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Discussion Starter · #1 ·
Hi Dude's,

A few simple questions.

What would be considered a Bad/medium/good and excellent flow rate (G/M please)?

What would be considered a Bad/medium/good and excellent Pressure level (PSI please)?

How hot is your liquid coolant compared to your CPU temp? (for all you who have the necessary temp sensors)

Thanks,

DD
 

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There is not really a guide to how much flow you need, although 1.5gpm seems to be a fairly common benchmark, and after this, increased flow has very little effect.

Pump pressure is usually measure in how far liquid can be pumped vertically. The best mainstream pumps for head pressure are the Laing DDC pumps, which are usually rebranded to Swiftech MCP350 and 355. Their head pressure is around 3 metres I believe (with the stock top) and this is generally recognised to be excellent.

As for your third question, I'll leave it to someone else because I don't have a clue
 

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as mentioned minimum flow should be around 1.5gpm.

as for head... aaron is a bit wrong on the head the 355 can shoot up to.. its actually 6M or 20ft.
great little suckers. as for the D5..that one is at 3M..

i just realized you're talking about pressure.. the D5 has 50PSI and the 355 has 20PSI..
 

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Like Naf and th eother fellow said I'd try to stick around 1.5GPM, you could probably get by with a little less since some of the newer CPU blocks aren't as flow dependant, but thats still an easily obtainable GPM so I'd stick with it.

PSI is a measure of back pressure on your loop, so it would depend on what all you have in your loop, I run a PSI gauge right after my pump and in a CPU only loop with the old high performance 18W DDC pumps and a 240 BIX rad I was getting around 5PSI on back pressure. Hit my camera icon and look at my pic's, I have th egauge on several config's so that will give you an idea.

Your rad out to room ambient delta I'd keep at least 5C and under for good OC'ing performance.

Coolant to CPU delta I've had from a 1c rad out above ambient with a 14-18C above room ambient load. And around a 2C rad out to18-20C above ambient load. So much of the time I'm running TEC when I'm on WC'ing and it's been a long time since I just ran straight water that I just don't remember exactly what it was. Take a look in my sig at that shroud testing link, it has a lot of rad out to room ambient and load temp's. While the rad temp's would be valid in that with TEC the rad out to CPU load may be kind of skewed, something to look at though..
 

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Quote:


Originally Posted by junkyard00000
View Post

Why isn't there a correlation between pressure in PSI and head pressure?

PSI is a outward measurement of force. Head is a loops energy and velocity, that is what overcomes the restriction in your loop, that's why you'll get better flow with a pump that has higher head. Head is measured by how high a column of water it can push straight up, that's a pumps shut off head measurement.

Quote:


A pump does not create pressure, it only creates flow. Pressure is a measurement of the resistance to flow.

Source..Centrifugal Pumps ...Head can be converted to a PSI reading if you wanted to...Converting Pump Head to Pressure

So from that quote above you can see why using the same pump the PSI will be higher depending on how much restriction there is in the loop or how viscous your coolant is. The head is a constant, it's max is at the pumps outlet and returns to 0 at the inlet. PSI is variable depending on loop config and coolant viscosity.
 

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Discussion Starter · #8 ·
Quote:


Originally Posted by aaronb33
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There is not really a guide to how much flow you need, although 1.5gpm seems to be a fairly common benchmark, and after this, increased flow has very little effect.

Pump pressure is usually measure in how far liquid can be pumped vertically. The best mainstream pumps for head pressure are the Laing DDC pumps, which are usually rebranded to Swiftech MCP350 and 355. Their head pressure is around 3 metres I believe (with the stock top) and this is generally recognised to be excellent.

As for your third question, I'll leave it to someone else because I don't have a clue


Cool, This helps allot. now I know what my goal needs to be if it comes to flow rate.
 

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Discussion Starter · #9 ·
Quote:


Originally Posted by ira-k
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PSI is a outward measurement of force. Head is a loops energy and velocity, that is what overcomes the restriction in your loop, that's why you'll get better flow with a pump that has higher head. Head is measured by how high a column of water it can push straight up, that's a pumps shut off head measurement.

Source..Centrifugal Pumps ...Head can be converted to a PSI reading if you wanted to...Converting Pump Head to Pressure

So from that quote above you can see why using the same pump the PSI will be higher depending on how much restriction there is in the loop or how viscous your coolant is. The head is a constant, it's max is at the pumps outlet and returns to 0 at the inlet. PSI is variable depending on loop config and coolant viscosity.

The engineering toolbox Rocks !!! thanks Ira, very useful as always.
 
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