Argon filled double glazing.

[harryagain]

I wonder how long the argon stays in these gas filled double glazing units. (I wonder why they don't use CO2.) No way of telling if/when it's all leaked out. Waste of money if you ask me.

[Brian Gaff]

Well probably the greenies won't let them use Co2?

If its argon, surprised they don't put electoodes in each side and turn it into some kind of light!

I am joking.. Brian

[Davey]

Sounds like a good idea........

[PeterC]

They should be filled with a vacuum - that won't leak out.

[Nightjar]

Some are.

Colin Bignell

[GB]

It would effectively turn it into single glazing, though, except around teh edges.

[Tim Downie]

You often see concave DG units but I've been told that that is due to poor manufacturing technique rather than deliberate policy. It happens when a window unit is sealed whilst it is laying flat rather than on edge.

Tim

[The Natural Philosopher]

eh?

[The Natural Philosopher]

bullshit

[Tim Downie]

Why do you think that? I was told it by a DG installer. Makes perfect sense to me that if a large window is laid flat, the top pane will sag under its own weight. If the unit is sealed in that position, you end you with a permenantly concave unit (which looks a bit crap in my opinion). Sealing the units whilst upright prevents this happening.

Tim

[Dave Plowman (News)]

Hmm. Gravity versus air pressure. Discuss. ;-)

[dennis]

Glass doesn't bow much under its own weight in the typical sizes used for glazing. Its more likely that they made it on a hot day and the temperature and pressure dropped after they sealed it.

[dennis]

A vacuum doesn't conduct heat, glass does so its not the same.

[The Natural Philosopher]

QED

Makes perfect

Google youngs elastic modulus

[GB]

Vacuum inside. 14 psi (in old money) pressure on the panes from the atmosphere. The panes will bend inwards until they touch in the middle. The edges are kept aupported at the sides by the spacers, assuming that these are strong enough not to be crushed by the very considerable force on them. Come on guys, think back to O level physics.

[Robin]

Pilkington telling porkies?

includes

"Pilkington Spacia is the world's first commercially available vacuum glazing. It offers the thermal performance of conventional double glazing in the same thickness as single glass (6 mm). "

[PeterC]

Probably only for small(ish) units. Rather worryingly, under "How it works", it mentions that conventional units have a gas-filled gap of up to 20mm so the o/a thickness is 24mm - rather thin glass methinks.

[PeterC]

Not if it's a special HP vacuum it won't.

[Robin]

AIUI the reverse is true: there is a *minimum*size (200x350mm). Max. is

1500 × 2500 for the really thin stuff. So in typical cases of old buildings it is fitted as laregish panes (by old standards) and dummy bars applied. With bigger spacing they can go up to nearly 2800x6000.

I've also read that the spacers are not fixed to the glass but are held in place by the pressure on each pane. So if the vacuum fails the dots fall down and you can see that in order to maintain your stately pile you need to sell another serving wench, son, kidney etc......... (Fortunately for me I was sitting down when I asked about price some time ago.).

[Fredxx]

Are you suggesting that there are different grades of vacuums? Where a common or garden vacuum will allow the atmosphere to exert nominally 1 bar on the pane, but a "special HP" one won't??

Do you have any qualifications in physics?