# a



## Scully (Dec 3, 2011)

a


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## joecaption (Nov 30, 2011)

It's magic.
http://www.ehow.com/info_12076432_shop-vacuum-work.html


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## Scully (Dec 3, 2011)

joecaption said:


> It's magic.
> http://www.ehow.com/info_12076432_shop-vacuum-work.html



the link doesn't answer my question.


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## jschaben (Mar 31, 2010)

Scully said:


> the link doesn't answer my question.


I can't get technical because... well, I can't. It's just that the bag is porous enough to allow air flow. That's why your suction falls off as the bag fills. Sorry, best I can do.


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## Oso954 (Jun 23, 2012)

The filter bag, is just a bag shaped filter. It stops dust and lightweight debris from entering the fan/motor area, while letting air flow thru it.

The lid of the shop vac makes an air tight seal on the bucket. The motor/fan pulls air out of the bucket, creating a low pressure area (partial vacuum) in the bucket. Outside air rushes up the hose attempting to fill the low pressure in the bucket. (The fan is sized to eject more air than the hose/inlet will let in.)

The air inrush, pushes (not pulls) dirt and debris up the hose. The dirt/debris drops to the bottom of the bucket.

If you had a solid connection between the hose inlet and the fan area, the dirt/debris would run thru the fan, and eject out the exhaust outlet.


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## Scully (Dec 3, 2011)

Oso954 said:


> The filter bag, is just a bag shaped filter. It stops dust and lightweight debris from entering the fan/motor area, while letting air flow thru it.
> 
> The lid of the shop vac makes an air tight seal on the bucket. The motor/fan pulls air out of the bucket, creating a low pressure area (partial vacuum) in the bucket. Outside air rushes up the hose attempting to fill the low pressure in the bucket. (The fan is sized to eject more air than the hose/inlet will let in.)
> 
> ...



thanks for the explanation, Oso954. if the bag acts as a filter for the drum so dirt doesn't fly out of exhaust, then the hepa filter on the motor/fan prevents dirt from flying out of motor/fan?


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## ddawg16 (Aug 15, 2011)

What really happens is that when you turn on the shop vac, the motor pushes air out of the vacuum. When this happens the pressure inside drops. Because the pressure outside the hose is greater, atmospheric pressure pushes air down the hole...this pressurizes the bag..and the motor again pushes it out of the vacuum.

Because the holes in that bag are smaller than the dirt, but bigger than air molecules, air goes through, but not the dirt.


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