Water Pressure - Laws and Calculator

[Rivermud]

The hardest part about acrylic is that there are sooo many ways to make an acrylic tank. They are constructed completely differently. They also have a lot more elasticity, meaning they will flex a whole lot more than glass. Glass doesn't flex much before it breaks. I'm sure someone knows more about acrylic than I do.. maybe they have a more definitive answer..

As for the calculator provided on the other website... it was not built properly. I went through and created a new one using google docs, it works very well. Please do not use the calculator from the other site. If any of you would
like a copy of the one I wrote, just let me know.

 

[Jgray152]

Random Post, but ok.

There is a calculator that takes saftey factors into consideration.....

http://www.innovationlandscaping.com/pictures/GlassThicknessCE.xls

 

[72cutlass]

If were gonna split hairs over guppies hitting the wall 62.5 is not the proper weight. A unit weight of 62.25 would be more appropriate as that is water at 75° F. Also you are assuming freshwater, saltwater and brackish water keepers need to take there specific gravity and multiply that times the 62.25#. For instances the proper Weight for 1cubic foot of seawater (1.028) would be 62.25x1.028 yeilding 63.8. Not a tremendous difference but i think if you are going to explain this stuff, using the proper #s would be beneficial.

 

[72cutlass]

oh and ive been signed up here and lurking for a long time lol, just decided to chime in on this for the hell of it. Got my fluid mechanics exam tomorrow.

 

[Rivermud]

Random Post, but ok.

There is a calculator that takes saftey factors into consideration.....

http://www.innovationlandscaping.com/pictures/GlassThicknessCE.xls

That calculator is broken. Look at the bottom calculations. That is the exact same calulator as the one I linked with a few decorations added. I went through and fixed the formulas and have a working copy if people are interested.

 

[Rivermud]

If were gonna split hairs over guppies hitting the wall 62.5 is not the proper weight. A unit weight of 62.25 would be more appropriate as that is water at 75° F. Also you are assuming freshwater, saltwater and brackish water keepers need to take there specific gravity and multiply that times the 62.25#. For instances the proper Weight for 1cubic foot of seawater (1.028) would be 62.25x1.028 yeilding 63.8. Not a tremendous difference but i think if you are going to explain this stuff, using the proper #s would be beneficial.

Well, seeing as the vast majority of DIY'ers on this site are not brackish nor saltwater it had not occurred to me to further complicate it by adding extra numbers. From feedback I've seen so fr most people either just want to find something to argue about or really don't care. It would not bother me in the least to have the moderators completely remove this thread and continue to use the glass thickness sticky. People will continue to argue over glass thickness and anything else they possibly can.

Also your point assumes a pure water environment. The post was merely there to illustrate the properties of glass, the safety factor rating and the mechanics behind how they come up with the numbers and why. I went through and even built a new calculator with a google spreadsheet because the original calculator was wrong so that people who were not interested in the mechanics could simply plug numbers and be happy.

Either way, If a mod would just simply remove this thread it won't break my heart. It is not providing any benefit and I don't feel the need to stand behind it.

 

[yogurt_21]

the funny thing about this and the glass thickness thread is that they assume you're bulding an all glass tank. And if you have a scan down the diy section those are so few and far between that they hardley apply.

most on here are doing plywood builds. in which case they'd only need the thickness requered for the front and possibly side panels.

 

[Rivermud]

the funny thing about this and the glass thickness thread is that they assume you're bulding an all glass tank. And if you have a scan down the diy section those are so few and far between that they hardley apply.

most on here are doing plywood builds. in which case they'd only need the thickness requered for the front and possibly side panels.

I think you need to re-read the post
"Thus for aquariums we build that are NOT all glass AND are framed (ie braced with wood) the safety factor CAN be reduced. For enclosures that are all glass or not framed, the following should help clear up the mystery behind the safety factor calculations."
My original point in posting the information found in the top half of the original post.

The rest of the post is a detailed formula for calculating glass thickness based on safety factor. The safety factor can be reduced like I stated previously.

It's like pushing on a door that says "Pull" I swear.

 

[apisto]

@Rivermud,

I'm not one to spilt hairs. Thanks for making the effort and I do agree with what you say. Let's not go into temperature and other variants that have a very minor effect if any at all that is of any practical consequence. One reason safety factors are build into the equation

Please put up your calculator and we can have a look. I have been building tanks for twenty odd years and I tend to over build. Would be interesting to see how badly.

Thanks in advance

 

[Rivermud]

Here you go. Rivermud's Glass Thickness Calculator

If people decide it's useful I will make it into an html or downloadable sheet. Be patient, it may take awhile to load as it is making an excel doc public. Be sure to read the instructions before editing the fields. Please change only the Length, Height, Width, and Safety Factor fields. If you accidentally change the other fields, simply close the page and reload it from the link above. The calculator is designed to show an unsupported all glass tank. If you are building a supported framed enclosure like most of us do then you can change the safety factor rating as you see fit. If this is the case, disregard the bottom thickness as it has no bearing on your calculations.