AMRAD at Hamvention

Robert E. Seastrom rs at
Sun May 13 07:31:06 CDT 2012

Mike ODELL <mo at> 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
> transport.

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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