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tubing question

N

nchell

n00b
Joined
Jun 29, 2006
Messages
24
maybe it sounds a bit silly,
but why 1/2" tubing is better than 3/8" as 3/8" is better than 1/4"?
 
If you have two surfaces rubbing togeather (rubber and water), there is something called keinetic friction. As the ratio of surface area (of rubbing) to (volume of water being moved) increases, there is more friction and therefore the water moves slower. Another aspect is the "U-turns". If water is moving in a small tube and does a U-turn, it'll create more friction than a big tube with the same radius U-turn.


One thing going for small tubing though (which makes a non-noticable difference) is that as the speed of the water/rubber contact increases, the keinetic friction coefficient drops minimally, but that is negligible even when making precice estimates.
 
lol, scientific explanation makes it more complicated.

hartman's explanation is WAAAAY better.

larger tubes= more water/ waterflow, more waterflow =more cooling.
 
Cons: Bigger tubing is usually thicker = harder to make tighter corners, also makes for hard installation
 
You want as high water flow as possible and highest pressure in the waterblock(s).
Smaller tubing has more surface are per unit of cross section area so will have higher friction.
This will result in less water passing at any point and will cause a slight pressure drop at the water block(s).

Its easy to think that because water will be flowing faster through thinner tubes that it will help.
This is untrue, the water does move faster in thinner tube but the amount of water passing any point will be slightly less.
Its a bit like running water out of a tap. If you put your thumb over the end of the tap so the water shoots off, the water is going faster but there is less water flowing out.
 
I used 1/2" tube with a Ford Sierra heatercore and had a phenomenal water cooler for very little cash.

As pointed out already, thicker tube is not as easy to route so choose the tubing wisely.
I used ye basic 1/2" tube from a hardware store with no problems but my pump and radiator were outside the case so I didnt need to make tight turns.
 
i used 1/2 tubing, i made turns using coolsleeves. it's all internal.
1/2 tubing, storm rev2, dd5 pump, 240mm Gts.
AllDone.jpg
 
Quote:

"This is from Cathar

Quote:
Been rolling the whole tubing size idea around in my head, and thinking about trade-offs and the like.

I like the idea of 3/8" ID tubing, but I just can't shake the feeling that for >4LPM that it starts to become an increasingly significant source of restriction for those who wish to make use of strong pumps capable of pushing the higher flow rates. It's not that 3/8" tubing is bad at all for coping with moderate flow rates, it's just that it could be better. For example at 6LPM, 7' of 3/8" ID tubing is offering pretty close to 1mH2O of pressure drop all by itself.

But 3/8" is attractive because it's very light, and it bleeds air-bubbles fast.

1/2" tubing is fat and unattractive. Unless flow rates are getting past the 6LPM mark, air-bubbles don't bleed very well. It's heavy, and it requires fairly thick walls (1/8") before it can turn good radii without kinking, but this wall thickness comes at a cost of making it stiffer to turn, thus putting more leverage on the water-block's all important thermal contact. However, it takes around 13.5LPM before 7' of 1/2" ID tubing offers 1mH2O of pressure drop, so really it's almost overkill.

So I looked to the middle-ground, that being 7/16" (~11.1mm) that has 3/32" wall thickness for a total of 5/8" OD. Per length of tubing it's about 2/3's the weight of the 1/2" ID (3/4" OD) tubing. Being a thinner ID it is able to be bent into tighter radii without kinking, allowing for the use of the 3/32" wall thickness, which means that it also becomes easier to turn those radii. It offers 1mH2O of pressure drop at 9.5LPM for a 7' length, which pretty much puts it still as a very attractive offering.

Then I took into account stretching the 7/16" ID tubing over 1/2" OD fittings (barbs) with 10mm ID orifices. Due to the "lip effect" the 1/2" ID tubing actually offers nearly 3x the transitioning resistance at fittings as the 7/16" tubing whose ID more closely matches the ID of the fitting. Over a typical full system when fitting resistance is taken into account, the 7/16" ID tubing offers almost the same amount of tubing + fitting resistance as the 1/2" ID tubing.

Results were obtained using the pressure drop calculator from http://www.pressure-drop.org.

This all got me to thinking that really what us 1/2 inchers may really want to be doing is fitting 3/32" thickness walled 7/16" ID tubing over our 1/2" barbed systems, and pretty much be enjoying no extra system resistance, but gaining the benefits of lighter tubing that is easier to bleed (bleeds very well at a predicted ~5LPM), easier to bend, isn't as bulky, "hangs" less off water-blocks, and is significantly cheaper due to less wall material being used."
 
Good read.
I'm happy as I am so theres no real motivation to change here :)
I'll bear it in mind though.
 
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