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 Post subject: Inert gas leakage... what's the truth?
PostPosted: Thu Mar 09, 2006 11:05 pm 

Joined: Fri Jan 20, 2006 3:57 pm
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This is a good question for our fenestration experts here to answer- it's something I've often been curious about.

You hear people toss wild claims around, it starts out as a rumour, then it's a problem that a few people start discussing, then as more people hear about the problem it becomes a full-blown conspiracy and you get all sorts of misinformation being spread. So I'd like to hear what the facts are.

From what I've read (that sounded somewhat credible) it sounds to me like there is no way to tell how much inert gas will be displaced from an IGU because it depends on so many factors, and because there is a lack of testing and regulating at this point in time. True?

I've also heard that the percentage of displacement is very small- a fraction of the overall volume of gas is displaced annually- perhaps as small as 1% per year? True?

The reason I ask is because you hear some people make wild assertions like: "there's no sense paying for Argon because it will just offgas and be gone in 10 years anyway." or... "it's just a bunch of hype getting you to pay extra for something that won't be doing you any good once it's gone."

Obviously the gas fill would be gone in the event of a seal failure, but provided the IGU does not fail, what kind of life expectancy does inert gas have?


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 Post subject: A related question . . .
PostPosted: Thu Mar 09, 2006 11:30 pm 

Joined: Sun Feb 12, 2006 3:21 pm
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Great issue XS! Here's a related issue that would be nice to get some facts on or comments from the few true glass experts that frequent this site. (Tackle Xsleeper's question first, he was in line before me)

As argon leaks out, air does NOT leak in to take its place. This will create a vacuum effect in the IG that puts stress on the seal, stress on the glass, and can "hourglass" the panes toward each other. This can cause center-of-glass condensation rather than edge of glass condensation because the airspace could be reduced to little or even none. I've seen it happen numerous times.

I've read on either this or one of the similar forums some info that conflicts with this. What I read (can't remember where or when) from some is that as the argon leaks out, air leaks in. All of my info indicates this is not the case. I would have challenged the allegedly erroneous messages but they were older posts so I didn't bother.


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 Post subject:
PostPosted: Fri Mar 10, 2006 12:21 am 

Joined: Fri Jan 20, 2006 3:57 pm
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I may have read the same thing, Tru_blu. Something about how the Argon/Krypton is atomically small enough to leak out, but the air molecules are not? Not sure how that would work, because anyone who paid attention in science class knows that Argon's atomic number is 18, Krypton's is 36, while O2 would be 8+8 or 16? I don't recall what nitrogen's natural state is.


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 Post subject: Reply
PostPosted: Fri Mar 10, 2006 9:31 am 

Joined: Fri Mar 11, 2005 3:43 pm
Posts: 353
Location: Illinois
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"As argon leaks out, air does NOT leak in to take its place."

Although this is true at the beginning stages of some seal failures, it is usually not the case over time. For the gas to dissipate it must have a path through or around the seal. The added pressure of the vacuum does indeed put additional stress on the seals as well. In most cases, as the seal degrades further the I.G.'s internal negative pressure will equalize itself by drawing in ambient air the first chance it gets. In the cases where this doesn't occur I would presume that the seals are in tact but somewhat selectively permeable.


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 Post subject:
PostPosted: Sat Mar 11, 2006 2:26 pm 

Joined: Tue Dec 13, 2005 8:57 pm
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Polyisobutylene, or PIB, is the only butyl that is impermeable to gas - including argon and krypton. PIB is also the primary ingredient in the TPS spacer system, comprising about 85% of the total volume of material (if memory serves).

PIB is also the primary ingredient in swiggle...well, you know :roll:

Back in the dim and distant past of IG history, IG's were manufactured using various materials to affect a seal between the glass and the (generally) aluminum spacer. Among those materials were polysulfides, hot-melt butyl's, assorted organics, and even silicones. What was consistent about those products was that none of them were (or are, despite the fact that many companies still use them) impermeable to gas passing directly thru them. Not seal failure, simply they were not “gas-tightâ€


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 Post subject: Reply
PostPosted: Sat Mar 11, 2006 3:40 pm 

Joined: Fri Mar 11, 2005 3:43 pm
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Location: Illinois
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As usual, I agree and disagree... lol... but I always enjoy your posts Oberon. You stated, "Not seal failure, simply they were not “gas-tightâ€


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 Post subject:
PostPosted: Sat Mar 11, 2006 8:09 pm 

Joined: Tue Jan 17, 2006 2:25 am
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I'm sure most of you industry pros know this already, but in case it is interesting reading for anyone, there is a Finnish company called Sparklike selling an (expensive) argon fill level testing device. Here is some info:
http://www.sparklike.com/Pages/products/gasglass1002.htm

They claim fairly high accuracy for fill percentage measurements. One window salesman I talked to said their regional office had one of these devices available, and the manufacturer also used such a device on some sample of the outgoing windows to verify initial fill quality.


