-> This brings to mind something I saw up in that area (don't know what
-> but I'd guess it was in New Jersey, Delaware, or Maryland) about 30 y
-> ago:  On the approach to a tunnel, there were signs saying that vehic
-> with, or pulling trailers with, gas bottles were not to use the tunne
-> were instead to use an open-air route.  The driver of the car I was i
-> failed to acknowledge these signs, and we were pulled over and reques
-> take that other route.  Might some tunnels have less than optimum att
MR> I've heard that some bottles of compressed gas can and will
MR> explode under the low pressures of going under the water,
MR> i've also heard it wont. But i dont take channses and just
MR> leave my bottles, at home, this goes for Propane, Nitrise
MR> Oxide, and compressed oxygen for scuba tanks. 
They won't.  One of the highest pressure tanks are
scuba tanks (which are filled with compressed air not
compressed oxygen).  Aluminum tanks are filled to a
working pressure of 3000 psi but they are tested and
must pass a 5000 psi test.  IOW, the tanks are only
filled to 3/5's or 60% of their tested pressure.
The last time I check any other type of tank, a helium
tank, it was filled to 2000 psi.  I'm not sure what the
test is but they have to be tested (and have the date
of the test stamped into the tank).
A lot of companies do refuse to fly tanks but some do.
                      Remember:  Freedom isn't Free!
--- timEd-B11
---------------