Pressurized or ambient relief?

[NavyDood]

Won't a water cooled system pressurize from thermal expansion of the h20 as it heats up? Or is it ventd to ambient pressure?

Or am I just missing something here?

Jim

[bigben2k]

Welcome to ProCooling!

I guess plumbing isn't your field? In most systems, there's some kind of air leak, allowing for expansion. As you can imagine, it's really hard to keep something perfectly sealed.

Otherwise, the expansion of water over the temperature range that's typical, would amount to a maximum of 5 drops of water, which most systems should be able to handle.

[NavyDood]

Thanks for the welcome.

I'm piecing a water cooling project together slowly. Just trying to get all my ducks in a row before I totally plunge in.

Wouldn't Venting the reservoir to ambient be a good thing to aid in bubble reduction?

I'm making my own reservoir out of Copper. Just another way of convection coling.

Jim

[Alchemy]

Originally posted by bigben2k
Otherwise, the expansion of water over the temperature range that's typical, would amount to a maximum of 5 drops of water, which most systems should be able to handle.

. . . yeah.

English or metric drops, Ben?

Sigh.

Anyway, the deal with liquids is that they do expand very little with temperature. If they are kept perfectly sealed, then yes, they will create some impressive pressure - fluids don't like to be compressed. But, as you say, only a little bit of breather room - a small hole in a reservoir, or even a totally sealed system with ~10 cc's of air somewhere for the water to compress - will keep pressure in the system from getting high enough to burst anything.

This is, of course, barring extreme cases where there is a pump failure and one particular part of the system heats up enough to either melt or burst the tubing near a waterblock.

In a totally sealed system such as an in-line system with no air in a reservoir or trap of some sort, it's at least possible that the shift in temperature from ambient to operating, which could be as much as 20 degees C, which would translate to an increase in volume of 0.6% at constant pressure or an increase of pressure of 2000 psi at constant volume.

The flexibility of the tubing in the system will probably account for most of the volume change and prevent a pressure increase anywhere near that high, but the fact remains that if water is highly constrained, like in a system with very inflexible tubing and no airspace, water can burst a WC system just by being heated a few degrees.

Fluids do not like being compressed. Give your precious fluids room, and you can maintain purity of essence.

This has been a public service announcement.

Alchemy

Cite: NIST Webbook http://webbook.nist.gov/cgi/fluid.cg...85&Action=Page

[bigben2k]

You ought to know the difference between an english or metric drop, Alchemy... (for the rest of us: there isn't any).

This is a figure I calculated based on data available from a machinist handbook, 26th ed (for those who have it), and actually, it's for a full gallon of water, not a typical 1/2 gallon (usually less), and the temp difference is 20 deg C, which is far higher than most of us encounter.

Do you want me to dig up the post?

[Cova]

My system is as sealed as I can get it - no res (well - a T-fitting with a few inches of 3/8" ID Tygon for airtrap - VERY small res), lots of teflon-tape at the top of the air-trap where I screw a cap onto a barbed->threaded adapter in the top of the hose. Every other joint/barb/etc. is below fluid level and I don't have any leaks, so I assume they are sealed. Tygon is pretty stretchy stuff - the tubing can expand a bit if the pressure inside increases by a few drops (probably only 1 or 2 drops in my case as I have a very low volume of coolant).

Actually - to really test my system for leaks, I grabbed one section of tubing with both hands and squished it flat while the cap was on and the pump was off. This would have increased internal pressure by a LOT more than I will ever get from heat expansion, and I didn't even get a single drop of coolant leaking from any joints.

Even if the whole system was copper pipe and sealed, I think you'd need more than thermal expansion to break anything. You'd have a hard time getting so much air out of the system that there aren't a few bubbles somewhere that can't take a bit of compression.

[bigben2k]

Good test Cova (gutsy!). I'll be testing mine with air pressure, using the tee into which I gooped and air tire valve. I just wish I had a pressure gauge handy.

Like Alchemy said: 10 cc of air in the loop will take care of it.

[Cova]

Well I don't think it was too gutsy - if you've used it at all you should know Tygon really is stretchy stuff. Then again, it took me almost an entire day to get the 3/8" ID tube onto all the 1/2" OD barbs in my system (it makes a TIGHT fit - I don't use any clamps or anything). After practically taking the skin off my fingers pushing tubing onto barbs I didn't even leak-test it before putting it in my computer. And that pressure-test of squeezing flat as much tubing as I could fit in my hands I did while it was installed in the computer too.

[redleader]

Mines fairly airtight. It had to be since I ran alcohol for a while. After a few months I opened it while the water was warm and got a slight "pop" sound when I pulled the top off.

[Marci]

cor.... u love to overcomplicate stuff here dontcha!

[hara]

This is just like in a car cooling system, on a smaller scale. No need for discussions about it IMO.

[Marci]

dunno but the topic title sounds more like it should be relevant to masturbation...