Buoyancy of gas-filled bladders at great depth. (February 2018)

• Record Type: Journal Article
• Authors: Priede, Imants G.
• Is Part Of: Deep sea research. Volume 132(2018)
• Page Start: 1
• Page End: 5
• Publication Date: 2018-02
• Subjects: Swim bladder -- Buoyancy -- Density -- Oxygen -- Nitrogen -- Air; Oceanography -- Periodicals; Océanographie -- Périodiques; 551.4605
• DOI: 10.1016/j.dsr.2018.01.004
• Languages: English
• ISSNs: 0967-0637

Abstract

Abstract: At high hydrostatic pressures exceeding 20 MPa or 200 bar, equivalent to depths exceeding ca. 2000 m, the behaviour of gases deviates significantly from the predictions of standard equations such as Boyle's Law, the Ideal Gas Law and Van der Waals equation. The predictions of these equations are compared with experimental data for nitrogen, oxygen and air at 0 °C and 15 °C, at pressures up to 1100 bar (110 MPa) equivalent to full ocean depth of ca . 11000 m. Owing to reduced compressibility of gases at high pressures, gas-filled bladders at full ocean depth have a density of 847 kg m −3 for Oxygen, 622 kg m −3 for Nitrogen and 660 kg m −3 for air providing potentially useful buoyancy comparable with that available from man-made materials. This helps explain why some of the deepest-living fishes at ca . 7000 m depth (700 bar or 70 MPa) have gas-filled swim bladders. A table is provided of the density and buoyancy of oxygen, nitrogen and air at 0 °C and 15 °C from 100 to 1100 bar. Highlights: The weight of compressed gases at great depths limits the buoyancy gas bladder systems can provide. Densities and buoyancy in sea water of oxygen, nitrogen and air at 0 °C and 15 °C are tabulated to 1100 bar. Gas-filled swim bladders or air bags can provide buoyancy at full ocean depth. This explains why some of the deepest living fishes have gas filled swim bladders.