Air Scrubber versus Air Purifier Explained
Air scrubber is a relatively new term that describes an industrial air purification system that removes gases or particles from the air. It is commonly used to clean industrial exhaust streams and gas emissions (gas scrubber). An example would be the removal of sulfur from a power plant exhaust system.
History Of Air Scrubbers
The term 'scrubber' comes from the use of a liquid to wash pollutants from the air. In other words, the air is scrubbed of the unwanted pollutant. A wet scrubber refers to this type of air cleaning where a liquid is sprayed to clean the air. Wet scrubbers often use water as the scrubbing liquid. The other type of air scrubber is the dry scrubber, which uses a fabric or mechanical filter to clean the air. For example, a HEPA or carbon filter.
In most cases, an air scrubber is used to remove gases. The first use of an air scrubber was to remove carbon dioxide from the air and this same type of system is a key air filtration system used in submarines.
Differences Between Air Scrubbers & Air Purifiers
In contrast to an air scrubber, an air purifier typically refers to a type of air cleaning that is filter based. The most common type is the HEPA filter air purifier. Other types include electrostatic plates that use electrical charges to attract particles to metal plates in the air purifier. There are also some ozone generators that are meant for cigarette smoke removal in a commercial space.
A commercial air purifier is used in commercial and industrial applications for the removal of particulates or gases. An example is a clean room that requires the highest level of air filtration. Industrial air purifiers are also used in manufacturing, office buildings, museums and hotels. Some of the jobs include mold abatement, restoration jobs, creating negative pressure, oil mist eliminators, flue gas removal and maintaining the indoor environment within tight tolerances to protect art work.
Commercial air purifiers with large amounts of activated carbon or other gas phase media are used to adsorb gases like cigarette smoke. They can also serve functions as fume scrubbers for vapors from printing or nail salons, containment units, and many other applications.
Where there becomes an overlap is in the area of light commercial air purifiers. Some of these products are also referred to as portable air scrubbers. In this case an air scrubber is more like a room air cleaner and meant to clean the indoor air in a larger space. If they are used to remove smoke they are sometimes called smoke eaters. A smoke eater may use a technology like ozone to zap a room of any unwanted odor.
These commercial air scrubbing systems are more expensive than a typical home air purifier. They are also built more durably as they are designed for industrial use. In some cases an air scrubber can be rented to perform a specific job like mold remediation. In this case, the air scrubbers tend to be small with inexpensive filters to be affordable.
HEPA Air Scrubbers
If you need to remove fine airborne particles such as mold spores, dust, pollen, or particles in tobacco smoke then the air scrubber will need true HEPA filters or better. Please note that while HEPA filters are best at removing particulate matter they do not remove odors. This means they can remove cigarette smoke particles but not the related gases and smells.
Air filters are rated based on the MERV ratings scale. A true HEPA filter is MERV 17 (like our EJ air purifier). A better than HEPA rating, approaching ULPA level is MERV 18 like our Erik650A.
The challenge with a HEPA air scrubber is getting enough air flow through the bank of filters since high efficiency filters have more air flow resistance. This resistance is also called pressure drop. To move enough air requires either a dedicated fan such as in a portable air purifier. Or a booster fan in the HVAC system. This is because HVAC or forced-air heating systems are not designed to move the air through a dense group of air filters. They are often designed to only remove the large particulate matter for the sake of protecting the HVAC system. They are often not designed for indoor air pollution control.
In office buildings a HEPA air scrubber is sometimes used along with germicidal UV light to prevent mold growth. UV-C light can act as an air sanitizer to prevent standing water in air ducts from turning into mold. This is important in maintaining good indoor air quality. There are also concerns around Legionnaire's disease in large buildings. Legionnaire's disease is a form of pneumonia that is caused by bacteria.
What is a Negative Air Machine?
A negative air machine creates negative pressure in a room so air can flow into an isolated room and keep it there. The purpose is to keep contaminated air from escaping a given room. This leverages the principle where air naturally flows from areas with high to low pressure areas.
Smoke and Odor Removal
There are a few ways an air scrubber can remove smoke and odors from a space.
- One is through the use of ventilation if connected to your building's HVAC system. Bringing in fresh air from the outside is a great way to improve the indoor air quality.
- A second way is to use a negative air machine. A negative pressure system works by removing the air pollution through ducting often to the outside. This creates a negative pressure in the space that is being treated so the air contaminants are contained to one area and hopefully ventilated away.
- Carbon air scrubbers remove smoke and odors through the use of materials that adsorb these gases. This includes granular activated carbon, alumina and potassium permanganate. This is what we use in our EJ and Erik650A air cleaners. They provide clean air in larger square footage spaces than you typically find in a room air purifier.
- An alternate method is to use an ozone generator. These devices are used exclusively for commercial use since ozone is a serious lung irritant. Ozone is not meant to be used when people or pets are around due to the damaging effects to our lungs. It can be very effective for smoke removal or in removing a smell that otherwise cannot be removed.