Saturday, October 16, 2010

Vacuum Cleaner Filtration

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Filtration is a mechanical or physical operation which is used for the separation of solids from gases (Air) by interposing a medium (Filter) through which only the air can pass. Oversize solid particles in the air are retained in the filter media, (depending on the pore size and filter thickness).
Filtration DiagramDiagram of simple filtration: oversize particles in the FEED (Dirty Air) cannot pass through the lattice structure of the filter, while air and small particles pass through, becoming FILTRATE.
If you can imagine in time, the more oversized particles that get stuck in the filter the harder it is for air to pass through and even the smaller particles will get caught up in the filter giving you less volume of FILTRATE but cleaner air with less particles. 
Note:  If it requires 10 lbs of pressure per square inch to keep the FEED flowing through the filter when it is clean, it will take more pressure to maintain that same flow amount after the filter has begun collecting the large particles and clogging up the pores of the filter.  How much more pressure will depend on the amount of oversize particles retained by the filter.
Looking back to the diagram, if the darker yellow area around the outside of the filter does not make a good seal with the filter and air is allowed to bypass around the filter, the filtration efficiency is compromised and the quality of FILTRATE is lowered sometimes the same as the FEED.  This effect takes place more as the filter becomes clogged with particles creating greater resistance.
HEPA FilterThis filter to be labeled in the USA as a HEPA filter, must meet HEPA Filtration Standards of filtration.  This standard is 99.97% efficient to .3 microns.  This in simple terms means it must remove 99.97% of all particles the size of .3 microns or smaller.
Today, a HEPA filter rating is applicable to any highly efficient air filter that can attain the same filter efficiency performance standards as a minimum and is equivalent to the more recent NIOSH N100 rating for respirator filters. The United States Department of Energy (DOE) has specific requirements for HEPA filters in DOE regulated applications. Products that claim to be "HEPA-type", "HEPA-like", or "99% HEPA" do not satisfy these requirements and may not have been tested in independent laboratories.

    Applied to Vacuum Cleaners

Bagged Vacuums

A bagged vacuum cleaner whether an upright or canister, is a vacuum cleaner that the primary filtration is a paper, cloth or synthetic bag located either on the inside or outside of the vacuum cleaner.  This bag acts as the first level of filtration catching large particles and allowing the cleaner air with only smaller particles to pass through the pores of the bag.
In the past ten years most vacuum manufacturers improved their filtration and added an additional (secondary or final) filter to the bagged type vacuum cleaners.  This filter is many times called a HEPA (High Efficiency Particle Arrest) filter.
For a HEPA filter in a vacuum cleaner to be effective, the vacuum cleaner must be designed so that all the air drawn into the machine is expelled through the filter, with none of the air or particles leaking past or around it. This is often referred to as "Sealed HEPA" or sometimes the vaguer "True HEPA".  Vacuum cleaners simply labeled HEPA have a HEPA filter, but not all air necessarily passes through it. Finally, vacuum cleaner filters marketed as "HEPA-like" will typically use a filter of a similar construction to HEPA, but without the filtering efficiency causing poor airflow or less than desirable filtration.  Because of the extra density of a HEPA filter, HEPA vacuum cleaners require motors with higher airflow and suction combined to provide adequate cleaning power.

