LouieLouie
Contributor
Aaargh. Use proper SI units for pressure, and everything else for that matter, and we no longer have to waste time on silly things like this.
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From the chart above, here are your answers:
100 x 0.445138889 PSI/FSW = 44.5138889 PSI
30½ MSW x 0.100693064 Bar/MSW = 3.071138462 Bar
I'm sorry, but that doesn't solve my problem with the paragraph I quoted in the first post:
"The conversion between feet and meters of sea water is 1 fsw = 0.307 msw. This conversion is for the pressure units (msw and fsw), not the units of length,meter and foot which is : 1 ft = 0.305 m."
Because, no matter which path or precision you follow, these four premises can't be all true at the same time:
A - 1 fsw = 0.307 msw
B - 1 ft = 0.305 m
C - 1fsw = 1ft of sea water
D - 1msw = 1m of sea water
A and B come from the quote. C and D are what I thought to be axioms and must not be (which I'm trying to understand).
Because, if A, B, C and D are all true, by reductio ad absurdum:
[C] Under 1ft of water one has 1fsw,
[A] which is 0.307 msw,
[D] which is 0,307 meters under water
which is >1ft
And 1ft cannot be >1ft.
Thus, taking into account the quote comes from a respected diving manual, either C or D must be false. Which is what I still don't understand.
I'm sorry, but that doesn't solve my problem with the paragraph I quoted in the first post:
"The conversion between feet and meters of sea water is 1 fsw = 0.307 msw. This conversion is for the pressure units (msw and fsw), not the units of length,meter and foot which is : 1 ft = 0.305 m."
Because, no matter which path or precision you follow, these four premises can't be all true at the same time:
A - 1 fsw = 0.307 msw
B - 1 ft = 0.305 m
C - 1fsw = 1ft of sea water
D - 1msw = 1m of sea water
A and B come from the quote. C and D are what I thought to be axioms and must not be (which I'm trying to understand)
Because, if A, B, C and D are all true, by reductio ad absurdum:
[C] Under 1ft of water one has 1fsw,
[A] which is 0.307 msw,
[D] which is 0,307 meters under water
which is >1ft
And 1ft cannot be >1ft.
Thus, taking into account the quote comes from a respected diving manual, either C or D must be false. Which is what I still don't understand.
It's true, T, that he didn't mention fresh water, and it's possible that this additional information will confuse him even further, but to my mind, it shows that pressure is relative to the medium, regardless of the linear dimension of that medium.Except in the quote of the OP the argument was that while 1ft = 0.305 m, 1 fsw = 0.307 msw, and never mentioned freshwater with a single letter...
I might be tired, but to me the quote of the OP seems to be just wrong tho.. If youre submerged 1 foot in seawater you are submerged 0.305 meters in seawater as well, and not magically 0.002 meters deeper because youre in the water instead of on land..
Assuming Ihave understood the explanations given me properly, the confusion you are having is this:
feet -> meters is a linear conversion
fsw -> msw is a pressue conversion
fsw <> feet, and msw <> meters.
Does that help?