AL80 compression

[jimmyboy]

Does anyone know at what depth a AL80 would start to compress, just curious.

 

[hdtran]

Does anyone know at what depth a AL80 would start to compress, just curious.

Strictly speaking, at any depth, an AL80 tank will compress. When pressurized, it will expand a tiny bit. That's the principle behind wireless pressure transducers; they have an electronic device which measures the very small deformation of a diaphragm under pressure (3000 psi), and as that deformation reduces, your pressure in your tank reduces.

I'm not quite sure what your question is. Perhaps you were asking at what depth an AL80 tank would collapse and be crushed?

 

[Rick Murchison]

Does anyone know at what depth a AL80 would start to compress, just curious.

Ahem... if you're asking at what depth a full (3000 psi) AL 80 would start taking on water instead of releasing gas when the valve is opened, that's about 6600 FSW.
If you're asking how deep the crush depth is with an empty cylinder and a closed valve, I have no idea but I'll bet it's very deep.
What are you asking, by the way?
Rick

 

[jimmyboy]

full cylinder, crush depth

 

[H2Andy]

for the Permit class subs, crush depth was around 1900 feet:

http://www.fas.org/man/dod-101/sys/ship/ssn-594.htm

so i would guess less for a tank, since the aluminum is not going to be
as strong as the steel the subs are made from?

just a guess...

 

[jbd]

full cylinder, crush depth

In that case it would be much deeper than the 6600 FSW mentioned by Rick above. You would have to overcome the structural intergrity of the tank when empty at sea level as well as the 3,000 psi which would be supporting the tank.

 

[jbd]

for the Permit class subs, crush depth was around 1900 feet:

http://www.fas.org/man/dod-101/sys/ship/ssn-594.htm

so i would guess less for a tank, since the aluminum is not going to be
as strong as the steel the subs are made from?

just a guess...

The sub only has an internal pressure of one or maybe two atmospheres.

 

[Rick Murchison]

Without trying to figure out why you'd want to know... the general shape of the cylinder is extremely robust as far as crushing is concerned (ever try to crush a raw egg with your bare hand?). Since the pressure in a full cylinder would only equalize at 6600', I'd put money on one making it to at least double that, if not all the way to the bottom of the Mariana's trench.
As for the comparison with a sub... the sub isn't a high pressure gas cylinder and isn't anywhere near as strong as one.
Rick

 

[H2Andy]

The sub only has an internal pressure of one or maybe two atmospheres.

ah, yes of course...

they don't pump air at 3000 psi inside a sub

and a question:

wouldn't the walls of a sub be thicker and stronger than those of an empty AL tank?

 

[hdtran]

Failure mode will likely be compressive buckling, not yield. I'd have to charge a consulting fee to run an analysis