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What is an Air Scrubber and how do you use them?

Date posted: 22 February 2017

Air scrubbers are portable filtration systems that clean the air in a room or workspace.

One of the most common uses for air scrubbers in industrial workplaces such as factories and warehouses is to get rid of toxic fumes, harmful chemicals or other unhealthy substances that are regularly being used, produced, or disposed of – and that could cause serious health issues for workers if they were left in the air. 

Some of these machines are designed to remove one specific substance, while others can deal with particles, gases, and chemicals at the same time. 

How do air scrubbers work?

Air scrubbers draw in air from the indoor environment where they are placed, and pass it through a series of filters which remove particles from the air before pushing the clean air out again. The end result is better indoor air quality.

Most units use ions or ozone to clean the air, although other types are just made up of a filter and a fan that periodically suck in large quantities of air, then force out clean air at the other side.

Most air scrubbers also offer space in the pre-filter stage for an optional carbon filter which captures the gas- and vapour-phase molecules that our human noses detect as odours. This is achieved through a process called adsorption, where the gaseous molecules are physically attracted to the carbon's surface. The addition of the carbon filter can make odorous environments far more pleasant to work in.

What's the difference between an air scrubber and a negative air machine?

Although the two terms are often used interchangeably, there is a distinct difference between these two types of machines.

Air scrubbers are stand-alone units that are placed in the middle of a room and do not have any ducting attached. The air that is filtered is recirculated once cleaned. 

A negative air machine, on the other hand, does use ducting to actually remove contaminated air from a sealed containment area to another area. This process creates a slight vacuum effect (negative air pressure) inside the containment area in comparison with surrounding areas. This helps to reduce the spread of contaminants to other areas inside the building/structure.

Many models of air scrubber can be used as a negative air machine, but this will involve some additional kit and preparation such as ductable in and ductable out; sealed housing; precise airflow adjustment; and a variable speed blower motor to maintain containment.

Should my air scrubber have a HEPA filter?

A HEPA filter offers efficient air filtration. It consists of a mat with randomly arranged fiberglass / metal fibres 0.5-2.0 micrometers thick. These filters are often found in central air conditioning units and other air purification devices such as air scrubbers. Other types of filters do exist, but the consensus is that HEPA filters are the best and most reliable.

What are the limitations of an air scrubber?

It's important to remember that while an air scrubber is powerful and very useful, there are limits to its capabilities: it helps to clean the air, but it does not help to clean surfaces. So any particles that are not airborne -- those that have settled on furniture, worktops or other surfaces, or which are drawn in to the HVAC system – are beyond the air scrubber's reach. Equally, rooms and workspaces will have areas of "dead air" that resist circulation, and therefore may not get drawn into the air scrubber. This means it is possible that an air scrubber will miss certain airborne particles as well because the contaminated air never passes through its filter system. And even the air that does pass through the filter system will have the odd particle or gas molecule remaining: even the most efficient air scrubber filter systems are only rated 99.97% effective against  particles 0.3 microns in diameter or larger. Some particles in this size range or smaller will still manage to pass through the filter system without capture.

What are the most common uses for air scrubbers?

Air scrubbers are commonly used for:

Water damage restoration: Air scrubbers are used in water damage restoration jobs because they demand a huge amount of airflow for the moisture to evaporate from carpets, furniture, drywall and other damaged materials – and this airflow disturbs a lot of debris, throwing it into the air, including common allergens (e.g. pet dander) right through to potentially hazardous contaminants that are caused by water damage (e.g. mould spores). The air scrubber will dramatically reduce the quantity of airborne particles and help to improve indoor air quality.

Dust control: Workshops, factory production lines and construction sites where large amounts of dust are generated will use an air scrubber to remove dust particles from the air, making the workspace safer and more comfortable for workers and improving productivity.

Odour control: Using an optional carbon filter installed in the pre-filter stage, air scrubbers will remove odour-generating gas molecules from the air, as well as microscopic particles – making them popular for cleaning up fire and mould contamination, remediating sewage damage, and even in standard carpet-cleaning jobs.

Fire damage restoration: In fire restoration work an air scrubber not only reduces unpleasant odours but also reduces particle counts from airborne debris stirred up during the restoration and reconstruction process.

What is the difference between “wet scrubbing” and “dry scrubbing”?

Wet scrubbing involves passing air through a moist pad, a wet cloth or a liquid chamber. As the air passes through the liquid, particles and residue adhere to the cloth, removing them from the air. The cleaned air carries on through the liquid and exits the air scrubber back into the room. Some wet scrubbing devices simply use water, while others use reagents or other solutions to target and remove specific chemical compounds. Most wet scrubbers have flue stacks or other methods of waste water disposal, and they have a reputation for being more difficult to clean.

The dry scrubbing technique, on the other hand, involves a mechanism that introduces air into the device (e.g. a fan) and a process of extracting particles and other contaminants from the air (e.g. an ionic air purifier). Dry scrubbers sometimes contain activated alumina or other porous material that is treated with selected chemicals to remove specific compounds. This technique is generally used to get rid of odorous and acidic gases from the air or from waste-water produced by wet scrubbing or other industrial processes.

Fume Extraction and Ducting


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