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."
