Direct air motor vs Clean air motors

[marcusprit]

Suction and airflow are linked together. Without suction theres no airflow.

 

[kirbysthebest]

Without suction theres no airflow

You can have dead suction, such as picking up the bowling ball trick, and still have no airflow; which would not move anything because the suction is dead.

You can also have airflow, like a dryer, where it moves 180 CFM, but it is mass air flow very little suction because the air is being replaced as quickly as it is being removed. The air flow carries out the damp warm air in a dryer, as is the air flow that moves the dirt off the carpet and into the capture system.

In a suction cleaner the previously mentioned bell shaped nozzle multiplies the airflow where there is more air being exhausted than is entering this creates the suction that works together with the airflow to do the cleaning.

Though I am not a physicist there was someone that posted the formula one time where as air flow increases the suction decreases, and vis versa.

This is where the principle of the tandem air machines come in where as one motor is creating the airflow close to the carpet the clean air motor is removing the back pressure and supplying the hose suction when needed. They work together in tandem.

 

[hoover78]

Matter of prefrrenve

Omg you guys are just soooo anal about all this. No one has a friggin beach of sand in there carpets. Direct air or bypass clean air is a matter of preference IMO. U find what suits your needs. I myself have a plain ol kenmore progressive upright vacuum and I find it cleans well for me. I like the conviniece of the on board tools and hose. The agitation is good. I get to use hepa bags so it maintains that strong suction and airflow as the bag fills. Manual height adjustments are another plus. So I feel all this debating and vids back and forth is nonsense. U find what works for u and stick with it. Everyone will have their own opinion of a "good cleaner".. No one will ever be 100% satisfied.

 

[marcusprit]

But it is the fan on the motor that causes a drop in ambient pressure which produces suction which produces airflow. Suction and airflow are linked

I'm no physicist either haha

 

[kirbysthebest]

I can not speak for to others

But I was not trying to sell anything or change anyone's preference. We were having a discussion about the different types of machines. There was science, and math and other stuff like that involved.

You are correct, use what you like and it will be the best.

 

[kirbysthebest]

Yes suction and air flow are linked, but as one increases the other decreases. A dead air flow, strong suction. High air flow, low suction. Linked. Optimized.

 

[marcusprit]

Andy I was just interested in the difference between a direct air and a clean air machines performance. I don't believe in anal myself.

 

[sebo_fan]

Are you sure?

 

[marcusprit]

Positive! Though I might be in a minority on here. Haha

 

[hoover78]

Anal is fun

haha..

 

[marcusprit]

As far as I'm concerned it's an exhaust pipe.

 

[kirbysthebest]

Drifting, Drifting

Thread is drifting.

Back to air flow.

And BTW, you can have a beach of sand in your carpet. A carpet can hold ond and one half times it's own weight in dirt and still look clean to the naked eye.

 

[sptyks]

Suction vs Airflow

Harley is absolutely correct when he explains the concept of Suction vs Airflow!


 


Here's another way to look at it: A Tornado is a whirl of wind. There is almost no suction involved, but a Tornado can pickup a house and carry it 100 yards with very little or no


suction.


 


Take a look at your average Dyson. There's lots of suction as measured in inches of water, but take out your Baird Meter and measure the Airflow and you'll find there's very little.


 


Now look at your Kirby or metal Royal and you'll see these numbers are reversed. There's very little suction, but the Baird meter is nearly pegged at "10". Now as the brushroll, spinning at 3900 RPM, brings the dirt to the surface of the carpet, all that Airflow picks up the dirt (just like a tornado) and carries it through the fancase and into the bag. And that's why Airflow is more important than suction.


 

 

[marcusprit]

So where does the airflow come from Stan? It comes from the fan creating low pressure which produces suction without suction there will be no airflow! So they are both tied together one is not more important than the other.

 

[sptyks]

Marcus, I want you to understand this concept, so please read slowly what Harley wrote here: 


<a style="font-family: 'Times New Roman'; font-size: medium; font-weight: normal; line-height: 20px;" name="start_28347.317402"></a>


"You can also have airflow, like a dryer, where it moves 180 CFM, but it is mass air flow [COLOR=#ffff00; background-color: #000000]very little suction because the air is being replaced as quickly as it is being removed.[/COLOR] The air flow carries out the damp warm air in a dryer, as is the air flow that moves the dirt off the carpet and into the capture system." 


 


Another way to look at it is when you first turn on a Kirby, and the fan starts to spin up, there is a brief moment of suction that starts the air moving through the machine. Once the Airflow reaches full speed, the suction drops off to a small amount<span style="font-size: 14pt; color: #ff0000;"> because the air inside the floor nozzle is being replaced as quickly as it is removed. [COLOR=#000000; font-size: 12pt]Once air is constantly moving at full speed, there is no more need for lots of suction. The reason why the Kirby and Royal have so much airflow is because the opening to the fancase is a full 2 inches in diameter compared to Dyson and similar machines which is between an inch and an inch and a quarter. The Bell Shaped nozzle amplifies the airflow as well. Read the posts above, there is a scientific formula that proves this.[/COLOR]</span>


 


 

 

[marcusprit]

That may be true but you still need the suction to get the air flowing

 

[marcusprit]

Air Watts = Vacuum suction (inches of water) x Air Flow (cubic feet per minute)/8.5Air Flow (CFM) = √13.35 X D2/Vacuum suction

 

[kirbysthebest]

but you can have suction without air flow

A dead suction, such as the demo where they stick an electrolux to the wall. There is no air flow.

When David Oreck picks up a bowling ball with his hand portable--no air flow.

A water pump is a good example: though I know it is not pumping water, it is moving fluid. Which air is a gaseous fluid. The pumps impeller creates a vacuum, whereas the ambient air pushes the fluid water up the pick up pipe, through the pump and out to the output. A water pump is limited to how much "vacuum" or suction it has due to the atmospheric pressure is what "pushes" the water up from the well when the pump creates the suction. Because it is limited to the atmospheric pressure wells deeper than 25ft, are not considered a shallow well and requires a different type of pump or submerged pump.

A submerged pump can be lowered into the well where it is closest to the water level and now you can go 200, 300, 400 ft or more and not be dependent on the atmospheric pressure, because the pump itself is "pushing" the water up the pipe to the surface.

I would equate the Submerged pump to a direct air machine where the business end is very close to the area of work, and the exhaust is pushed after that. This is why it doesn't have to "Suck" that hard, only move the air.

A Surface, or shallow well pump is very similar to a clean air machine as it has to suck the water through a tube, dependent on the atmosphere to push and there is only so much atmosphere, but then a short distance to exit.

All the pump has to do is displace the water and the atmosphere pushes additional water in it's place. This is the same with a suction cleaner. The spinning fan displaces air and since nature abhors a vacuum the atmosphere quickly replaces the air with more so a larger fan with a somewhat restricted intake will create a greater suction due to our good friend Bernoulli, but if you shut off the air flow the suction is only that of the displaced air and the atmosphere around it.

Now if you were to leave your water pump running and shut off the water valve, the pump would still be trying to displace the water, but with no where to go it would only cavitate within the chamber, but nothing would move no flow, no vacuum.

So in close, yes you are correct they are dependent on one another, but as indicated as flow increases suction drops as nature only allows so much atmosphere. As we restrict the airflow as through an old fashioned carburetor air horn vacuum increases, but air flow decreases.




[this post was last edited: 3/4/2015-14:43]

 

[marcusprit]

I agree with you. I read that very slowly

 

[kirbysthebest]

Marcus

This has been a good discussion, thank you for posing the question.