Smell of Water-wetter - Page 2

bigben2k · 07-13-2002, 09:56 AM

Thanks Nemaste, that was very usefull!

creature: You're moslty right. All forms of tubing eventually dry up, and/or decompose, but that usually take a long time, unless it's accelerated by thermal cycling, and chemicals.

In your particular case, you are experiencing galvanic corrosion, which is partly delayed by the use of water wetter, but still there nevertheless. Since tubing has a porous surface (microscopically), it will very easily pick up that oxide, and change the color of your tubing.

As for your T's, you should give some serious thought to replacing them with PVC types, or at least the brass ones, without the coating. Your coating here is probably what is causing most of your corrosion, as your CPU and RAD are mostly OK together.

Silicone is better because it's relatively inert, but worse because it allows coolants to evaporate, right through the silicone walls (hence the discoloration of silicone tubing, with water wetter, and an unexplained loss of coolant).

Tygon is a chemically neutral variant of vinyl tubing, but like all vinyl tubing, is heavier than silicone, so not so much a good fit for an RC airplane (a hobby of mine as well).

gmat · 07-13-2002, 01:12 PM

Nemaste silicone will lose coolant through its walls because it's microporous. And it's *not* chemically inert... But like bb2k said it has other advantages.

the creature · 07-14-2002, 04:17 AM

Quote:

Originally posted by bigben2k
As for your T's, you should give some serious thought to replacing them with PVC types, or at least the brass ones, without the coating. Your coating here is probably what is causing most of your corrosion, as your CPU and RAD are mostly OK together.

Sad, they where so exspensive.
Where is the best place to buy those in PVC?

kibbler · 07-14-2002, 07:39 AM

I usually go to mcmasters.com. Since you're in Norway, that might not be the most convenient. Any thorough enough hardware/plumbing store should have them in at least several diameters

bigben2k · 07-14-2002, 10:00 AM

Prettu much anywhere: plumbing/hardware store, maybe even a pet store.

Sorry that you got jipped there, it seems to me like the guy who sold you those things was just out to make a buck, and saw someone (you) that was willing to throw some money at the problem.

pHaestus · 07-14-2002, 11:50 AM

At the concentrations of water wetter we work with, I seriously doubt that it is damaging to tubes. The pink dye that Redline adds will be absorbed by silicone, but the surfactant (and the slightly alkaline pH) should remain in the water and do its job of lowering surface tension and (somewhat) inhibiting corrosion. Vinyl hose would be at a greater risk IMO because I don't think it is particularly resistant to basic pH. However, this would only be a problem if you poured the water wetter into a fill line as a concentrated solution. Dilute it before adding it to the loop and I don't see why it would be a big problem.

Have access to a microscope in a biology lab? Would be interesting to just cut open the tubving, take a sample of the water, and look at it. Should be able to tell mineral formation (the result of corrosion) from biological growth pretty easily.

re: denatured alcohol and mountain dew

The chemistry undergrads all snag HPLC grade ethanol. Can't put MeOH in that

Check the labels of course hehe.

pHaestus · 07-14-2002, 12:03 PM

Oops forgot about Zinc and galvanic corrosion. Yes Zinc is reactive. In marine environments people add Zn rods to stop other metals of concern from reacting. Basically the Zn oxidizes more readily than the other metals and so their expensive bits are replaced as long as they add more Zn rods on occasion.

The basic reaction of corrosion is as follows:

Me(0) (solid) -> xe- + Me x+(aq)

Where a metal is oxidized and released from solid to solution. However, most metals are relatively insoluble, so the following reaction also occurs:

Me(x+)aq + xOH ->Me(OH)x (solid)

This is the precipitate that you end up seeing as "crap in the lines".

Since the above oxidation is only a half reaction, there must be some other half reaction that participates. That is indeed the case when dissimilar metals are used. This reaction is fastest when the metals are actually touching, but it can also proceed in an electrolytic medium (for example water in your loop).

I personally use the poly Ts and barbs in my systems for the most part, but because they are cheaper not due to any superiority. Avoid steel (except stainless) and Zn coated stuff and you should be fine.

