JF Mezei wrote:

You're still not getting it.

On 2016-10-19 06:23, Jeff Findley wrote:

LOX spilled on anything combustible is bad.

Would it be fair to state that the helium filled COPV has some sort of
coating on the outer surface to normally prevent LOX from igniting the
carbon fibre ?


No.


composite). The composite overwrap is in contact with the LOX *at all
times*, because the helium tanks are inside the LOX tank.

So how come the carbon on the outside of helium tank does not combust as
it sits in a pool of LOX ? (see question above).


They're at the top of the tank. Where does the boil-off happen?


And if the LOX became solid, wouldn't it further enhance the
integrity/strength of the helium tank by providing even more support ?


Composite OVERWRAP. The hypothesis is that liquid oxygen got into the
overwrap and froze solid. It is now surrounded by carbon and since it
is solid cannot 'squeeze out' as pressure increases in the LOX tank.


Or does "solid" LOX really mean a slushy mixture, or an actual solid
block of LOX surrounding the helium tank.


A slushy mixture would squeeze back out. It means solid INSIDE THE
OVERWRAP.


Would the helium tank have contributed to the cooling of the LOX to form
an "ice" layer over the COPV tank ?


Jesus, do you not understand what OVERWRAPPED means? Do this. Get an
Ace Elastic bandage. Make a fist. Wrap the elastic bandage around
your fist in multiple layers as tightly as you can. Get a small ice
chip. Force it between the layers of Ace bandage. THAT is what we're
talking about. Your fist is the metal He tank. The bandage is the
composite overwrap. The ice chip is, well, the ice chip.


from a scuba dividng point of view, when you fill scuba tanks and
increase pressure, they get warm


PV=nRT.


If you pour liquid helium in an empty tank at 1ATM, I assume it will at
first evaporate big time and be endothermic. But eventually, won't it
become exithermic once pressure builds up and the liquid no longer
evaporates ?


You're misusing the words 'exothermic' and 'endothermic'. The helium
pressure isn't the issue. OXYGEN pressure is the issue. Oxygen
vaporizes, which increases pressure in the tank until the safety valve
lets it vent. The tank is not being externally pressurized like a
scuba tank on a compressor. It is being internally pressurized by
some of the LOC evaporating.


--
"Ignorance is preferable to error, and he is less remote from the
truth who believes nothing than he who believes what is wrong."
-- Thomas Jefferson