes to replace, once every 8 to 12 months and I
can confirm personally that it can be done blindfolded in less than 10
minutes. This filter is the same physical size as the old fashioned
electronic air cleaners, but will increase in efficiency when soiled versus
the electronic filter that loses efficiency as it becomes soiled and has no
moving parts to break down. The Space-gard filter is made by the same Company that makes the "April-aire" premium humidifiers.
A method that has evolved in the last decade due to the increase in allergies, seal tight construction of new homes and the chemicals that are emitted off everything from stain guards used on furniture, carpets and household cleansers is purification of the air by "Ultraviolet Light". It took the power of observation, not brain power to recognize that mold, bacteria and viruses will not propagate in natural sunlight. Inside of your home and office the windows allow sunlight through, but not the ultra violet radiation. That is why you cannot get a suntan if you were to lay in the sundrenched privacy of your living room. When the observant ones passed on this information to the smart ones they were able to determine the types of ultra violet radiation that eliminates, mold, bacteria and viruses and as a little bonus the same UV light killed odors of just about anything you could think of. The 2 types of UV light are UV"V" and UV"C and the smart ones figured out that when this type of light was installed in a forced air system that it would eliminate pet odors, cooking odors VOCs' off most any product made, mold, bacteria viruses and even anthrax. I was somewhat skeptical of the claims and don't make a habit of promoting a product until I have tested it myself. I did test the product, both at my office and my home. I own dogs a cat, budgies and love to cook and my house is odor free. There is always odors in an office environment from perfumes, nail polish, deodorants, people that have just come in from a smoke break and there is always someone around that has a cold. This is not to say that if someone sneezes in your face that you won't get sick or if you cook bacon that you won't smell it or particularly if your dog left you a parcel on the floor, but the odors will vanish soon thereafter. I started to sell the product with great results and the inventor of the unit I was selling asked our
supplier who it was that was selling their product. When Signature Air Systems was identified the brains behind the product came from Montreal to meet me.
I learned more in half an hour than I learned in 5 years of high school. I was introduced to the large commercial unit for cleansing the air in garbage rooms of high rise condominiums. In the last year I have sold 4 of these systems and have to admit that I was somewhat apprehensive on the first when I accepted a challenge that if the unit did not perform as expected I would take it out and not charge my Customer for labor or materials. That unit is still operating in the garbage room and I have been paid in full. The old method of trying to control odors in garbage rooms was
to exhaust a ton of air and introduce fresh air. When the exhausted air bothered the owners in the area of where the smell was exhausted, engineers decided that if they refrigerated the garbage rooms they could control the odor. What they found was that they then had cold smelly garbage. The Product I have full confidence in is the "Sanuvox Air Purifier". You can see pictures of some of our installs of the product in our Gallery Section. If you would like to see all the brainiac information on the product and all the different smells and odors it will eradicate the web address is www.sanuvox.com. There are some knock off wannabees on the market, but if you read the literature on the Sanuvox your choice will be obvious.