Metre sea water

metre sea water
Hyperbaric chamber pressure gauge calibrated in msw and bar
General information
Unit ofpressure
Symbolmsw
Conversions
1 msw in ...... is equal to ...
   SI units   =10000.0 Pa
   CGS units   =100000 Ba
   U.S. customary   3.263 fsw
 ≈1.45038 psi
foot sea water
Pressure gauge on Siebe Gorman manual diver's pump calibrated in fsw and psi
General information
Unit ofpressure
Symbolfsw
Conversions
1 fsw in ...... is equal to ...
   SI units   3064.3 Pa
   CGS units   30643 Ba
   U.S. customary   0.44444 psi

The metre (or meter) sea water (msw) is a metric unit of pressure used in underwater diving. It is defined as one tenth of a bar.[1][2]

The unit used in the US is the foot sea water (fsw), based on standard gravity and a sea-water density of 64 lb/ft3. According to the US Navy Diving Manual, one fsw equals 0.30643 msw, 0.030643 bar, or 0.44444 psi,[1][2] though elsewhere it states that 33 fsw is 14.7 psi (one atmosphere), which gives one fsw equal to about 0.445 psi.[3]

The msw and fsw are the conventional units for measurement of diver pressure exposure used in decompression tables and the unit of calibration for pneumofathometers and hyperbaric chamber pressure gauges.[4]

  1. ^ a b US Navy Diving Manual 2016, Table 2‑10. Pressure Equivalents..
  2. ^ a b Cite error: The named reference IMCA D022 was invoked but never defined (see the help page).
  3. ^ Page 2-12.
  4. ^ US Navy Diving Manual 2016, Section 18‑2.8.3.