| Terms to Know |
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| Ever get that blank look or have no idea what the person is talking about when it comes to Central Vacuums. This section was created for you. We have listed many of the terms associated with Central Vacuums and have provided a description of each and how it relates to the Air King Systems. Feel free to scroll down and read all the terms or click on the specific term below for more information. |
| Suction (also called Vacuum or Waterlift) |
| Airflow or CFM (Cubic Feet Per Minute) |
| Airflow Velocity |
| Air Watts |
| Decibel Ratings |
| Effective Orifice (Working Vacuum) |
| Amps |
| Micron or Micrometer |
| Dual Motor - Air Series/Air Parallel |
| Motor Stages |
| Motor Armature |
| Motor Field |
| Flow Through Motor |
| Peripheral By-Pass Motor |
| Tangential By-Pass Motor |
| Filtration |
| HEPA |
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Suction (also called Vacuum or Waterlift)
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| This measures the suction strength of a central vacuum motor. Essentially, it tells how much "pull" or "lift" power the motor has. This measurement is always taken at it's maximum value at the 0" inch orifice (sealed vacuum) where suction is at it's greatest. |
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| Often referred to as Inches of Waterlift or Vacuum, Suction is vital to overall system performance since it is the "pull power" that creates the velocity of Airflow necessary to move debris through the complex network of vacuum pipe, hose and accessories. While Airflow is necessary for a vacuum cleaner to work, suction creates the lift and the airflow velocity which sweeps the dirt away. |
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| Of any performance rating, suction is perhaps the best measurement to evaluate since it remains the most constant in a typical home installation and plays a crucial role in providing and maintaining performance where it counts, at the end of your central vacuum hose. |
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| Understanding Suction |
| Suction (Vacuum) alone does not move dirt and debris but it is crucial for system performance. |
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| Consider this: Place a marble on a table, then with the unit shut off, place your hose nozzle over the marble so that no air can enter. Next, turn the unit on, wait a few seconds then shut the unit off then lift the nozzle off the table. You will notice the marble hasn't moved even under tremendous vacuum! Now perform that same experiment but when the central vacuum is running, lift the nozzle off the table so that air can enter. You will notice the marble whisked away due to the rush of airflow. If not for suction power, the velocity of airflow needed to sweep that marble away through the complex network of a typical central vacuum system would be insufficient. |
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| Airflow or CFM (Cubic Feet Per Minute) |
| This measurement takes into account the volume of air being displaced in a vacuum system. Airflow is usually expressed in cubic feet per minute or CFM. The more Airflow/CFM a unit has the more air movement is generated thus increasing sweeping power. This works in tandem with Suction in your central vacuum system. |
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| Airflow can be a bit confusing however. Since all performance measurements are taken directly at the motor in a laboratory setting, this does not factor the resistance found in a typical central vacuum system. Filtration, piping, hose and accessories used all restrict and reduce the amount of actual Airflow a system has. While Airflow is important for cleaning and moving dirt, Suction or the “pulling of air” maintains the Airflow velocity necessary to sweep dirt and debris away. |
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| Understanding Airflow |
| Airflow (CFM) is the movement of air which sweeps dirt away like dust in the wind. However without suction the movement of air is non-existent so it is necessary that both CFM and Suction work together. While it is this movement of air which carries debris to its final destination in your central vacuum, restrictions within your system cause friction which in turn reduce Airflow. |
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| Consider this: Take a dish towel folded in two and cover your mouth and blow through it. Now do the same without and blow. You will notice the amount of airflow is far greater without the towel over your mouth. The same thing happens in your central vacuum installation which is restricted by the friction loss through the piping, filtration, hose and tools. |
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| Airflow Velocity |
| Velocity: This factor is an expression of the speed at which air is moving at any given point in the vacuum system, expressed in feet per minute (FPM). While Airflow (CFM) will tell us the amount of air moving, a Velocity measurement tells us how fast. There is a linear relationship between airflow and velocity. As one goes up, the other goes up directly. If you know the airflow CFM and the size of the opening it is passing through, you can then compute the velocity as follows: Formula: Velocity (FPM) = Air Flow (CFM) divided by tube area (sq. ft.). |
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| Understanding Airflow Velocity |
| While this is a term you will never see published in any central vacuum brochure or specification sheet, it is worth mentioning as a means of understanding how airflow works to clean your home in tandem with Suction (waterlift). |
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| What’s the difference between the wind picking up dust and blowing it around compared to a full blown tornado? Intensity yes, but moreover it is the velocity of air or if you like, the velocity of airflow. The speed at which air travels (i.e. velocity) has a direct impact on its ability to move debris. In the case of a gentle ocean breeze versus a tornado/hurricane…this is the difference between drying your laundry and ripping your house off its foundation! |
