AMRAD at Hamvention
Robert E. Seastrom
rs at seastrom.com
Sun May 13 07:31:06 CDT 2012
Mike ODELL <mo at ccr.org> writes:
> A big issue with H2 tankage is that embrittlement is a serious
> problem which is magnified by the high pressure need to get much H2
> a given volume.
Why didn't I think of that? Answer: I only think about hydrogen
embrittlement when I've got an electrode holder in my hand and am
reaching for the E7018 rather than the E6010 or 6011. So I only
associate it with high temperatures. Funny how high pressure makes
the same thing happen.
> I suspect that makes cylinder re-use a rather riskier proposition,
> enough so that it probably wrecks the usual cylinder gas economics.
> Most places I know of that really use externally supplied H2 take it
> as a cryo-slurry because of the volumetric efficiency of storage and
But folks take delivery in tube trailers too. You'd think they'd
suffer from the same issues. Hydrogen damages both steel and aluminum
- what are the tube trailers made out of?
I know the valves for He are "special" and not just with the outlet
threading (that's connector conspiracy for a good reason, don't want
to hook up dry nitrogen to the medical oxygen line lest you have a
hospital full of dead people). Is it the tanks themselves that you'd
be more worried about? Maybe they just don't last "forever" and need
to be aged out - I've fairly routinely gotten pool tanks for less
aggressive stuff that had ICC approval stamps instead of DOT and first
hydro test stamps that were in the 1930s.
> Btw - it was NASA that figured out how to slurry H2 because that's the
> only way to carry enough to actually use it fuel. Even pure LH2 has crappy
> density compared to slurry. The most amazing part is that it's done easily with a catalyst
> instead of insane pressure and the slurry is far more stable and flows better
> In the fuel lines than pure LH2.
> Just one more area of technology that barely existed at all before Project Apollo -
> Producing, handling, and using cryogens in industrial quantities.
Too cool for the 50s, had to wait for the 60s. I'm hip. :)
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