i need help with a safe air tank thickness to psi ratio for metals

[Ben88012]

so i was compressing a small air tank i made for my homemade air powered car and it ruptured at around 5000 psi

lucky me that I put it in my small very thick steel "blast box" that directed the air away from me.

before I proceed to higher pressures, I need a ratio of thickness to pressure for metals and different things like carbon fiber for safety. also how many joules of energy are in one gallon container of air at 10000-20000 psi at room temp. I need to know for how many miles I can get out of my car

I have lots of safety tests to do before I build it

Edited May 24, 2017 by Ben88012

[John Cuthber]

You need to learn to "proof test" tanks with water first.

Then you need to learn that this idea

"

tank thickness to psi ratio

"

won't work.

Edited May 25, 2017 by John Cuthber

[Manticore]

Shape is also critical - spherical will always be strongest.

[Ben88012]

thanks for the tips

maybe they will prevent me from having to rebuild my wall...

again yay for having modular walls

[John Cuthber]

If you are looking for a ratio the simplistic one for a cylinder is something like the ratio of the diameter of the vessel to the wall thickness must not exceed twice the ratio of the tensile strength to the pressure.

 

https://en.wikipedia.org/wiki/Cylinder_stress

 

But, no matter how clever the design is, make sure you proof test it with water, not gas.

[MigL]

You may have modular walls...

But not body parts !!!

[Manticore]

Pressure testing the De Havilland Comet - from: http://www.tech.plym.ac.uk/sme/Interactive_Resources/tutorials/FailureCases/sf2.html

 

"Water was used for this pressurisation because calculations had indicated that the energy release under cabin rupture with air as the pressurisation medium was equivalent to the explosion of a 500 lbf bomb in the cabin."

[Externet]

Ben88012 : Can you please let me know what equipment did you use to compress air to 5000 psi and can/plan to reach 10000 - 20000 psi ?

[Ben88012]

i was planning on putting the pumps in a staged pressure chamber series to increase pressure

for example: if I were to put a 5000 psi pump in a 5000 psi tank that is pressurized I can theoretically get 10000 psi out of it as long as I take the air from the inside of the tank

for compressors I first used a pcp air gun hand pump

then I used a scuba pump inside of a tank to further pressurize

of course it will also work with a scuba pump initiation

Edited May 27, 2017 by Ben88012

[John Cuthber]

How do you plan to feed power into a 5000 PSI tank?

[Ben88012]

I was going to use induction will it work

[John Cuthber]

I was going to use induction will it work

Not through metal.

[Ben88012]

special ceramic perhapse???

Edited May 27, 2017 by Ben88012

[John Cuthber]

There comes a point where you should give up.

[Ben88012]

good point

well perhapse i just meed to rethink my compressor setup

[John Cuthber]

You need to rethink the whole project.

[Ben88012]

deal

[Externet]

A very serious hydraulic pump may reach those serious pressures.

If there is air above the surface of the hydraulic fluid, you may reach those serious air pressures by using a hydraulic pump.

If the proper fluid does not self-ignite !

A serious container of guessing 3 inches wall perhaps can contain 20000psi

Scuba air compressors will not go beyond 4500psi. Scuba tanks are for 3000psi and their wall is around 0.5" at most.

 

Do your calculations on the volume of air that the car motor needs per revolution; the volume of air before compressing that fitted in the reservoir, and you will know how many blocks can run.