Laminated glass - Tempered with non-tempered

[bymoor]

I'm planning to start 800 gallon(3000 liters) plywood tank project, but I'm having problems finding thick enough glass for it here in Finland. Calculations shows that 3000x800mm window will need 19mm glass. I've studied a bit about laminated glass and it revealed that 10+10mm laminate ain't so tough as 20mm glass. The thing is that I can get 10mm glass really cheap, but price will go up rapidly if going to thicker gauges. And I'm not so keen to take fully tempered and laminated glass, because it might shatter suddenly flooding my apartment instantly.

Now for the question.. Is it ok to make laminated glass by laminating 10mm tempered glass with 10mm non-tempered glass? I was going to put that tempered glass towards outside. This way that constant tension would harm laminate sheet less(I've heard that it's possible that laminated layers may tear apart in long run, because outer glass needs to bend/stretch more than the inner one.) and getting scratches inside the tank wouldn't be so harmful for it.

I know I'm a bit too careful with this, but I really don't want to make mistakes with it.

Oh.. And couple of pics for the plans:

 

[Knowdafish]

1) How would you laminate it?

2) I would find out if the 2 are compatible besides on MFK
(Would they expand/contract at the same rate with temperature?)
If one fails/breaks I'm sure the other would fail too!

3) Why not acrylic? Is it available there?

I would bite the bullet and spend what it takes to do it properly and safely considering the consequences if it fails!

 

[bymoor]

1) How would you laminate it?

I'm gonna order it as laminated from one company.

2) I would find out if the 2 are compatible besides on MFK
(Would they expand/contract at the same rate with temperature?)
If one fails/breaks I'm sure the other would fail too!

Well that was the main question pretty much.. So is it ok in general to laminate different glasses together?

3) Why not acrylic? Is it available there?

It scratches easily. for some reason no one uses acrylics in Finland.

I would bite the bullet and spend what it takes to do it properly and safely considering the consequences if it fails!

I've seen 80cm high tank made of 10mm glass. Also one supplier calculated that 15mm or 8+8 tempered+laminated is enough for that window. So I should be on safe grounds here.

The reason I would like to use non-tempered glass there is that if it breaks for some reason, that non-tempered glass along PVB sheet will hold it together for that time that water may trip into backup tank, which I'm going to build under this.

 

[dawnmarie]

I will be surprised if you find the answers you are looking for on this forum . Glass lamination is not a DIY undertaking. If you have already found a company to do the work it would seem like they would be the best equipped to engineer the solution and warrantee the end product.
When you do solve this please come back and share the results.

 

[The1and only]

I actually asked this question of a glass supplier when the Bank vault below my work was swapping out all the bullet proof glass for bullet proof lexan. They were throwing away the old 2-1/2" glass in 4x8 sheets. It was 5 layers laminated together. The installer was an aquarium guy as well and he said it is only as strong as the thickest piece of glass. I thought that was BS so I did some more research and it is true. Laminating the glass adds some strength but not enough to have an engineer raise the safety factor above that of the thickest piece. It has something to do with the way the laminates are bonded together. It is not like when you screw two boards together. So in the end the super thick bullet proof glass went in the trash because it could not be cut down (I guess some layers are tempered) and would only safely support a 24" tall tank. Now I am not an engineer I am just going off what I was told by the installer and an engineer that I used to know.

 

[bymoor]

The installer was an aquarium guy as well and he said it is only as strong as the thickest piece of glass.

Yep I noticed this too from some strength measurements done by finnish VTT. 10mm tempered glass will give enough strength itself and that another 10mm float glass is just a backup. But if both glasses are tempered, the laminate could break instantly like this: http://upload.wikimedia.org/wikipedia/commons/4/4c/Broken_Laminated_glass.JPG
"Tempered laminated glass is designed to shatter into small pieces, preventing possible injury. When both pieces of glass are broken it produces a "wet blanket" effect and it will fall out of its opening."


When another glass is thick enough float glass, it should hold it's form better. Something like this wanted:
http://www.youtube.com/watch?v=qbIZjJ-7yYQ

So in the end the super thick bullet proof glass went in the trash because it could not be cut down (I guess some layers are tempered) and would only safely support a 24" tall tank. Now I am not an engineer I am just going off what I was told by the installer and an engineer that I used to know.

Here it is again. So is it ok to mix tempered and non-tempered glass in same laminate?


EDIT: So all this speculation about glass breaking up is just me preparing for the worst. This is how I design everything in my life. Every part of the design can fail no matter how precisely you plan and do it.