Question Maximum radiator air pressure?

Apr 28, 2021
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Basically I'm planning on replacing the inadequate fans (sub 1mmH2O) on my radiator with something that can pull at least 6mm of water/~60Pa. One of the lower end ones I'm looking at getting is a 120mm fan that pulls 8.5mm/~84Pa, while I have a spare 120mm from some other equipment that pulls about 345Pa which I tend to think is too much... the question is, though, exactly how much is too much? The problem is that I haven't really found much info if any on the actual structural/mechanical limitations of consumer CPU radiators. My (probably irrational) worry is that if it ever became clogged for any reason the pressure might damage the fins, which I don't think is likely to happen since even 345Pa is really not a huge amount of pressure compared to like the 20kPa of a vacuum cleaner, but then again without knowing the specs or without setting aside an hour to (handwavily) calculate/guess it I have no idea.

Like I said though, it's probably irrational, but the idea of water spraying around in a computer case is not reassuring me. I mean, I would figure, seeing that the 8.5mmH2O fan and others are only $10-20, that manufacturers would use them instead of the wimpy 1-4mmH2O fans that they install on them, which just furthers my worries.
 
Apr 28, 2021
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Entirely unsure what you're asking here.
Fans move air, not water.
The manufacturers for fans often quote the max pressure that their fans can produce as millimeters of water displaced, or inches of water displaced, which can then be converted into pascals.... I'm asking what the typical maximum air pressure is for a consumer CPU fin radiator, the pressure beyond which said fin radiator's delicate fins and tubing become damaged, explode, or otherwise leak.
 

USAFRet

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Mar 16, 2013
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The manufacturers for fans often quote the max pressure that their fans can produce as millimeters of water displaced, or inches of water displaced, which can then be converted into pascals.... I'm asking what the typical maximum air pressure is for a consumer CPU fin radiator, the pressure beyond which said fin radiator's delicate fins and tubing become damaged, explode, or otherwise leak.
There is NO fan that will go in a PC that will damage or break the tubes/fins on a radiator.
None.

They move air, not liquid. And they certainly can't break metal.
 
Apr 28, 2021
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Frankly, air is actually a liquid, and my post has nothing to do with water, the only thing involving water is in the manner pressure is measured. Also, I oppose the idea that: "There is NO fan that will go in a PC that will damage the tubes/fins on a radiator." I guarantee you that if you seal the ends up on a radiator and introduce a negative pressure high enough, you will damage the fins and heat exchanger tubing, you really do NOT need that much of a pressure differential to cause damage if the materials used are not up to par for that added stress. The question is, and still remains, quite literally, what are the specs to which consumer radiators are built.

I have no intention of buying a radiator, chopping it up into little pieces, measuring the thickness of each part, finding out what alloys comprise it, and then modelling it with a litany of equations and calculus and even maybe some FEA analysis to find out something that honestly should be stated in the datasheets, which is either A: maximum tensile strength of the thin-walled tubing used, which I doubt is very high, or B: the maximum pressure through-put from one side of the radiator to the other IF there is zero airflow, IE: blocked intake. I want the worst case scenario.

If I cant get an actual answer for that, then what is the average thickness and diameter of the heat exchanger tubing in the radiator, because I am positive that it is not 1/2" schedule 40 pipe. I've seen copper and aluminum tubing with wall thicknesses as low as .01" and .003".
 

USAFRet

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Well yes, air can be considered a fluid.

The fans in the PC and attached to the rad are moving air past the fins. Not pumping air or fluid through the tubes.

and introduce a negative pressure high enough...
Which you cannot do with any fan on the consumer PC market.


A fan with the spec of "a 120mm fan that pulls 8.5mm/~84Pa" has NOTHING to do with the fluid inside the radiator.
 
Apr 28, 2021
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Well yes, air can be considered a fluid.

The fans in the PC and attached to the rad are moving air past the fins. Not pumping air or fluid through the tubes.