Bagless Vacuums

Bagless type vacuum cleaners whether they are canisters or upright vacuum cleaners, usually have a HEPA or HEPA type filter attached to their exhaust also.  Unlike the bagged type vacuums, bagless machines do not always have a primary filter as their first defense of capturing the large particles in the air that is being sucked into the vacuum.  Some are designed with pre-filters made of washable foam and most also use centrifugal force to attempt to separate the particles from the air and then finally force the air through a HEPA or HEPA type filter to expel only cleaned air.
Cyclonic Assembly DiagramSince most readers are familiar with the Dyson brand of vacuum cleaners we will use one of their cyclonic units as an example of how bagless vacuums work.  Keep in mind all bagless vacuum cleaners do work similarly the same.  Dyson uses the term cyclone technology, but it is still simply centrifugal force that separates the large particles of debris from the air.
This type of filtration is the equivalent to a low quality filter or vacuum dust bag.  Many (Not All) manufacturers also include a motor filter after the cyclonic assembly to catch somewhat finer particles prior to the air passing through the motor.  Once the air has been cleaned of the large particles it still needs to pass through a HEPA filter to finish cleaning the air before it is expelled from the vacuum.  All of these filters and even the centrifugal forces use energy and restrict airflow lowering your vacuum cleaner's efficiency.
Note about all information above:  Vacuum cleaners in and of themselves, do not loose suction, That is a myth.  Dirt clogging passageways and dirty filters are the cause of loss of suction.  The suction from the motor is relatively the same in a new motor or a 10 year old one.  Electric motors do not get “Tired” like gas powered engines.

What does all this mean to you?

When choosing a vacuum cleaner, filtration type and quality is an important part of the process.  We find that allergy sufferers tend to pay closer attention to the filtration quality of the vacuum and less attention to the overall design and efficiency of the unit.  If design and efficiency is over looked allergy sufferers might find themselves purchasing a vacuum that has a great filter but does not have the sealed aspect of the HEPA filter or a machine that does not have enough power to push the air through the filter thus lowering the overall cleaning effectiveness.  
In addition, many people purchase a less expensive vacuum based on what the outer box claims being tricked by the simple term “HEPA” rather than doing research to be sure that vacuum is properly designed by a creditable company with the correct balance of filtration efficiency, cleaning effectiveness and ease of use.
Since the introduction of HEPA filters to the vacuum cleaner industry, most manufacturers have been forced to boost the power consumption of the motor in the vacuums to the maximum allowed by UL (United Laboratories) for household appliances just to accommodate the back pressure or resistance caused by HEPA filters.  This has caused a great increase of energy consumption in mainstream box store vacuum cleaners and in doing so has caused more noise, shorter average life spans, and more heat generated by these electricity-hogging vacuums.


Vacuum cleaners are a major appliance in your home.  They offer great results when they are designed and manufactured correctly.  They do require the same amount of thought to purchase as does any other major appliance in your home.  Don’t sell them short and please do your homework, finally; by all means ask questions when making a purchase.

Health Risks

Boy with inhalerThe Environmental Protection Agency (EPA) has linked fine particle exposure to adverse health effects, including premature death, aggravated asthma and chronic bronchitis.1 While individual particles are invisible to the naked eye, collectively they can appear as smog or dust clouds.

Particles measuring 0.3-0.5 microns in size have a greater likelihood of being deeply inhaled into your lungs, where they can be absorbed into the bloodstream or remain embedded in your lung tissue for extended periods of time.

Those at the greatest risk are the elderly and children, along with those with pre-existing respiratory or cardiovascular disease. Even the healthy, may experience dangerous symptoms from elevated exposure to particle pollution including:

  • - Irritation of the airways, coughing or difficulty breathing
  • - Decreased lung function
  • - Irregular heartbeat
  • - Heart attacks
1Health and Environmental Effects of Particulate Matter
U.S. Environmental Protection Agency

Hidden Offenders

Woman with AllergiesTo combat the severity of this health epidemic and the gravity of its impact, the federal government has passed the Clean Air Act requiring the EPA to set National Ambient Air Quality Standards (NAAQS) for the six air pollutants deemed most harmful to public health and the environment.2 Particulate matter (PM) constitutes one of these six most dangerous pollutants.

Fine particles originate from a variety of sources. Outdoors, they're generated by the 'usual suspects'... diesel trucks, fuel combustion and power plants.