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 Post subject: Reply
PostPosted: Sun Mar 12, 2006 10:08 am 

Joined: Fri Mar 11, 2005 3:43 pm
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Location: Illinois
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Yes I am familiar with the gasglass tester, I almost bought one. They run about $10,000 and there are only about 100 in use in the US. The reason I decided to wait is that they are in the process of having their results deemed accurate and acceptable by the industry. Until this happens, many that score poorly will simply dispute the readings. The other problem with the unit is that it can only read gas percentage accurately if it's around 80% or more. Below that, it's accuracy decreases considerably. Since a window manufacturer only needs to fill an IG to 67% to call it "gas filled" (and many do this), this creates alot of debates for it's acceptance in the industry.


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 Post subject: Re: Reply
PostPosted: Sun Mar 12, 2006 11:32 am 

Joined: Tue Jan 17, 2006 2:25 am
Posts: 155
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A 67% requirement is sad, especially if the manufacturers can pick and choose which specific sample they send off to be NFRC certified. If there was consistency in the manufacturing after NFRC testing, customers could at least look at the u-value for the the overall window performance with whatever fill it generally gets, but I'm not sure if consistency can be assumed either.

I'm constantly surprised how many 100% X foods have less than 100% of X in it. In one case I saw, the X wasn't even the first listed ingredient, because water apparently does not "count" as an ingredient. But juice is a $2 investment and Windows are a little different.


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 Post subject:
PostPosted: Sun Mar 12, 2006 5:49 pm 

Joined: Tue Dec 13, 2005 8:57 pm
Posts: 113
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:lol:

Okay Fen, I agree that you are technically correct that by definition if the seal fails to keep stuff in as well as it may keep stuff out, then the seal has failed to do its job...and btw, I enjoy your posts as well - even if we are not always in 100% agreement! :P

I have decided to change the term "seal failure" to "seal rupture" when discussing an actual breach in the seal that would allow air and moisture into the IG space...(actually I kinda like that term - "seal rupture"... But I do wonder if that is also a Veterinary medical term?)

And I also agree that a seal rupture that allows air and moisture into the unit is much more common than an imploding IG. Actually an imploding IG is a rare occurance (which is certainly a good thing!) and it tends to be very specific to glass aspect ration, size, thickness, and environment, but if you ever have talked with someone who has had it happen to them...it is quite an event! :shock:

However, on the flip side, it was not uncommon a few years back to see IG's that were manufactured prior to the advent of dual seals and PIB-based seal systems having issues with glass "bowing" because of the argon loss - without corresponding air replacement. The only reason it wasn't even a more well known or discussed phenomenon was because relatively few IG's of the time included an argon infill. It is actually quite possible for an IG unit to lose the gas infill and yet the seal to remain intact from rupture despite the stresses involved - of course window performance would suffer both from an aesthetic and from an energy perfomance standpoint in that circumstance. And it was also quite possible that the stress could cause a seal rupture as well.

Ultimately it was a definite learning experience for the window and IG manufacturers...and it cost them a few dollars in replacement units and repairs.


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 Post subject:
PostPosted: Sun Mar 12, 2006 6:37 pm 
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Joined: Fri Mar 11, 2005 3:58 pm
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Location: Northern & Central Illinois, Chicago suburbs
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Oberon wrote:
I have decided to change the term "seal failure" to "seal rupture" when discussing an actual breach in the seal that would allow air and moisture into the IG space.


I'm not sure but I think I had a "window rupture" once back in the mid 1980's.

I was putting a picture window in one summer morning. The elderly woman was sitting right in front of the TV watching "The Price is Right with Bob Barker". I was doing an outside installation so I moved the TV about a foot away from the wall but left it right in front of the window.
When I set the picture window up into the window opening, I didn't realize it was 2" too short and 2" too narrow. It crashed perfectly right over the top of the console TV and the frame landed on the floor circling the TV. Oberon, would that qualify as a seal rupture??

I felt really bad. The lady sat motionless in her chair and her eyes looked liked this for an hour :shock:


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 Post subject: LOL
PostPosted: Sun Mar 12, 2006 10:02 pm 

Joined: Sun Feb 12, 2006 3:21 pm
Posts: 72
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Speaking of the price is right, our guys went to install a bay window and 2 other windows in a home in the front elevation. Nobody was home, so they proceeded to remove the picture window and 2 double hungs and put the nice new replacements in. Unfortunately, it was not the correct house; the correct one was actually located farther down the street and looked the same. But the price was right, and the owners of the home that never ordered windows were thrilled with their free new windows. :oops:


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