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I have designed a manual non-cryogenic ball valve in SolidWorks (based on this tutorial: https://www.youtube.com/watch?v=pYsU1gfx-00)

My aim is to modify this CAD design so that it becomes cryogenic (LOX to be specific). Then build the prototype using off-shelf components.

My understanding is that the main difficulties that cryogenic ball valves present are:

  1. Thermal contraction, which requires non-cryogenic seals to be modified.

  2. Non-cryogenic lubrication, which is not suitable for cryogenic ball valves.

  3. LOX boil-off: expansion of oxygen when transitioning to gas can make the ball valve explode. Hence, the ball valve needs to be modified so that it realises any excess pressure in its close position. I have read that a possible solution would be to make a hole that is only opened when excess pressure exists.

  4. Mechanical strain.

What type of modifications need to be made on the given SolidWorks design to prevent the difficulties mentioned above, specially LOX boil-off?

Thanks

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    $\begingroup$ this is probably ought to buy, rather than do it yourself $\endgroup$
    – Pete W
    Commented Jan 17 at 23:44
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    $\begingroup$ This is a uni project. If someone could give some guidance would be appreciated. $\endgroup$
    – user71318
    Commented Jan 18 at 11:08
  • $\begingroup$ other considerations, off the top of my head: impact of temperature on sealing materials, compatibility of materials vs pure O2, impact of possible presence of ice crystals etc, flammability considerations (O2 = fire hazard, things that may not burn in air can burn in O2), possibly to include grounding $\endgroup$
    – Pete W
    Commented Jan 18 at 13:58
  • $\begingroup$ I would think lubrication of any kind would be contraindicated by LOX usage. You can eliminate thermal expansion issues by using only 1 material. You could also design the tolerances so that it work only at cryogenic temps. I doubt you could fabricate a prototype cryogenic ball valve without expensive tight tolerance machining. You could 3D print something rough, but it would be visually and dimensionally identical to a regular ball valve at the macro scale. $\endgroup$
    – Drew
    Commented Jan 18 at 15:31
  • $\begingroup$ Consider your material in your operating environment- temperature and humidity. Lower temperatures can make a lot of materials more brittle. Moisture followed by ice formation is an annoyance as it may not not be a material you intentionally chose to include. $\endgroup$
    – Abel
    Commented Jan 19 at 1:44

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