This site contains a wealth of information relating to the many aspects of scuba diving in the UK.

Latest News

Weather and Tides



A  B  C  D  E  F  G  H  I  J  K  L  M  N  O  P  Q  R  S  T  U  V  W  X  Y  Z  #


Search the site



Glossary - O

02 Oxygen
Octopus An extra breathing second stage for use in the event of a failure or an out-of-gas emergency with a diving buddy. They are usually coloured yellow.
OD  Ocean Diver (BSAC)
Off Gassing The process of eliminating excess dissolved gasses from the body. The reverse of ongassing, more commonly referred to as decompression.
On Gassing As a person breathes air or any mixture of gases, a portion of those gases are absorbed through the lungs into the blood stream. Ongassing occurs primarily in the alveoli of the lungs (though it does occur at all levels, lungs, blood, tissues). This absorbed (or dissolved) gas is carried dissolved in the bloodstream and diffuses from areas of high partial pressure to areas of lower partial pressure throughout the various tissues (or compartments). As oxygen is metabolised it is "generally" not considered to be ongassing but does have limits as to how much can be absorbed safely. Excessively high partial pressures of oxygen can be absorbed and contribute to DCS, so ongassing as a term can be applied to oxygen. However, the partial pressures that can cause this are higher than those considered safe in relation to CNS O2 toxicity, so this is more an academic concern, rather than a real concern.
OT  Oxygen Toxicity
Otitis Otitis Externa - Inflammation of the external auditory canal due to infection.
Otitis Media - Inflammation of the middle ear. This condition generally require treatment with antibiotics and may cause impairment of balance.
Outboard An engine and propeller arrangement usually attached to the stern of the boat. The entire unit can be turned to provide steering capability.
Overfalls Overfalls occur when the depth and configuration of the seabed, combine with localised tidal streams or eddies.  These can be seen as breaking waves caused by a strong tidal stream crossing rapidly shoaling water, an irregular bottom or an underwater obstruction.  To remember the chart symbols, eddies are localised swirling of water.  Overfalls ripple over the top
OW Open Water
OWI Open Water Instructor (BSAC)
Oxygen A colourless, tasteless, odourless, non-flammable gas that accounts for 20.95% of the air we breathe.
Oxygen Cleaned Refers to the cleanliness of the system or component, or more specifically, the absence of contaminants. Contaminants vary but the most serious are those that act as a source of combustion such as oil, grease, paint, fingerprints, soot, lint, dust, metal particles, rust, cleaning solvents, and cleaning detergents. New SCUBA equipment is generally NOT oxygen clean.
Oxygen Service Refers to the suitability of a system or component for use in an oxygen environment. Oxygen service requires both oxygen clean and oxygen compatible components.
Oxygen Toxicity Short or long term physiological effects of elevated partial pressures of Oxygen. Also referred to as CNS Oxygen Toxicity.










Copyright 2004/5. All Rights Reserved.
Page last updated on October 16, 2007
Webmaster : Site Map : Disclaimer