Glass strength and double laminate

[leslie hempel]

interesting read!

also, If I'm not mistaken, "true" bullet proof glass has thin layers of poly carb in the lamination?

i cant remebber the composition but i do remember thet there are 3 strengthe from taking a bullet from a revolver to a AK47. 29/54/63mm is what we were able to supply but it was hellish expensive.. one of our glass suppliers has a piece with a bullet shot at it on display in their show room.. awsome stuff

 

[dallasg]

Many thanks to everyone, Hennie, Rob and Nemo J

these are the perfect answers...

Now the next part, how much more expensive is it, anyone know how much 24mm would be per sqm?

thanks

 

[Reef Maniac]

Just to clarify... from my previous post, quoting Pilkington Glass:

Laminated glass is 50% to 100% as strong (depending on aspect ratio and framing details) as monolithic glass of the same overall thickness

This means that laminated glass strength varies from half as strong as normal glass, to the same strength as normal (monolithic) glass of the same total thickness.

I'm not sure of the cost difference between the two types of glass, but if it's approximately the same then I would rather use a monolithic glass of (say) 12mm thickness than a laminate of two pieces of glass of 6mm thickness each (totalling 12mm of laminated thickness). The main reason for this is from the last part of my previous quote: Laminated glass, at room temperature, of the same thickness, will deflect about the same amount for short duration loads (seconds) but will behave as sliding layers and deflect further under long duration loads (hours or days).

Hennie

 

[dallasg]

thanks Hennie,
i was using to glass calc, and needed a base of 24mm, but i am thinking that i will stay with in the boundaries of 12mm

another quick Q, if the tank stand has a solid base, supporting the total surface of the base, would staying at 12mm when a 15mm+ thickness is need be ok?

 

[Reef Maniac]

another quick Q, if the tank stand has a solid base, supporting the total surface of the base, would staying at 12mm when a 15mm+ thickness is need be ok?

Yes, I think so.

If the base is uniformly supported by a stand/slab which has less deflection than the glass, the stand will support the glass, and carry the load transferred by the glass. In such a case, one can safely use thinner glass, IMHO.

Hennie

 

[Nemos Janitor]

Two pic's of the 33000 ltr build a few years ago.

 

[dallasg]

thanks Hennie,

the stand will have a 10mm steel sheet with ply on top, with polystyrene then the tank, its over kill but i thought why not

 

[borgdrone7]

Two 8mm work for years

Hi,

My brother made 1.5mx0.6mx0.6m aquarium from 2 laminated 8mm glass parts. It is working for years now without problems. So these are definitely stronger than one 8mm. Also, pressure from water is not trying to slide the parts so I think that's why "hours, days" prediction is not true. If it was true 8mm aquarium would long time ago break.

 

[Reef Maniac]

Hi,

My brother made 1.5mx0.6mx0.6m aquarium from 2 laminated 8mm glass parts. It is working for years now without problems. So these are definitely stronger than one 8mm. If it was true 8mm aquarium would long time ago break.

Hi borgdrone, and WELCOME to MASA. Hope you have a long and happy association with us

The point is not really about whether one 8mm pans is stronger than 2 x 8mm panes laminated together - obviously the laminate will be stronger. The point is that 1 x 16mm monolithic pane will be just as strong, or even stronger, than 2 x 8mm panes laminated together.

In your brother's case, our Glass Thickness calculator shows that a single 10mm pane will be sufficiently strong, so a 16mm laminate will obviously be sufficient for the job

Also, pressure from water is not trying to slide the parts so I think that's why "hours, days" prediction is not true.

Actually, in a modern marine aquarium there can be quite a large, and varying, "sliding" force (pressure) on the glass, caused by wave makers, surge devises and other pumps creating chaotic water flow.

Hennie

 

[borgdrone7]

It is probably about 80%

Hi,

Thanks for your welcome wishes. As for the sliding force I could not assume it could be so big due to water movement. Also, I talked with him and he said he found scientific document dealing with strength of laminated glass. It was pages and pages about laminated glass and all kinds of test. At the end conclusion was that laminated glass can be approximated to 80% strength of one monolithic glass. So 16mmX0.8=12.8mm which should be more than enough since, as you said, for his aquarium size 10mm is enough.
I am puzzled now because I wanted to use 2X6mm for 1.2mX0.5mx0.5m but after some reading here I am little discouraged. Laminated glass was perfect in my opinion but now I am not 100% sure.

 

[Reef Maniac]

I am puzzled now because I wanted to use 2X6mm for 1.2mX0.5mx0.5m but after some reading here I am little discouraged. Laminated glass was perfect in my opinion but now I am not 100% sure.

If you use the Glass Thickness calculator you will see that with those dimensions (and assuming the water height to be 450mm) you should be quite safe with a single 8mm thickness pane for the sides (not sure if you get that thickness in Bosnia, but here in South Africa it's pretty difficult to get, as our normally available glass thickness jumps from 6mm to 10mm...) If not, then use 10mm glass, which should still be cheaper than 12mm laminated glass.

Hennie

 

[Nemos Janitor]

Guys only use laminated glass where you have to. This is normally for very large tanks where the thickness of the glass exceeds 19mm. The only reason should be an availability issue.
Also the laminate discolours the glass, and in time the viewing pane will become a pain. IMO

 

[borgdrone7]

Bottom glass thicknes.

If you use the Glass Thickness calculator you will see ....
Hennie

I used the calculator but I get very pessimistic thickness for bottom side of aquarium. Does this calculator assumes aquarium will not be on solid stand? Also, can someone explain safety scale in terms of what does for example 3.0 safety factor means in real life? What does 1.9 means, what does 5.0 means?

Thanks

 

[Reef Maniac]

Does this calculator assumes aquarium will not be on solid stand?

Yes.

can someone explain safety scale

The safety factor of 3.8 is what is recommended by the major glass manufacturers for this type of use. One can reduce the safety factor somewhat if the tank is not located in a high-risk area (e.g. where there is no risk of children running around or playing ball...), and/or if the tank is well braced and on a very strong and sturdy stand. How far one can go is open to discussion, though. The colors shown in the calculator gives some "gut-feel" indication: don't even consider going into the red, and only go into the yellow if you are very sure of the conditions influencing your setup (or if you are feeling very lucky...)

Considering the cost of our live stock and other equipment used in our tanks, I would, however, recommend that one should stick to the recommended safety factor. I speak from personal experience when I say that it's no fun when a tank cracks and dumps about 500 litres of salt water into your lounge. My previous tank failed disastrously some 6 years ago, and the total cost to replace carpets, furniture, tank and equipment came to many times the cost of the original tank.

Hennie

 

[Nathan ross]

hey dallas
we built a small tank using 6mm laminate glass, meaning 3mm, laminate and another 3mm glass. Filled up, everything went well for 30 min then the inside glass cracked followed by the outside one. did some research and replaced with single sheet of 6mm glass and it`s been going for a long time now.
hope that might help.

So if had to build a normal 4 foot with a 10mm base and 8mm front and back with bracing all in 8mm can I use normal clear float glass or is it not recommend

 

[Whoknows]

So if had to build a normal 4 foot with a 10mm base and 8mm front and back with bracing all in 8mm can I use normal clear float glass or is it not recommend

You can. It will work just keep the height to 500mm. My 4ft is 6mm front and 10mm base been running 6 years now.

 

[Nathan ross]

You can. It will work just keep the height to 500mm. My 4ft is 6mm front and 10mm base been running 6 years now.

@who knows Please can you message me on WhatsApp I'd like to ask a few more questions about the glass