07-13-2002, 09:56 AM	#26
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	Thanks Nemaste, that was very usefull! creature: You're moslty right. All forms of tubing eventually dry up, and/or decompose, but that usually take a long time, unless it's accelerated by thermal cycling, and chemicals. In your particular case, you are experiencing galvanic corrosion, which is partly delayed by the use of water wetter, but still there nevertheless. Since tubing has a porous surface (microscopically), it will very easily pick up that oxide, and change the color of your tubing. As for your T's, you should give some serious thought to replacing them with PVC types, or at least the brass ones, without the coating. Your coating here is probably what is causing most of your corrosion, as your CPU and RAD are mostly OK together. Silicone is better because it's relatively inert, but worse because it allows coolants to evaporate, right through the silicone walls (hence the discoloration of silicone tubing, with water wetter, and an unexplained loss of coolant). Tygon is a chemically neutral variant of vinyl tubing, but like all vinyl tubing, is heavier than silicone, so not so much a good fit for an RC airplane (a hobby of mine as well). __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

07-14-2002, 10:00 AM	#30
bigben2k Responsible for 2% of all the posts here. Join Date: May 2002 Location: Texas, U.S.A. Posts: 8,302	Prettu much anywhere: plumbing/hardware store, maybe even a pet store. Sorry that you got jipped there, it seems to me like the guy who sold you those things was just out to make a buck, and saw someone (you) that was willing to throw some money at the problem. __________________ WBTA (Water Block Testing Alliance) Nordic Hardware WC 101

07-13-2002, 01:12 PM	#27
gmat Thermophile Join Date: Mar 2001 Location: France Posts: 1,221	Nemaste silicone will lose coolant through its walls because it's microporous. And it's not chemically inert... But like bb2k said it has other advantages.

07-14-2002, 07:39 AM	#29
kibbler Cooling Savant Join Date: Jan 2002 Posts: 107	I usually go to mcmasters.com. Since you're in Norway, that might not be the most convenient. Any thorough enough hardware/plumbing store should have them in at least several diameters

07-14-2002, 11:50 AM	#31
pHaestus Big Player Making Big Money Join Date: Aug 2001 Location: irc.lostgeek.com #procooling.com Posts: 4,782	At the concentrations of water wetter we work with, I seriously doubt that it is damaging to tubes. The pink dye that Redline adds will be absorbed by silicone, but the surfactant (and the slightly alkaline pH) should remain in the water and do its job of lowering surface tension and (somewhat) inhibiting corrosion. Vinyl hose would be at a greater risk IMO because I don't think it is particularly resistant to basic pH. However, this would only be a problem if you poured the water wetter into a fill line as a concentrated solution. Dilute it before adding it to the loop and I don't see why it would be a big problem. Have access to a microscope in a biology lab? Would be interesting to just cut open the tubving, take a sample of the water, and look at it. Should be able to tell mineral formation (the result of corrosion) from biological growth pretty easily. re: denatured alcohol and mountain dew The chemistry undergrads all snag HPLC grade ethanol. Can't put MeOH in that Check the labels of course hehe.

07-14-2002, 12:03 PM	#32
pHaestus Big Player Making Big Money Join Date: Aug 2001 Location: irc.lostgeek.com #procooling.com Posts: 4,782	Oops forgot about Zinc and galvanic corrosion. Yes Zinc is reactive. In marine environments people add Zn rods to stop other metals of concern from reacting. Basically the Zn oxidizes more readily than the other metals and so their expensive bits are replaced as long as they add more Zn rods on occasion. The basic reaction of corrosion is as follows: Me(0) (solid) -> xe- + Me x+(aq) Where a metal is oxidized and released from solid to solution. However, most metals are relatively insoluble, so the following reaction also occurs: Me(x+)aq + xOH ->Me(OH)x (solid) This is the precipitate that you end up seeing as "crap in the lines". Since the above oxidation is only a half reaction, there must be some other half reaction that participates. That is indeed the case when dissimilar metals are used. This reaction is fastest when the metals are actually touching, but it can also proceed in an electrolytic medium (for example water in your loop). I personally use the poly Ts and barbs in my systems for the most part, but because they are cheaper not due to any superiority. Avoid steel (except stainless) and Zn coated stuff and you should be fine.

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