Long shop vac hose??

Re: Long shop vac hose??

>So I  would  like to setup a dedicated vacation in the garage  for vehicle maintenance.  Thinking that a smaller  diameter  hose in a long length.  

The larger the diameter and length of the hose, the less vacuum suction there will be, as the air will take up more space in the hose, reducing the amount of suction. Conversely, the smaller the diameter and length of the hose, the greater the vacuum suction, as the air is given less room to expand, creating a stronger vacuum.

I think the relationship can be calculated using

Suction = Volume of air in the hose / (hose diameter^2 x hose length)

P.S. Won't your wife be upset if you take a permanent vacation in the garage?

Re: Long shop vac hose??

I thought that you want a large diameter hose to minimize vacuum loss by friction and an end fitting that has a necked down end to increase the vacuum.

Re: Long shop vac hose??

>I thought that you want a large diameter hose to minimize vacuum loss by friction and an end fitting that has a necked down end to increase the vacuum.

Hmmm...I think friction would increase with hose length and diameter, just as with fluid dynamics.

In inviscid (no friction) fluid dynamics, necking down would create a Venturi effect, an increase in velocity and decrease in pressure, creating more "suction" at the restricted point. I imagine it would be similar with air, which, unlike fluids, is compressible, so the math would be a bit different.

But that restriction will also restrict the amount of airflow back to the collection point, meaning there may be insufficient airflow through the Venturi to carry heavier things back to the collection point.

https://www.engineeringtoolbox.com/vacuum-pipe-line-pressure-drop-d_1197.html

This is not my area of expertise and I'm just shooting from the hip here. I think a lot of the calculations used by plumbers would apply here, especially those used in designing sewer drains which need to carry solids, if anyone is good at that.