Suction vs Air Flow

[frkirby511]

This may be entirely elemental to many of you, but it has been something I have wondered about for some time: what is the relationship of the suction power of a machine to its degree of air flow? Could one machine have greater suction than another but not greater air flow?

 

[ahzeks]

Airflow article...

Ristenbatt Vacuum has an article (see link) on air flow that does a fairly good job of explaining airflow, suction and resistance to airlow in the vacuum cleaner system. The article includes links to other articles (see article on fan or impellor types) and a glossery of terms. So, to answer your question, yes -- when you consider the resistance to the airflow in the system. Traditional "direct air" uprights have tremendous air flow but less suction than a "clean air" canister.

http://www.ristenbatt.com/airflow.mv

 

[cirtcele]

Pretty good article...

...I want to emphasize (and possibly clarify) what they said about nozzle size, though.

Most household vacuum cleaners use a 1-1/4" diameter hose. If you can find two vacuums that have the same suction pressure at that 1-1/4" hose opening (or, just inside the hose opening) then they will both have the same airflow through their hose openings. Always.

However, once you change the size of the opening, all bets are off. A shop vacuum that could achieve the same suction pressure at the opening of a 2-1/2" hose would have dramatically higher airflow.

 

[dysonman]

Air-Flow VS suction

Suction is also knows as water lift. That's the pressure that the motor's fan (or fans) develops. Air-Flow is the amount of air moving through the machine. The filter (or bag) will restrict the airflow through the machine, as well as the clogging effect of dirt. SO, a vacuum that advertises good airflow ratings, can ONLY do so for a moment, when brand new. As soon as dirt is inhaled, the airflow begins to diminish. Airflow picks up dirt, suction (water lift) is the pressure to pull it quickly into the machine. Some vacs have great airflow with low water lift (Rainbow). Some have great pressure with low airflow.

The truth is: if the vacuum has good airflow and water lift, then it will clean well. IF the machine doesn't lose its airflow (Rainbow, Dyson, etc.) then it's an excellent machine at cleaning CONSISTENTLY. A vacuum with high airflow and water lift at first, but clogs quickly (Hoover Windtunnel 2 bagless) cannot continue to clean well for a long time and will, in fact, stop cleaning deeply very quickly. Hence the reason that Electrolux told us (in the model G's owners book) to change the bag before EACH USE.

 

[ronni]

"Hence the reason that Electrolux told us (in the model G's owners book) to change the bag before EACH USE."

Just to clarify, Electrolux Corporation didn't recommend changing the filter bag before each use. They simply stated it as an option.

I own several editions of the aqua Model G owner's manual. Except for the first edition (which includes the Turbotool) the later ones and the tan Model G's--stated in italics: "Note: If you want to put a clean bag in before the cleaner opens automatically, you may. Open the front cover by pushing down on the latch at top. Some women put a clean bag in every time they clean."

There was no such notation in either the Model R or Model L manuals. The Model R's just gave directions of how to change bags while the Model Ls' stated: "It is time to change bags either when the bag is full or when the dirt in the inside reduces the suction. Fine powdery dirt will reduce the suction sooner than loose linty dirt."

However, all illustrate and describe the benefit of Electrolux automatic self-sealing bags, including: "Now look what happens inside the Electrolux filter bag: the THREE layers of filter paper trap the dirt while air keeps on picking up more dirt. When other bags clog up, you can be sure that the Electrolux bag is still working for you." The Gs' also tout Electrolux's automatic shut-off mechanism that indicates when the bag needs to be changed according to the dial setting.

So Electrolux implied that airflow was not significantly diminished after each regular use by designing the automatic control function and in leaving bag replacement to the owner's discretion.

 

[crazykirbydude]

You need airflow to create suction. That's what suction is, movement of air. A lot of people think sealed to the floor is the way to go, such as the Eureka AirSpeed SuctionSeal or the Dyson DC40. You actually need good airflow for good cleaning power.


Just my two cents not including tax