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Are these pressure calculations for WC accurate?

Yes, I've read the sticky, I found a link on there leading to charliehorse55's WC thread on another forum.
Over there he has made a small list like so:

Quote:
Pressure Drop figures for components
Radiators: 0.20 PSI each (the size of the radiator has no real effect)
CPU Block: 1.1 PSI
GPU block: 0.9 PSI
Motherboard block: 2.0 PSI (fullcover)
Fittings: 0.3 PSI for the entire loop
Tubing: 0.5 PSI per meter (3.3 feet)
Reservoir: Negligible


I'm on the final stages of building my PC, compiling a list of WC components and for the pressure I've calculated 11.8 PSI total for my entire loop.
That's 1 Radiator
1 CPU block
3 GPU blocks
1 motherboard block (it's doesn't cover the mobo head-toe like the asus motherboard armour)
2 Metre tubing (probably will only use one metre, still working on this)
16 fittings

I suppose my main question is do the fittings cause any restriction if they're clamped at the base of the input/output for any blocks?

Since I'll be using high quality tubing (ones that curve without closing on its self) I wont be using any fittings to co-ordinate the tubing, so was wondering if I should calculate the fittings PSI, even though they're only keeping the cable attached to the blocks.

I'll be using the fittings like this: http://cdn.overclock.net/4/47/479f63e8_vbattach190468.jpeg
At the base of the blocks, and not to curve the cable.
11 answers Last reply
More about pressure calculations accurate
  1. Yes, his calculations are pretty much as close as you are going to get without a labcoat and lots of equipment.

    Anything in the loop is going to introduce flow reduction due to restriction of some sort.
  2. Even the fittings used to tighten the cable to input/output?
    Would a fitting still have a 0.3 PSI restriction if it's used to connect the tubing to the components?
    If so, I'm getting 4.8 PSI from just the basic fittings needed to clamp the tubing to the components.
  3. Btw I'm just gonna use the fittings as clamps, to clamp the tubing onto the components, would it be better to use clamps instead of fittings?
    Would I need to accommodate PSI for them?
  4. Oddly enough I can't edit my own messages, but the Laing D5 Strong (8-24V DC Pump) is being rated as pumping 50PSI. Surely this is not correct?
  5. This only applies to components that come in contact with the water- a fitting is a fitting. A compression fitting has 2 components but is a single fitting. The threaded 'clamp' portion doesn't have any impact on the flow, but the rest of the fitting does.

    Why wouldn't that be correct? It likely is a max value, but sounds about right, but I've seen some that range it from 25psi - 50psi. I wouldn't worry that much about it.
  6. On this guide it says
    "Now that you have the total pressure drop for your loop, find a pump that can handle at least that much pressure at 1 GPM of flow."

    So I don't think that pump will hit 50PSI at 1 GPM of flow.
    Is there a way to calculate this?
  7. You'd actually have to know exactly how much pressure drop you'll encounter based on hardware you don't currently own with the data estimated about pumps in question.

    To be honest, I would run 2 DDC pumps instead of a D5 if I were you. They run a higher rated head pressure even though the flowrate is lower than a D5. However, in restrictive loop, head pressure > flow rate.

    Look into a D5 with aftermarket top, MCP35x (with/without top) or even dual MCP355's.
  8. You would have to know if it's a Centrifugal or Reciprocating pump
  9. http://www.engineeringtoolbox.com/darcy-weisbach-equation-d_646.html, unless you need a specific heat dissipation. Dual pump in single top is good investment ( if one fails, the other could still save from heat damage). Don't get confused with flow rate (Q) and pressure (P), just have your loop free from leak and kink, its the radiator's heat dumping will matter the most, don't trust vendor's heat dissipated claim, always get bigger radiator that fits your case, if that's your loop setup then a triple 120 mm fan (360) radiator minimum or a dual 140 mm fan (280) in push-pull configuration ( assumed 200W CPU and 200W GPU plus 80W choke TDPs) . About your calculated pressure drop... I'd say a D5 Vario setting 4 is safe enough, or 80% DDC, below that would make radiator become less efficient because not enough warm water to be cooled. If your pump able to move half gallon per minute, its a worthwhile spending, if you find your CPU and GPU temperature as hot as their stock cooler with your current pump, try different placement/loop order, I've tried it myself, got me 6 to 9 C degree cooler.
    A lot more to be count beside the shape of fittings, fluids tend to move faster on mild elbow space, avoid 90 deg fittings as much as possible, more from https://martinsliquidlab.wordpress.com/2013/01/05/elbow-impacts-on-pump-performance/.
  10. You're looking way to much into the math for this. A single DDC would run your planned setup. I'm using two MCP35X pumps in my custom loop. When drain/filling, I pump plenty of coolant using a single pump while leaving other unplugged. Until my recent 1080 upgrade, I had 2 GTX 970s and blocks in my loop. To sum up, I have 2 360 rads, a 240, CPU block, Motherboard VRM block, and had 2 GPU blocks. I also have a double-wide case with tubing running on both sides(several feet), and tons of compression fittings, ect. Plenty of coolant/movement in reservoir. I went with two pumps to lower noise and RPM, heat, power draw, increase pressure, and have a backup.

    Also, you mention a single radiator for your setup. Is this correct? If so, is it one of those jumbo external models?
  11. Thread was inactive for 4 years until today.

    Closing.
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