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  In the latest edition of Aquacorps (`Hard'), it said that the oxygen supply
in the Newtsuit is controlled by an aqualung regulator with the "water" side
of its diaphragm shut up in a sealed compartment which is set to about 1 bar
pressure, so that as the diver uses up oxygen (and turns it into water vapour
and CO2 which effectively take up no volume because the absorbent absorbs it
all as it is formed), total gas pressure and thus the ppO2 is kept constant.
  But what if some other gas than oxygen gets added to the system, and the
absorber can't absorb it? I am sorry to be scatological, but some foods <do>
make a lot of gas get generated in the intestines, and even if this gas stays
inside the diver it is still inside the suit and distends his body and forms
part of the total gas pressure inside the suit. Then, if the diver starts with
20% ppO2, he ends up with 20% pp(O2 + methane etc) but not necessarily 20%
ppO2. As with previous discussions about outgassed nitrogen/etc adding up to
an appreciable amount in a rebreather circuit, I suspect that gas added to the
system in this way in a closely-fitting hard suit <can> displace an important
proportion of the allowed 20% of a bar ppO2 inside the suit.
  Ditto anything else biological or artificial that expands inside the suit.

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