Decompression curve

A SCUBA Diver makes several stops in order to safely decompress.

Decompression is the act of making many stops during an ascent from depth to allow the dissolved gases, from the breathing gas, to leave the tissues of the body. If a graph of depth/time is plotted, the result is what is known as the decompression curve - it is the profile the diver must follow in order to release the dissolved gas from their body slowly.

How decompression works

Decompression is a mechanism of gas removal from tissues. This is achieved by setting up a "gradient" between the dissolved gas, and the breathing gas as well as the current depth.

Example

assume air O₂ = 20% and N₂ = 80%.

At the surface they body is in equilibrium with the atmosphere (assume only Nitrogen and Oxygen), and the partial pressures of these gases would be 0.8bar and 0.2bar respectively, both inside and outside the body.

Suppose a SCUBA Diver made a dive using air and they descended to 10msw (33 fsw) and stayed there, they would on-gas. This is because the partial pressure of the gases in their body is different to the partial pressure of the gases they are breathing. At 10msw the diver is breathing a gas at 2bar (O₂ = 20% and N₂ = 80% would result in a ppO₂ = 0.4bar and ppN₂ = 1.60bar.)

As stated, the divers' tissues are at a different partial pressure, therefore applying diffusion laws, the gases will try to equalise. Hence the tissues will "load" with gas

If we say that the diver stays at that depth long enough to become saturated with air, so that the sum of partial pressures of the gas in the tissue is equal to the sum of partial pressures of the surrounding environment then the diver would be in equilibrium.

If the diver would to instantaneously arrive on the surface we would find that the tissue partial pressures are greater than the partial pressures of the atmosphere. Which applying diffusion laws, the gas would attempt to leave the tissue to the atmosphere in an attempt to equalise the pressure.

Terminology associated with the decompression curve

Steep If the decompression curve has a steep gradient, we can say that the diver is aggressive because they are forcing dissolved gas out of their tissues. There is a maximum rate of removal before the benefit is minimised by the risk of decompression sickness, or the bends.

This diving-related article is a stub. You can help Wikipedia by expanding it.v · Categories: Diving decompression Underwater diving stubs Wikimedia Foundation. 2010. Игры ⚽ Поможем сделать НИР Formal Public Identifier Killock Shoal Light Look at other dictionaries: Decompression (diving) — Divers decompressing in the water at the end of a dive Decompression in the context of diving derives from the reduction in ambient pressure experienced by the diver during the ascent at the end of a dive or hyperbaric exposure and refers to both …   Wikipedia Decompression sickness — Caisson disease [decompression sickness] Classification and external resources Two United States Navy sailors prepare for training inside a decompression chamber …   Wikipedia Spinal decompression — is a term that describes the relief of pressure on one or many pinched nerves (neural impingement) of the spinal column.[1] Spinal decompression can be achieved both surgically and non surgically and is used to treat conditions that result in… …   Wikipedia Oxygen window in technical diving — Contents 1 Background 2 Application 3 References 4 A …   Wikipedia Dive computer — A watch sized dive computer incorporating an electronic compass and the ability to display cylinder pressure when used with an optional transmitter (Suunto D9) A dive computer or decompression meter is a device used by a scuba diver to measure… …   Wikipedia Technical diving — Technical diver during a decompression stop. Technical diving (sometimes referred to as Tec diving) is a form of scuba diving that exceeds the scope of recreational diving (although the vast majority of technical divers dive for recreation and… …   Wikipedia Diving chamber — The decompression chamber at the Neutral Buoyancy Lab A diving chamber has two main functions: as a simpler form of submersible vessel to take divers underwater and to provide a temporary base and retrieval system in the depths; as a land or ship …   Wikipedia Nitrox — Typical Nitrox cylinder marking Nitrox refers to any gas mixture composed (excluding trace gases) of nitrogen and oxygen; this includes normal air which is approximately 78% nitrogen, 21% oxygen, and 1% other gases, primarily argon.[1][2] …   Wikipedia Deep diving — The meaning of the term deep diving is a form of technical diving.[1] It is defined by the level of the diver s diver training, diving equipment, breathing gas, and surface support: in recreational diving, PADI define anything from 18 metres / 60 …   Wikipedia respiration, human — ▪ physiology Introduction       the process by which oxygen is taken up and carbon dioxide discharged. The design of the respiratory system  The human gas exchanging organ, the lung, is located in the thorax, where its delicate tissues are… …   Universalium 18+ © Academic, 2000-2024 Contact us: Technical Support, Advertising Dictionaries export, created on PHP, Joomla, Drupal, WordPress, MODx. Mark and share Search through all dictionaries Translate… Search Internet Share the article and excerpts Direct link … Do a right-click on the link above and select “Copy Link”