Which you cannot do with any fan on the consumer PC market.


A fan with the spec of "a 120mm fan that pulls 8.5mm/~84Pa" has NOTHING to do with the fluid inside the radiator.
I dont care about the 84Pa fan, I want to know the MAXIMUM limits of consumer radiators in general, and I am not talking at all about the fluid inside the radiator. I have no idea where you got that from, and I honestly don't know how to convince you that I am concerned about the AIR PRESSURE between the fan and the radiator exchange tubes if the radiator was CLOGGED or otherwise blocked. I am also not talking about consumer fans, I'm talking about industrial grade fans. In fact, I have some small axial DC fans (80-120mm) that can easily do 1.2kPa, at ~230cfm at 45dBA which is insane. I am also not talking about implosion or deformation due to a negative pressure INSIDE of the tube, I am talking about deformation or explosion from negative differential pressure OUTSIDE of the tube. For example: take an aluminum can with water/air in it, close it, and put it in a vacuum chamber. That is the kind of damage I am curious about. It's the same concept when the radiator is blocked from one side: you have thin walled cylinders with a water/dissolved gas mixture at some pressure at or above 1atm with a pressure differential outside that is less than the pressure inside the cylinders. What happens depends on the physical dimensions of the cylinder and it's alloy composition and as I said I have no intention of cutting one open to find out.

The answer to my question does not need to be that specific, just generalized. What are the stresses that they are designed to meet? What is the point in which enough deflection/damage occurs given the unknown dimensions of the tubing to render the radiator either ineffective, inoperable, or catastrophically destroyed. Some manufacturer, consumer or industrial, at some point, has HAD to have a datasheet with those specs mentioned. Someone knows how they are manufactured and the materials (tubing) that they manufacture it with, yet for the life of me I have yet to find any documentation anywhere as to that. It wouldn't take much pressure at all to deflect some thin walled tubing, even large hardened steel pipes deflect a considerable amount even with a 0.1PSI differential, aluminum even more so.
 

Darkbreeze

Retired Mod
They are designed to handle stresses FAR beyond anything ANY commercially available consumer OR industrial 12v fan including the 3000+ RPM variety sold by Delta, Noctua and others, could ever potentially present. So your question is, in reality, moot.

If the radiator were clogged, then your question would be ENTIRELY pointless, because a clogged radiator cannot provide ANY realistic amount of cooling capacity, and certainly not enough to afford even the slightest level of necessary cooling for systems in which this type of cooling might be necessary in the first place.

The AVERAGE mm H2O for a consumer 12v PC cooling fan is, there IS no average really, because it varies GREATLY from fan to fan and application to application. Many popular PC fans have less than 1mm H20 static pressure. EVGA sells 140mm 12v fans with 4.2 mm H2O static pressure, and Noctua has fans in it's Industrial iPPC series with 10.52 mm H2O on it's 3000rpm models. Delta probably has some in that range that are even higher. All of which would work fine on ANY modern PC radiator, without issue, so long as the loop is full of fluid and the fins are not clogged. If the fins are clogged then it doesn't friggin' matter what the static pressure of the fans are, you have a problem, and that problem is NOT going to be solved by having a fan with higher static pressure.

It's going to be solved by NOT HAVING IT CLOGGED in the first place, or cleaning it out.

Furthermore, you're rather borderline rude to a member, and a moderator no less, that was actually trying to help you. There is a line about dogs biting the hands that feed them somewhere, but it's likely not necessary anyhow.


For what it's worth, I disagree with you 200% in that I do NOT believe there are ANY consumer fans available in ANY size, 200mm or less, that would EVER be capable of causing damage to the fins or tubes on any modern PC cooling radiator. That's senseless, crazy talk.
 