What might be surprising to learn is that fine particles are polluting your indoor air quality as well - contaminating the very air your family breathes in the confines of your seemingly safeguarded home. These invisible culprits have many sources including wood stoves, air fresheners and most vacuum cleaners.

As a result of normal motor wear and tear, vacuum cleaners can actually pollute the air you breathe - exhausting millions of fine particles per minute. And, unfortunately, legislation has yet to be put in place to regulate these indoor polluters.

2 Particulate Matter, American Lung Association.

Carbon Emissions

Carbon emmisions ChartInterbasic Resources (IBR), an accredited third party laboratory undertaking the testing of particulate contamination and filtration performance verification, was commissioned by Miele to conduct an efficiency test of five leading vacuum cleaner brands to assess their respective emissions' rates.

One test was conducted to determine the volume of carbon dust particles emitted from each vacuum cleaner's fan. The ensuing test results were alarming with the poorest performing unit discharging over 13 million particles (0.3-0.5 micron in size) per minute. These sized emissions constitute the very particulate matter that the EPA warns, and regulates, against.

Miele captured motor emissions most effectively, emitting 638 times fewer carbon dust particles than the average vacuum cleaner tested.

Filtration Efficiency

Filtration ChartIBR tests were conducted to measure complete emissions efficiency – evaluating each unit's overall capture and retention rate. At Miele, we believe it is essential that dirt, dust, allergens, pet dander and other lung damaging particles are not only confined while vacuuming, but retained. The test findings reveal that Miele captures significantly more fine particles, with the nearest brand releasing 21 times more particles per minute.

On average, a homeowner will vacuum three times a week for approximately twenty minutes per session. Resulting IBR data showed that the leading bagless vacuum cleaner has an emission rate of 175,928 fine particles (0.3-0.5 micron in size) per minute. Therefore, vacuuming with this model for one 'session' will emit over 3.5 million particles, leaving one to conclude that one week's worth of vacuuming will subject you to over 10.6 million particles.

Note: Requires free Adobe PDF Reader

Safeguarded Air

 Happy familySafeguard the air you breathe
You take every measure to provide superior care for your home and most importantly for your family – selecting pesticide-free produce, locating eco-friendly cleaners and using toxic-free detergents. But the very task you perform to clean your home, vacuuming, may not only be ineffective, but a cause of indoor air pollution.

Not all vacuum cleaners are created equal. In fact, IBR tests have proven Miele to be 99.99+% effective in both capturing and retaining particles 0.3 micron in size (that is 1/200th the width of a human hair) and larger.

Original Sealed System

Improperly sealed vacuum cleaners allow air, and particular matter, to escape from non-filtered openings. Miele vacuum cleaners offer a true Sealed System, each individual compartment and the system as a whole are sealed with one continuous, durable rubber gasket.Air-Clean SystemOriginal
Miele's exclusive Sealed System design combines with the following three elements to ensure your indoor air quality:
  • Use of the very best raw materials available.
  • Unique, electrostatically charged filtering dustbag and an innovative spring-loaded collar that traps debris
  • A selection of high-quality filter cartridges, including a certified HEPA filter.

Buyer Beware


Consumer AlertImitation turns from flattering to dangerous when imposter vacuum parts are put to use. Miele's Sealed SystemTM design is the most effective and hygienic method of removing particulate matter from your home... but only when genuine Miele dustbags and filters are used.

Tests conducted by IBR show that a counterfeit dustbag and filter does not effectively capture particles - increasing your exposure to harmful substances.

Not only will counterfeit parts increase your exposure to fine particles; IBR test results show that they reduce your vacuum's air flow. Undermining cleaning performance by more than 12%.


  1. Nice info here. Keep us these great posts!

  2. Very nice info about "Vacuum Cleaner Filtration". Its very use full for us

  3. Very nice info about "Vacuum Cleaner Filtration". Its very use full for us

  4. Camelia Brown: Incredible information I've never knew. Thanks for writing a totally awesome content about vacuum cleaner.