If I was to put a 5m high tank of fresh water inside an air filled hyperbaric chamber and increase the air pressure within the hyperbaric chamber to 500kpA (roughly 50m equivalent water depth), if i had a water proof pressure gauge at the bottom of the water tank would it read roughly ~550kpA? (I understand that fresh/salt water would have different water pressures)

i.e. when the air pressure is changed inside the hyperbaric chamber, does it have an equivalent effect on the water pressure of a water vessel ?

  • $\begingroup$ It depends on how compressible the water container is (and how tightly sealed). If the container is made of soft rubber then the pressure on the outside will be the pressure on the inside, more or less. If it's heavy steel then there will be little if any correspondence. $\endgroup$ – Hot Licks Mar 7 '18 at 1:22
  • $\begingroup$ I'm assuming your water tank - open at the top inside the chamber. Like an aquarium. $\endgroup$ – docscience Mar 7 '18 at 1:31
  • $\begingroup$ @docscience Your assumption is correct, thanks for clarifying that $\endgroup$ – Jordan Jolly Mar 7 '18 at 3:10

Yes indeed. The pressures (chamber air pressure and tank hydrostatic pressure) add together, the same way they do in an ocean or lake under our 1 atmosphere of pressure. I used to work for US Divers (Now Aqualung Inc.) and we had a man rated hyperbaric chamber in our research lab. To test regulator performance we had a breathing machine (simulator) that connected to the regulator which was placed in an aquarium, all inside the chamber. This effectively provided us performance measures (work of breathing) at various depths.

If you search you'll also find about that same year (circa 1980's) that Jim Middleton at the USN Experimental Diving Unit in Panama City, FLA did similar studies in their hyperbaric chamber and published a report that evaluated all the commercial sport diving regulators at the time.

  • $\begingroup$ You can also study performance in a hypobaric chamber in the same manner. How a regulator will perform at altitude such as in a mountain lake. $\endgroup$ – docscience Mar 7 '18 at 1:32
  • $\begingroup$ @doscience thanks for the answer! The situation you describe is very similar to the one i'm currently in - testing the performance underwater gear at depth of by placing the experiment inside a tank of water, inside a hyperbaric chamber. Good to know our hypothesis was correct! $\endgroup$ – Jordan Jolly Mar 7 '18 at 3:16

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