Building a hydrostatic pressure chamber

[AnnaC]

Hello!

I am currently looking into building a small hydrostatic pressure chamber to test the behaviour of a piece of tissue (cartilage) under physiological pressures. The pressure range should be between 5-15 MPa.

I need to measure the volume change/deformation of the tissue, so the chamber would need to be transparent. Ideally I would like to be able to videofilm the process, from a side view. I have an Instron compression machine that I can use to move a piston. However, I am bit uncertain about the design. What transparent material can withstand such high pressures?

Any help or direction to sources of information would be greatly appreciated!

 

[Velikovsky]

Heavy gauge Acrylic/Plexiglass sheet or tubing/piping would likely fulfill your requirements depending on your design.

 

[AlephZero]

Bear in mind that 15 MPa (about 150 atmospheres) is getting into the same pressure range as a scuba diving air tank.

If you still want to design your own pressure chamber (given your level of "uncertainty" about how to do that), make sure you aren't standing anywhere near it the first time you test it!

 

[AnnaC]

Thanks! Yes, I am a bit hesitant over the high pressure and what materials can actually withstand it. And as you so correctly point out I need to do a whole lot more research before the plans will come alive (and I might just end up aborting the mission completely). But figured I might just as well post here see if anyone had any brilliant ideas before I go talk to the work-shop and see what they say.

Thanks for both of yours help though.

 

[AlephZero]

Yes, I am a bit hesitant over the high pressure and what materials can actually withstand it.

The high pressure" in itself is not much of an issue. Almost any material would withstand a stress of 15MPa in direct tension or compression.

The issue is that at some places in the complete structure you will probably have stresses which are much higher than 15MPa, and the stresses will depend very much on the complete design. For example a "rectangular box", with flat panels for easy observation of what is inside, would be much more highly stressed than a cylinder or a sphere. (That's why diving air bottles are not rectangular boxes!)

 

[dlgoff]

The issue is that at some places in the complete structure you will probably have stresses which are much higher than 15MPa, and the stresses will depend very much on the complete design. ... (That's why diving air bottles are not rectangular boxes!)

And where the valve screws in is much thicker. This might be helpful for the OPs design:

https://docs.google.com/viewer?a=v&q=cache:gQRUGIAkX_AJ:faculty.washington.edu/vkumar/me356/pv_rules.pdf+&hl=en&gl=us&pid=bl&srcid=ADGEESh62sRPl53jTbfGItKY3_1ZaTCVBSG015NmYix-tuBacLRg1M1ykUn1qAU0kIHkSq0alnxCWfWK3GPSwOibfaUyCi1e9Syk9mGpu5kfX2Rv5ynfGPAgbWkupgODdPsCsxyggp7X&sig=AHIEtbQFwsGhUffnTx1Cf5dtgCFoWKil7g