Apr 28, 2021
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Again, we are NOT talking about consumer fans. That was NEVER the point of the discussion. The entire question was: WHAT ARE THE MECHANICAL LIMITATIONS OF COMMON RADIATORS, SPECIFICALLY THEIR HEAT EXCHANGE TUBING, WHEN IT COME'S TO PRESSURE. It's really that simple, and I know that there is someone out there who knows. As far as clogging goes, I am not talking about dust, I am talking about OBSTRUCTIONS in general. Furthermore, I want a worst case scenario.

As for being rude: I feel that having to restate the same exact question multiple times is ridiculous, never mind who I have to do it for, and at this point I am tired of restating it. I shouldn't HAVE to restate my question, and I find it rude to essentially force someone into that position, whether it's because the question was not read fully or otherwise. Again, it doesn't matter who it's in reply to. I feel as if I properly explained my question and worded it sufficiently to begin with.
 

Rogue Leader

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Again, we are NOT talking about consumer fans. That was NEVER the point of the discussion. The entire question was: WHAT ARE THE MECHANICAL LIMITATIONS OF COMMON RADIATORS, SPECIFICALLY THEIR HEAT EXCHANGE TUBING, WHEN IT COME'S TO PRESSURE. It's really that simple, and I know that there is someone out there who knows. As far as clogging goes, I am not talking about dust, I am talking about OBSTRUCTIONS in general. Furthermore, I want a worst case scenario.

As for being rude: I feel that having to restate the same exact question multiple times is ridiculous, never mind who I have to do it for, and at this point I am tired of restating it. I shouldn't HAVE to restate my question, and I find it rude to essentially force someone into that position, whether it's because the question was not read fully or otherwise. Again, it doesn't matter who it's in reply to. I feel as if I properly explained my question and worded it sufficiently to begin with.
You are wrong.

You're insisting on an answer to your question that only the product designers could likely answer. Its not a published number because there is no situation other than putting the radiator in a press that it would EVER see those kinds of conditions.

With great certainty I can tell you there are NO fans consumer or industrial of the size that would fit on the radiator that could cause ANY deflection or damage whatsoever, even if the radiator were fully clogged.

If you need more information than that you should contact the manufacturer directly.
 
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Darkbreeze

Retired Mod
With great certainty I can tell you there are NO fans consumer or industrial of the size that would fit on the radiator that could cause ANY deflection or damage whatsoever, even if the radiator were fully clogged.
Agree, concur, and this was the whole point and only reason I replied previously. This, is the exact answer I should have said, but didn't.

Furthermore, I doubt there are ANY fans, period, that could be mounted to any radiator intended for use on or in a personal computer, that could damage it. Period.
 
Again, we are NOT talking about consumer fans. That was NEVER the point of the discussion. The entire question was: WHAT ARE THE MECHANICAL LIMITATIONS OF COMMON RADIATORS, SPECIFICALLY THEIR HEAT EXCHANGE TUBING, WHEN IT COME'S TO PRESSURE. It's really that simple, and I know that there is someone out there who knows. As far as clogging goes, I am not talking about dust, I am talking about OBSTRUCTIONS in general. Furthermore, I want a worst case scenario.

As for being rude: I feel that having to restate the same exact question multiple times is ridiculous, never mind who I have to do it for, and at this point I am tired of restating it. I shouldn't HAVE to restate my question, and I find it rude to essentially force someone into that position, whether it's because the question was not read fully or otherwise. Again, it doesn't matter who it's in reply to. I feel as if I properly explained my question and worded it sufficiently to begin with.
Let me put it this way, I always clean my radiator with a shop compressor with more than 100 ponds pressure and never damaged it,
 

faalin

Judicious
The fact that i ran a push pull with Scythe Ultra Kaze 120mm fans 133.6 CFM on 2 Danger Den Black Ice Extreme 480mm radiators for a few years, i think you will be fine.

Computer had 21 Kaze fans in it and yes it sounded like a jet engine when you turned the computer on.
This was my side panel, 16 fans in push/pull, 4 on the top with a 240mm rad, and a single exhaust in the rear.
 

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