The Sience of Suction

mickyd · Post by **mickyd** » Thu Apr 30, 2009 3:43 pm

guitarnut wrote:Got it. Thanks! I didn't know that would happen.

Peace,
Mark

wow, you updated in the nick of time. Now your safe AND we can say you are officially a full blooded 100% part of this great forum. Congrats and glad to have you.

Two other tasks
1. Place your user name logic in this post
2. Reply to this poll survey. Make sure to look at the map in first post before you vote.

JPG · Post by **JPG** » Thu Apr 30, 2009 6:18 pm

guitarnut wrote:Got it. Thanks! I didn't know that would happen.

Peace,
Mark

You CAN believe you CANNOT believe EVERYTHING Mike says.

mickyd · Post by **mickyd** » Thu Apr 30, 2009 6:47 pm

JPG40504 wrote:You CAN believe you CANNOT believe EVERYTHING Mike says.

Hey Hey....Don't tarnish my pristine image. I have a reputation to withhold in this loving group you know

JPG · Post by **JPG** » Thu Apr 30, 2009 7:31 pm

mickyd wrote:Hey Hey....Don't tarnish my pristine image. I have a reputation to withhold in this loving group you know

I am only reinforcing what we already know!:D

dlbristol · Post by **dlbristol** » Mon May 04, 2009 11:50 am

I am going to try to exploit some obvious expertise here. I have a dust collector with the 4 in intake. I have the 4 in hose on the machine and reduce it to 2.5 at the saw, planer or what ever. Would it make any difference if I reduced the hose at the collector housing and used a 2.5 in hose? What does The step up in radius do at the end of the hose, and would it make any difference if the step up happened at the collector? My guess is not much, but fluid mechanics and physics are strange beasts with many variables.

On the planer, it seems to work well collecting chips, and dust. On the saw, it seems to leak some dust. There is nothing I am really concerned about, but maybe I can get better results.

A 2.5 in hose would be easier to move around.

JPG · Post by **JPG** » Mon May 04, 2009 12:39 pm

dlbristol wrote:I am going to try to exploit some obvious expertise here. I have a dust collector with the 4 in intake. I have the 4 in hose on the machine and reduce it to 2.5 at the saw, planer or what ever. Would it make any difference if I reduced the hose at the collector housing and used a 2.5 in hose? What does The step up in radius do at the end of the hose, and would it make any difference if the step up happened at the collector? My guess is not much, but fluid mechanics and physics are strange beasts with many variables.

On the planer, it seems to work well collecting chips, and dust. On the saw, it seems to leak some dust. There is nothing I am really concerned about, but maybe I can get better results.

A 2.5 in hose would be easier to move around.

You have not indicated the lengths of the 2.5" and 4" before and the 2.5" after. The difference in static pressure drop between the two options will determine the degree of satisfactory performance. The 2.5" MAY maintain a higher velocity(all things being equal of which the static pressure drop will NOT be equal). Hope that makes sense!

dlbristol · Post by **dlbristol** » Tue May 05, 2009 2:00 am

I was assuming that I would use the same 8-10 foot hose length.

2manband · Post by **2manband** » Tue May 05, 2009 9:04 am

dlbristol wrote:I am going to try to exploit some obvious expertise here. I have a dust collector with the 4 in intake. I have the 4 in hose on the machine and reduce it to 2.5 at the saw, planer or what ever. Would it make any difference if I reduced the hose at the collector housing and used a 2.5 in hose? What does The step up in radius do at the end of the hose, and would it make any difference if the step up happened at the collector? My guess is not much, but fluid mechanics and physics are strange beasts with many variables.

On the planer, it seems to work well collecting chips, and dust. On the saw, it seems to leak some dust. There is nothing I am really concerned about, but maybe I can get better results.

A 2.5 in hose would be easier to move around.

I'd go with the larger diameter hose and then a reduction fitting on the intake end - as you're doing now. That should result in less frictional loss than going with a smaller hose and a reduction fitting on the dust collector end.

JPG · Post by **JPG** » Tue May 05, 2009 1:14 pm

dlbristol wrote:I was assuming that I would use the same 8-10 foot hose length.

2mb is correct. The 2.5" hose will drop static pressure MORE than the 4" hose of the same length. That being said, the 2.5" may work satisfactorily.

Using the info from nick's sawdust session on this subject, The SP drop for the two different sizes are:

2" x 10' = 1.2

4" x 10' = .7

This would indicate only reduced SP of .5! Hardly enough to affect the performance.

IMHO Go get a 2.5" x 10' hose. GOOD LUCK

dlbristol · Post by **dlbristol** » Fri May 08, 2009 12:09 am

I played with Nicks formulas as well and came up with the same numbers. Since it makes very little difference apparently, I will stay as is and spend my money on something else. I did try an experiment with a clean up of chips on the floor, and the 4 in hose worked better than the reduced 2.5 did. Not enough to temp me to take off and put on the reducer! I suspect that the issue for my situation is that the length of the hose is not enough to produce any real advantage either way. If I was doing a collection system, the difference would be much greater. Thanks

Shopsmith Forums

The Sience of Suction

4 to 2.5 reduction

Hose length.

Thanks