Aeroplane Cabin Air Filtration

How clean is the air in an aeroplane?

It’s a surprise to find that the air you breathe on a plane is a thousand times cleaner than the air you breathe in stores, bars, restaurants, or cinemas. The air you breathe inside an aircraft is not as pure as natural air, but it is better and safer to an extent. It’s time to break the myth that if one person is sick on an aircraft, all other passengers will get sick as they are all breathing the same air.

Having access to clean air has become a concern globally with the widespread of the COVID 19 virus. It has made hand sanitizers, face masks, and Personal Protective Equipment (PPE) a part of daily routine. In such a situation where people are more concerned about air quality, airplane cabins are a major focal point among the potential hotspots for infections. But the air inside an airplane is cleaner than you might think. Here’s why you don’t need to panic about the air up there

Why do you need cabin air filters?

As well as the passengers in the aircraft cabin, high concentrations of dust, fibers, bacteria, and other microorganisms may also be present inside the aircraft cabin. All of these contaminants have the potential to bring health hazards to crews and passengers. Hence air filters such as HEPA filters are widely used in order to enhance passenger and crew health and comfort.

How clean is the air on planes?

In most of the modern commercial aircraft, the air inside the cabin is supplied by an Environmental Control System (ECS) which is designed to harness the cabin temperature, cabin pressure, maintain the quality of air, and filter out any smoke, and Particulate Matter (PM) that is present in the air.

Two types of contaminants need to be controlled within the ECS,

  • Particulate contamination- Particulate matter such as dust, bacteria, and viruses’ range in size from 1000 µm down to 0.01 µm.
  • Gaseous/vapor contamination – Gases such as Carbon dioxide, Ozone Vapors such as water vapor, Organic vapor, odor.

The majority of modern commercial aircraft use a reticulation-type cabin air system. It blends fresh air up to 50% recycled cabin air followed by HEPA (high-efficiency particulate air) filters that can capture at least 99.97% of airborne microbes by circulating the cabin air once in every 2 to 4 minutes.

What is a HEPA filter?

HEPA filters can be any filter element with 85%-99.995% removal efficiency as recorded in European air filter efficiency classifications. True High-efficiency HEPA filters, which similar to HEPA filters found in hospital operating theatres are used in aircraft along with cabin air reticulation systems. Three main filtration mechanisms are used in HEPA filters to remove airborne particulate contamination with 99.99% flame test efficiency or equivalent 99.97% DOP (di-octyl phthalate) efficiency.

Direct interception

Filters contain matrices of defined pores. If the particles (10 µm in size), are larger than the pore sizes then they fail to go through the medium and this process of removing particles from the stream of air is called Direct Interception.

Inertial Impaction

The process of removing particles smaller than the filter pore size is called the inertial impaction. Generally, particles that come along with the stream of air have a higher density than the air. Hence particles deviate from the airflow stream-line due to inertia. The deviated particles impact on the solid surfaces or walls of the pores formed by the fibers of the filter medium where they adhere and get captured. This mechanism is effective for particles in the from 0.5 to 10 µm range and this is the dominant removal mechanism.

Diffusional interception

Baby particles (less than 0.1 µm in size), subject to Brownian motion with rapid random movements about a nominal trajectory. This causes the particles to come into contact and get collected on the pore walls and fibers of the filter medium. Particle removal efficiency in this mechanism increases with higher Brownian motion.

A HEPA filter becomes more efficient when it becomes dirtier. Hence it can handle heavy passenger load. This has a quick air circulation process where it can make complete air change around 15 to 30 times per hour or once in every two to four minutes.

Carbon adsorbent for VOC/odor removal

Adsorption devices are used along with HEPA filters in order to eliminate the gaseous or vapor contaminants from the aircraft cabin air. Adsorbents (Activated carbon and activated clay is used in most applications) used in these filters are chosen according to the gaseous or vapor contaminants that need to be removed. These adsorption filters are suitable for low-temperature applications and eliminate a variety of gaseous/vapor contaminants from the cabin air with high efficiency. Another advantage is no electrical power is needed. Yet the filter efficiency decreases with time when contaminants accumulate on the adsorbent and need to replace the filter media.

Carbon adsorbents are used in.

  • Airbus A320 family
  • Airbus A330 family
  • Air busA340 family
  • BAe146 aircraft
  • Boeing 737 aircraft
  • RJ family of aircraft

FLTR Commercial Aircraft Filtration Products

At FLTR we supply a range of equipment to filter and condition air for various aircraft families to keep your crew and passengers safe. Our products cover all your filtration needs.

To see our full range of Aerospace and Aeroplane filters simply head over to: https://fltr.com.au/product-category/aerospace/

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