Working out the Glass saftey Factor for a Ply tank

[waynes world]

Hi all, in the design for my 9 foot x 3 foot x 34 inch high tank, overall size, with a window opening of 100 inch x 30 inch, i was looking at and found 15mm glass, but now i have been looking around this is a overkill on the safety factor, i spoke to a tank manufactuer and he would build the complete tank from from 12mm, but at the cost of £3500 so this got me thinking, will will 12mm be a good SF for the window, i ask as the SF differs from a complete glass tank. It will save me a bit aswell dropping down to 12mm from 15mm. The 15mm will only be £210 though.

all best

wolly

 

[David R]

No way would I go 34" high with 12mm glass, looking at a safety factor only just over 1!!

http://www.theaquatools.com/building-your-aquarium

I'd say you wouldn't want to go much over 600mm high with 12mm glass and that footprint, 15mm glass would certainly be a safer option if you want the height.

 

[Drstrangelove]

Seems too thin. Assuming that the bottom of the window pane is 30 inches below water level (which it may not be, in which case it's even worse), you'll have a deflection of 1.4 and a safety factor of 1.7. Even 15MM is barely above a SF of 2.6. (I'm aware that the bottom 1" will have lots of support. Just considering that the actual 29th inch may be more than 30" below water level.)

I can see a SF of 3.8 at 580MM high however for 12MM, or 675MM height with 15MM. Again, you didn't say how deep the glass, so this is a little optimistic.

Changing the design to 2 panels (50"x34") would work with 15MM glass at 762MM high. They might give you a discount on 2 x 50x34 versus 1 x 100x34, since their setup time is zero on the second piece. I don't know the glass industry, but I'd expect some discount.


Of course, 3.8 is meant as a guide and people do get by on a lower SF. It's possible of course that your design provides more support than the one people use 3.8 SF glass on. I'd get more opinions.

 

[waynes world]

Yes i was shocked when they said they would build it all from 12mm, more when 8x2x2 are built from 10mm over ehre in the UK.

So say i go overall height of the tank is 30 inch, and with a single window opening of 100 inch x 26 inch ( the 675mm ) and 2 inch off the bottom, so its in the middle of the tank, this will be same as you say with the 3.8 SF with 15mm glass.

thanks for the help guys

wayne

 

[Drstrangelove]

That puts you at no less than 3.62, which should be fine, especially if you have cross bracing. (I used 27" for the depth assuming the water level is at the absolute top.) Most times people have at least an inch or two space, which will equal at least 3.8.

I hope you can get more input. I think if you have any significant cross bracing that may give you some extra wiggle room.

I've noticed (in a few posts) that some of the builds outside the US use thinner glass. Obviously they don't expect the tank to fail, but the thinner glass will probably need more bracing to work.


http://www.canreef.com/vbulletin/showthread.php?t=46858

Here's a post on this which you will know but is interesting to me anyway. Maybe the thinner glass will work if you are building it like this?

 

[CJH]

I've noticed (in a few posts) that some of the builds outside the US use thinner glass. Obviously they don't expect the tank to fail, but the thinner glass will probably need more bracing to work.

I don't have much helpful to contribute to this thread but wanted to mention I've noticed the same thing - there are some glass tank builds in the UK that use surprisingly thin glass for their height.

I'm pretty sure they also use laminated safety glass and (I think) tempered glass much more than US companies do.

Waynes World - what type of 12 mm glass was that company going to use? Float? Tempered? Laminated safety?

 

[waynes world]

For bracing i am going euro with 18mm ply laminated and either 1 or 2 cross braces which will be ply and laminated again, should be fine that, famous last words hey...should, lol, i may not need the 15mm glass with all the bracing but its a good night sleep i want aswell.

CJH, not sure what glass actualy but i guess the same as what all tanks are made from, which i thought was Float.

So are we happy with 15mm float glass for this..........its your heads on the block if it busts LOL

 

[Drstrangelove]

I would feel comfortable with that thickness, especially with bracing. The safety margin is designed to accommodate a number of issues and barring really poor glass or physical damage, that works.

 

[Divinehammer]

I agree 15mm glass should be fine for your build, with the euro bracing and center braces, I am building a 240 Gallon plywood and glass tank 8'x2'x2' 3/4" plywood on all 6 sides and 3 windows on the front with a single pane of glass 94"x23", my top is 1 piece with 2 holes cut in it 4" sides and 6" center brace, and 4" front and back. better to over brace then under. and always have a quality control inspector inspect your work LOL!

 

[waynes world]

Divinehammer, can i ask why the 3 windows, is it for the looks, good build mate. Over here i can pick a 8x2x2 up for less than i can the piece of glass for my build lol, but i want bigger