Loop tubing length question

[santiagodraco]

How much of a factor does the tubing length in a loop matter? I'm running my pump/res external (since it's an HTPC case) and want to locate the external unit further from the case so it's hidden away. To do this effectively (while keeping the res and pump level with the case) would require about 15-20 feet of tubing (rad/pump to case). Would this cause issues?

I'm toying with an alternate solution that would not require this kind of distance but would look much less elegant in the room but only want to take that approach as a secondary choice.

I also hard Cathar mention something about keeping the radiator low to the ground (I assume for cooler air). I was thinking of this as well but that would place the radiator about 4ft lower than the pump and the pc, would that be an issue?

I'm running the Laing DDC 3.1 that's from Koolance in the RP-1000 unit.

Thanks

[ColonelCain]

Hmmm... If you really want to do that, you are going to need a stronger pump.

On the other hand, this is what I saw from Petra's:

Max. Head Pressure (at 12V): 8.2 psig (18.91 feet - 5.76m)

It could be feasible.

[santiagodraco]

Hmmm... If you really want to do that, you are going to need a stronger pump.

On the other hand, this is what I saw from Petra's:


It could be feasible.

I guess that's what I'm wondering about, the "head" rating. Doesn't that refer to the amount of fluid that can be pumped vertical, without the pump failing to move the liquid? Or does it refer to the maximum length of line?

[jokester]

It's essentially the head of water that can be pumped vertically by the pump.

The pressure drop from a length of hose would be pretty minimal I would have thought, as long as it's on the level.

Jokester

[Martinm210]

Still working on a whole bunch of flow rate tests, but I did run component tests, and I found that:

At high flow rate 10' of tubing is close to the same amount of restriction as an MCW60 or an MCR320. It's a little more restrictive than it theoretically should be and not sure why. Almost no difference between 7/16" and 1/2" ID.

Also as far as pressure head and elevation, don't worry about it, doesn't matter in a close loop because the pressure energy of the coolant coming back down will power it up on the other side. This is potential energy and because it's always returning to the same point there is no potential energy loss, we only have frictional energy losses to deal with. The only way that could ever be an issue is if you exceeded the max pressure head rate when bleeding the system, and you could fix that by simply having a taller funnel..

[sick_g4m3r]

wait, if the pump and case is level then it wont make a difference. you'll be fine

[santiagodraco]

Sounds good. I'm actually waiting for some new Masterclear (sp) tubing to arrive next week. Going to replace all the tubing in the setup along with adding in some less restrictive connections (removing a couple of elbows for example).

I just did a "visual" test today with some sleeving over the tubing and painting the RP-1000's case black (it's silver originally). So far I like the look and might not go with the real long loop after all, unless I lower the radiator (it's just below the PC in back of the stereo enclosure.) Here's a shot of the setup:









Right now I'm using generic 3/8 pvc tubing with Swiftech coils under the black sleeving. Part of the issue I have with the tubing is that it was slightly deformed (somewhat oval) from being stored in a roll. I'm assuming the Masterclear doesn't have this issue. I kinda doubt it effects flow much, but we'll see.

[Martinm210]

Nice setup, you'll like the masterclear tubing.

I have both the masterclear and tygon R3603, and they are both great. The tygon is slightly softer so you don't have as much pressure on blocks, but from what I could see they both have about the same bend radius. The masterclear is actually nicer looking, tygon has a slight hazy opaque look to it in comparison.

[Mord]

Tubing lenght does matter! IF you use smaller ID tubing - under 10mm. I'm currently conducting some computer simulations on flow rate/pressure drop/ID/length.

So generally what kills the loop is not the blocks, rad or length - it's the ID. Don't use anything under 10mm. Another thing is the connections and splits - less = way better.

Just to give you an idea of how important the ID is:
blocks/rad: apogeegt, mcw60, heatercore (manufacturer stated or estimated pressure drop)
pump: Sicce NOVA - 1.6m H2O, 800l/hr
tubing: 8mm, 10mm, 11mm, 12mm, 13mm, 14mm (theoretically)
length: 0.95m, 1.3m, 1.9m
Simulation run with no connectors, barbs and so.

Here you go:



And with different pumps @ 0.95m tubing length:



And some calculations for the tubing only (no blocks, nothing):



Conclusions (WIP):
1. ID<10mm is an overkill!
2. ID>=13mm - enough. Bigger ID = nothing more.
3. 10mm<ID<13mm - length matters most! Every cm of it means less flow.


I will post all results soon, after a few more simulations.

ABYSS