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| A household fan and a bathroom exhaust fan can produce a lot of airflow comparable to the output of a central vacuum, but neither are capable of generating enough Suction (waterlift) to overcome those resistance's found in a typical central vacuum system hence the velocity Airflow (CFM) needed to sweep dirt away depends on the power of suction. |
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| Whether you realize it or not air has weight and as ever so slight as it may be, it must be pulled through the maze of central vacuum piping and ultimately through your central vacuum system. This is where suction comes into play. The more suction the greater the ability to “Pull” air through any given situation. This is why Suction (measured in waterlift) is so important. Without Airflow (CFM) dirt does not move, but without Suction there is no Airflow. The stronger the amount of Suction the greater the velocity of air trying to fill the vacuum that is being created inside your system. |
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| Air Watts (Suction x Airflow divided by 8.5) |
| There is a way to quantify and predict where the "sweet spot" of a vacuum performance curve lies. The computation of air watts takes into account the effects of both Airflow and Suction values at the same orifice size. HOWEVER... this is perhaps the most widely used and misunderstood term used in the vacuum industry. |
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| Yes, it is true that Airwatts represent a measurement of overall vacuum performance (at the motor), the fault is that this performance measurement is always taken directly at the motor and not at the end of the hose where actual vacuuming takes place. BIG difference. While sealed suction remains relatively consistent and can be measured on a suction gauge, the impact on Airflow in a central vacuum system after passing through all the piping, hose and filtration is huge. Therefore in the Airwatts calculation using Suction x Airflow divided by 8.5, the Airwatts measurement advertised in the sales brochure is far from accurate. Therefore it is important to caution that Airwatts do not indicate the true cleaning performance of the complete central vacuum system (unless calculated at the end of the vacuum hose unique to your home installation.) |
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| Understanding Airflow Velocity |
| Consider This: Imagine breathing in as fast as you can. The strength of your lungs expands quickly to create (Suction) and oxygen rushes quickly into your lungs creating (Airflow). The Suction power of your lungs x Airflow divided by 8.5 would equal Airwatts. Ok, now using the example of the dish cloth we used for Airflow. Imagine now that you are trying to breathe in quickly through a dish towel folded in two versus breathing in without a towel covering your mouth. Your lungs are still just as strong and are capable of producing the same amount of suction with or without the towel, however the airflow or the rate at which you can breathe air in is restricted by the towel. The same is true in your central vacuum, only the central vacuum motor is like the lungs of your central system breathing in through 30' of hose, piping, fittings and filtration. Hence we can say that Airwatts is not an accurate performance measurement unless taken at the end of the vacuum hose. |
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| Decibel Ratings |
| While decibels are a measurement of sound volume, the average human ear cannot perceive a significant difference in volume between 5 decibels. Manufacturers who offer quiet units will generally provide a decibel rating for their units promoting how quiet their units are. In principle, there isn't any problem with this except that there isn't an industry standard by which these claims are substantiated or governed. In other words, any manufacturer could change their decibel rating by taking a measurement further away from the unit, by venting the unit outdoors, or even changing the size or acoustics of the room. There isn’t any standard. |
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| REALITY CHECK: There are a tremendous number of variables which can be used to create the desired sound decibel rating, hence you see a number of manufacturers all claiming to have the quietest unit! In reality, the central vacuum unit is generally installed in the garage, utility closet or basement which means the sound you hear would be minimal at best and if your unit is designed for quiet operation, so much the better. The area which you should be more concerned with is at the end of the hose where you vacuum. It is the accessories you use when you vacuum so choosing a quieter powerhead naturally means quieter operation in the room you are vacuuming. If you are not using an electric powerhead, the only sound you should hear is the rush of air entering the hose nozzle and maybe the distant whirr of the central unit. |
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| Effective Orifice (Working Vacuum) |
| This is the orifice size where your typical vacuuming takes place on a daily basis with the accessories etc. Ametek/Lamb (prominent manufacturer of central vacuum motors) suggests that the true effective or working orifice of central vacuums is at the 5/8" inches orifice (.625" inches) and ranges to up to to 3/4" inches (.75" inches). This is a measurement you will rarely if ever see promoted, but it is the orifice size that all performance measurements should be taken. |
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| Amps? |
| A measure of current that a motor draws and does not measure cleaning performance. Amps is more of a marketing ploy for portable and canister vacuums to indicate perceived power. It does not actually measure cleaning ability. |
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| Micron or Micrometer |
| Defined as 0.001mm or 0.0003937 inches. 20.0 microns is the smallest size visible by the average human eye. Examples of micron sizes: Pollen 10.0 to 50.0; household dust .01 to 20+. When evaluating filtration in central vacuums look for the micron rating as well as the efficiency rating, the lower the micron value the better. The efficiency rating indicates how much of the particles at the given micron size are captured. For example, the HEPA membrane filter of the unit will filter down to 0.3 micron at 99.97% efficiency*. This efficiency means that .03% of particles at .3 micron (the size of some viruses) will pass through the filter. - IBR - Test Results - ASTM F1977-99 |
