<<I am planning on installing Mountain Hi EDS units and low-pressure lines
in
the overhead air plenum. Connection to the canellas/mask will be behind the
pilot/copilot on the overhead access panel for both front and back seats. I
also plan to install a high pressure gauge in the front of the overhead
plenum using a 1/16 ss capillary line from the tank to the gauge. The tank
will be located in the baggage compartment under a false floor. Part of my
preflight will be to turn the O2 on from the baggage compartment access
door - maybe latter upgrade to a remote turn-on valve.>>

I recently looked at Tom Byrnes' IV (non-pressurized) and he build pretty
much the same system.  Since there are wheels below the baggage compartment
he install the tank behind the aft bulkhead.  I don't remember how he
handled the on-off valve.  My old Cessna had a Bowden cable operated by a
lever in the overhead.  The interesting thing about Tom's system is that he
had 4 outlets for the front passengers, two from the Mountain High system
and two direct outlets labeled "emergency oxygen".  The rear passengers also
got the non-controlled oxygen.  I suggested that in case of the Mountain
High system failure, just borrow the rear passenger oxygen, letting them
fend for themselves until you got down.  I plan to use a portable system,
but I don't know where to put the tank - maybe stand it up on the floor
between the rear seats.

<<But the aviation O2 I have had
serviced in my current aircraft has not always been perfectly dry.  By
the way, where is the control unit, in the cabin or in the baggage
compartment?  Any problem with it being cold?>>

I went through this in great detail before we started using "welding oxygen"
to refill our Cessna system.  The reports we got back from the insiders at
the oxygen suppliers was that there is no water in oxygen tanks.  The only
difference is the price.  The oxygen comes from fractional distillation
(really condensation) of air and there is no way for water to get into the
system.  Same for CO, which is the concern for scuba users.  Besides, any
water in the system would produce instant corrosion of any metal parts.
There is no concern with low temperature operation except that the tank
pressure drops according to temperature.  We had one of our owners that used
welding equipment at his company, so he provided new bottles, which we used
down to about 1500 psi.  He then used that for welding and brought us a new
tank.

Gary Casey
Turbo ES project