Dr Deco once bubbled...
Dear blackwater:
1 atmosphere = 10.13 msw
Dr Deco :doctor:
PS Nice to hear from you again, blackwater.
Hi Dr Deco,
I have to confess I had originally assumed, from my flying days, that a standard atmosphere was 1013 millibars and was slightly surprised that the conversion programme, I quoted above, gave it as 1010 millibar (3 sig figs), but rerunning it it seems I misread it. 1013 it is!(to 4 sig figs!). I am sure many of you know that is what pilots use to calibrate their altimeters so they read zero at zero feet altitude AMSL, if the local barometric pressure is not known.
I find it amazing just how hot-under-the-collar some people can get over trivia. It is just as well the internet cannot be used to throw punches!!!
Gentleman, Could I perhaps suggest that for all practical purposes, we accept what blackwater has posted. That;-
1atm = 14.7 psi and
1atm = 33fsw and
1atm = 1.013 bar and
1 bar = 10msw
1 bar = 1 Newton/Sq. meter = 1Pascal.
With the addition of Dr Deco's comment that 1 bar = 14.5 psi.
(Fsw
assumes an accepted standard salinity, which as I tried to make clear, does not exist in reality any more than does a standard barometric pressure - at mean seal level - of 1 atmosphere. Seldom will a diver actually be at a depth of 33 feet in the sea when his manometer reads the equivalent of 1 atm; -33 fsw. I therefore find the terms fsw or msw confusing, simply because they do suggest they are a measurement of depth.)
Feet and psi? Personally I find it much, much, easier to work in metric or SI units and can no longer imagine what it was like when we used £sd (Pounds, shillings and pence) with shillings, thruppenny bits halfpennies and farthings. 240 pennies to the pound, 12 pence to a shilling etc. etc.
We went decimal in 1971 and I remember it well but we survived, just!
My depth guage is calibrated in metres and I challenge anyone to tell me I need to have a more accurate depth meter, whether it is in feet or in centimetres.
As UP and Rick M pointed out, decompression planning is hardly an exact science.
KISS?