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| Dual Motor Systems |
| Air Series |
| One vacuum motor feeding it's heated dirty discharge air into the intake of the second motor. Increases vacuum suction (inches of waterlift) by 160 -170%. This design is not recommended as higher air temperatures in the fan system could result in bearing problems due to the elevated temperature. THIS METHOD IS NOT RECOMMENDED BY THE MOTOR MANUFACTURER |
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| Air Parallel |
| While operating vacuum motors in air parallel, two motors draw air from a single plenum chamber. This has the effect of nearly doubling the airflow (CFM) of the system while the vacuum (inches of waterlift) level remains comparable to a single motor system. "When applying motors in this manner, care must be taken in the design to accommodate the increased airflow. If restrictive tools and hoses are used in a cleaner, the potential air flow advantages gained by the parallel arrangement may be negated." Ametek/Lamb Product Review. |
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| Motor Stages |
| Indicates the level of fan assemblies in the motor. A (3)-stage motor for example has three fan levels to create vacuum whereas a (2)-Stage only has two. It is the fan assembly which creates the suction necessary to create vacuum and airflow. |
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| Motor Armature |
| This refers to the copper wound rod which runs through the center of the motor on to which the fan assemblies are attached. |
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| Motor Field |
| Creates a magnetic force which propels the armature and thus turns the fan assemblies. |
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| Flow Through Motor |
| Inexpensive, these motors are generally used in conventional canister vacuums or upright vacuum cleaners with the larger more powerful versions used in a central vacuum. Aside from being less expensive they also make a central vacuum sound quieter since there isn't a cooling fan spinning at speeds in excess of 20,000 RPM. This motor uses vacuumed air to cool itself by passing vacuumed air over the armature. It is critical then that care be taken to insure air is filtered and clean to prolong the life of this motor. Often you will see this type of motor in less expensive systems or you may find them used in a dual motor situation whereby two lesser powered motors are used together to create a more power system. We will talk about that later. |
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| Peripheral By-Pass Motor |
| Again typically less expensive then a tangential type motor, these motors actually employ a cooling fan on top of the motor which blows fresh clean air over the armature and exhausts it peripherally through vents on the side of the motor. Generally more powerful then their Flow-thru cousins these motors should be more reliable since clean fresh air is being use to cool the armature. Care should be considered in the exhaust of this unit which is dirty and heated. |
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| Tangential By-Pass Motor |
| This style is the most commonly used motor in the central vacuum industry. While more expensive then it's cousins, the implementation of a tangential exhaust ensures all heated and dirty exhaust is removed from the motor chamber and expelled thus maximizing longevity. Available sizes are usually 5.7" Diameter and 7.2" Diameter; the latter generally producing more power at the same or lower RPM. |
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| Filtration |
| The true benefit of any central vacuum is that 100% of vacuumed contaminants are removed from your living area and safely exhausted when vented outdoors which is why central vacuums have been clinically proven to improve indoor air quality and reduce allergy symptoms. The filter in your central vacuum serves two purposes (1) First and foremost to protect the central vacuum motor from fine dust particles and (2) If the filter is efficient enough it allows the unit to be safely vented indoors. Virtually all manufacturers use a filter of some description in their unit with the exception of a true cyclonic system which attempts to remove as much debris from the air stream as possible and the rest exhausting through the motor which is not a good thing. |
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| Conclusion: Essentially what you are looking for in filtration is something that provides adequate protection for the motor but does not require any effort on your part to have to maintain it. First of all remembering and secondly having to reach up inside a dirty stinky central vac unit to have to remove a filter is not a fun job. Choosing a filter that does not require mandatory maintenance takes the guess work and hassle out of the equation. |
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| HEPA |
| HEPA is an acronym of High Efficient Particle Arrestor. Any true HEPA filter guarantees that the filter will capture airborne particles down to 0.3 microns in size, 99.97% of the time. (Particles smaller than 0.3 microns are still trapped by HEPA filters but effectiveness is reduced to less than 99.97%.). The problem is that today HEPA is thrown around so often that it has become watered down. You will now see manufacturers promoting "HEPA like" or "HEPA type" filtration just so they can use the word "HEPA". |
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| Consider This: The better the filtration on your central vacuum system the more protection it offers the motor and secondly, if you are exhausting your central unit indoors, a more efficient filter will filter out more potentially harmful contaminants. If you plan on exhausting your unit indoors, it is best to choose a central vacuum system with the best filtration to maximize the purity of your indoor air. |
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