They will leak out that way but only incredibly slowly ( 100 years ) Through gaps and poor workmanship faster but this is rare

It will be easy to tell if this is happening as air will have to enter and with it water vapour so the units will fog up and they dont so no leaking and it was nonsense

Hmmm.... I suspect the truth may lie somewhere between the factory gate and 100 years. I would be interested in an authoritative view.

>a quite different timescale from gross seal failure

Longer or shorter?

Posted By: biffvernon>a quite different timescale from gross seal failure

Longer or shorter?

Either - it's a different process - actual seal failure leading to gross leakage, versus diffusion (different rate for different gases).

Not so much shocking that we do not know the answer now. If I was a sceptic I would suggest it is a barefaced lie that no one has either asked the question looked into this and come up with a very uncomfortable answer.

How many would they sell if they said: " well, it works brilliantly under experimental conditions. We can also say, with abolute confidence, that it works for AT LEAST a few seconds after it has been filled with gas. After that you might as well have stuck with you're '80's Anglians and fitted thick curtains."

I smell a pile of serially digested grass remains deposited by a male bovine in these 'ere inert gases!

Do they not come with some sort of guarentee on contents of the filing (like jammy dodgers).

S.

And here:

www.byv.kth.se/avd/byte/reykjavik/pdf/art_155.pdf

A quote from the summary

"So far, inspections show that the gas concentration in sealed glazing units is a little bit too low in most of the inspected windows, measured values are between 75 and 90 %. Gas filling in sealed glazing units decreases the U-value by about 0.1-0.2 W/m2K, which means that, if the gas concentration falls by 10 %, the U-value increases by 0.01-0.02 W/m2K. In new windows, the average gas concentration should be about 90 %."

Actually not THAT bad - but not great either.

There is little data in the stuff I found but interestingly both give similar figures. Samples appear small to me given the large number of these units out there and most work has been done on test units rather than those actualy fitted in windows in houses/buildings so pick up a nice big handfull of salt. It would be much better if there were more references based on real windows - one is left to wonder why there are not more such studies (or more recent ones turning up on the first couple of pages in a google search) given the realtive ease of testing in a non destructive manner.

Both links above cite about a roughly 50:50 chance of (as far as I can tell) factory supplied test units having more than 90% argon in them (the suggest lower limit ranges in both with 90% accepted in one and 90% described as too low in the other. They also report a 1 in 10 chance of having less than 70% argon (from the same sample). The only 'field tests' cited show concentration ranges of 75-90% but this in not further analised.

It appears that there is an acceptance of loss of Argon at a rate of up to 1% per year in the best sealed units (under test conditions). Another stat' is that 50% and above Argon concentration has a measurable affect on U value (unfortunalely we can't see the table referred to). Each 10% Argon is apparently 'worth' 0.01-0.02 W/m2K with Argon fill described as decreasing U value by between 0.1 - 0.2 W/m2K (not sure I believe it is a straight line - anyone care to comment).

Any way you look at it neither is telling a very good story considering all the extra faff and cost as far as I can see.

S.

Nah

Most common noble (inert = reacts with almost nothing), colourless, odourless, non toxic, gas found in the atmosphere (less than 1% I think). So you breath it in and drink it all the time.

Flourine gas is reactive enough to bully it into forming chemical bonds but that is about it.

S.

Isn't the argon produced as a waste product from natural gas production, rather than coming from air?

Ah, well krypton and xenon are not common gasses like argon, so I guess that's not surprising.

Posted By: biffvernonIsn't the argon produced as a waste product from natural gas production, rather than coming from air?

No, that's helium - and there's going to be a shortage due to the general decline in natural gas production. But that's a whole other story.

Paul in Montreal.

Gas leakage from double glazed, double sealed, units varries with sealant type. Using old 1990ish technology: -

Polysulfide 5% to 6%
Polyurethane 2% to 5%
Silicone 12% to 15%

Reported as I understand it in:
Arasteh, D., Selkowitz, S., Wolfe, J.R., "The Design and Testing of a Highly Insulating Glazing System for Use With Conventional Window Systems," Journal of Solar Engineering, Transactions of the ASME, 1989, vol. 111.
Thikol Gesellschaft mbH, "Gas Permeability of IG-Sealants," Morton Thikol, Woodstock, Illinois, 1988

Leakage rates should have reduced with new spacer technology due to reduced thermal stress etc. But I have no data on this.

Mark

Sorry, meant to say, 20 years.

Mark

No more gas fields = it can be distilled from air. Also the reason that it is in natural gas is because if forms underground it could even be that there are helium pockets trapped in various places underground waiting to be discovered. New business opportunity? Helium prospecting.

Why not?