Does Size Really Matter? (Coolant Lines)

[GTXJackBauer]

The loop will eventually bleed out so I don't think that is the issue. I posted that link to show the loss of temp (0.05) while using a angle fitting. Now if you multiply that for the rest of the loop and lets not forget the blocks and the rads, it not as bad as some people think it is because once you're loop is in the 1.0-1.5 GPM constantly, you're good to go because presumably, you're running a single premium pump.

 

[fruitbatmoon]

No it doesnt in actually physical temps.. size of tubing doesnt really matter in reality you might get 0.5 differential

 

[Conumdrum]

Just one thing to keep in mind if opting for an elbow right at the imput side of a pump is that in some cases this can lead to cavitation.

The sharp change in direction right at a pumps input is usually not the best option. On the output side is ususlly quite OK though.

In the pump building world etc yes, it is a bad idea to have a 90 as an inlet. In our loops it doesn't seem to be a problem though. Probably our low flow and low pressure helps. I have seen a dual pump loop using thin wall tubing collapse at the inlet though.

 

[HankB]

I'm pretty much a noob when it comes to cooling systems but less so when it comes to pipe flow calculations (having worked as a "combustion engineer" at a steel mill in a previous life.) One of the things that struck me was the additional resistance added by valves and elbows. I found some information on this at https://neutrium.net/fluid_flow/pressure-loss-from-fittings-equivalent-length-method/. Scroll down to the chart and see that a 90° "standard" elbow is equivalent to a length of straight tubing 30 diameters long. For 1/4" tubing that would be 7 1/2". That assumes that the elbows are "standard" which is a piping specification. I have no idea if the elbows used for PC cooling are standard. If I google "standard pipe elbow radius" the pictures I see show something that looks like it has a lot longer radius than the elbows I see used in PC cooling systems. As the radius goes down, the relative resistance goes up. A lot.

I suspect the pumps are not normally operated in the range where cavitation is a concern. You need a drop of several psi at the inlet (relative to atmospheric pressure) before the pump is close to cavitation.

I would opt for flexible tubing where curves are long and sweeping and will reduce the effect on flow rates. Given sufficient diameter (and from one of the other threads anything from 1/4" and up is good) a few elbows won't have a significant effect.