divespot.com.ph will give you much information about diving.
There are truly four 'small histories' in the interesting story of man's yearning to investigate underneath the ocean; they relate to four different routines for diving, of which scuba is however the most recent.
1. Breath-hold diving (free diving, skin diving). This earliest form of diving is still honed for both sport and commercial purposes. The breath-hold diver’s compressible air spaces are crushed by the expanded water weight all around the dive. Each one dive, restricted by the individual's tolerance for breath-hold and the danger of suffocating from hypoxia, is generally a moment or less.
2. Diving in a heavy-walled vessel. Heavy-walled vessels can maintain their internal atmosphere at or near sea level pressure, and so prevent the surrounding water pressure from affecting the occupants. Such vessels include: the bathysphere, an unpowered hollow steel ball lowered from the mother ship by steel cable: the bathyscaphe, a bathysphere with buoyancy control so that cable is not needed for descent and ascent: and the submarine, which can travel great distances in any direction under its own power. All one-atmosphere vessels require a system to both provide fresh air (usually by adding oxygen to the existing air) and get rid of exhaled carbon dioxide (with soda lime, lithium hydroxide, or a similar compound that takes up CO2). A modern extension of the one-atmosphere vessel is the self-contained armored diving suit, adaptable yet equipped to withstand weights at profundity: basically, the diver gets to be just about like a little submarine. With these one-environment suits a diver can work at a profundity of several hundred meters for hours.
3. Diving with compressed air supplied from the surface. The diver is separated from the supply of fresh air, which is kept on the surface. Air achieves the diver through a long umbilical, which in its easiest structure closes in a controller and mouthpiece conveyed by the diver. In more modern frameworks the umbilical leads into a dive suit or some bigger encased space holding the diver. Devices in this category include caissons (huge spaces supplied with compressed air, employed mainly for bridge and tunnel work), underwater habitats used for saturation diving, diving bells, and rigid-helmet diving suits. In all these devices, the diver breathes air at the same pressure as the surrounding water pressure, and so is at risk for decompression problems (bends, air embolism, etc.) if ascent is too fast. Special ‘high tech’ mixtures, such as hydrogen-oxygen, helium-oxygen, and helium-nitrogen-oxygen, are used to dive deeper than possible with compressed air.
4. Diving with compressed air or other gas mixture that is carried by the diver (scuba diving). There are two principle types of scuba: open and closed circuit. Open circuit vents all expired air into the water, and is the mode used in recreational diving. Closed circuit systems, in which exhaled air is re-breathed after carbon dioxide is absorbed and oxygen added, were widely used before open circuit became available, particularly by military divers who wished to avoid showing any air bubbles. Likewise with divers utilizing surface-supplied compacted air, scuba divers are at danger for decompression problems on the off chance that they climb without fitting decompression. Helium-oxygen and other mixtures can be used to go deeper than possible with compressed air.
Thursday, May 29, 2014
Diving - The Early History
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Individuals have had a devouring enthusiasm toward going underneath the ocean for a long time. Aged original copies hold portrayals of right on time divers. Extremely old stuff infers that individual bird for materials for adornments, for example, pearls. Greek writing alludes to right on time wipe divers. Herodotus (500 B.C.) recounts the story of Scyllis, a Greek mariner, who utilized a reed to inhale as he cut the mooring lines of Persian ships. This interest pushed people to develop ever-improving methods of staying underwater for longer periods of time and at ever increasing depths.
Men and women have practiced breath-hold diving for centuries. Indirect evidence originates from thousand-year-old undersea antiques found ashore (e.g., mother-of-pearl decorations), and portrayals of divers in aged drawings. In old Greece breath-hold divers are known to have chased for wipes and occupied with military adventures. Of the latter, the story of Scyllis (sometimes spelled Scyllias; about 500 BC) is perhaps the most famous. As told by the 5th century BC historian Herodotus (and quoted in numerous modern texts).
"During a naval campaign the Greek Scyllis was taken aboard ship as prisoner by the Persian King Xerxes I. When Scyllis learned that Xerxes was to attack a Greek flotilla, he seized a knife and jumped overboard. The Persians could not find him in the water and presumed he had drowned. Scyllis surfaced at night and made his way among all the ships in Xerxes's fleet, cutting each ship loose from its moorings; he used a hollow reed as snorkel to remain unobserved. Then he swam nine miles (15 kilometers) to rejoin the Greeks off Cape Artemisium."
The desire to go under water has likely constantly existed: to hunt for food, uncover artifacts, repair ships (or sink them!), and maybe simply to watch marine life. Until people figured out how to breathe under water, notwithstanding, each one dive was fundamentally short and frenzied.
How to stay under water longer? Breathing through an empty reed permitted the body to be submerged, however it must have gotten obvious immediately that reeds more than two ft long don't work well; trouble breathing in against water weight adequately breaking points snorkel length. Breathing from an air-filled bag brought under water was also tried, but it failed because of rebreathing of carbon dioxide.
In the sixteenth century, individuals started to utilize diving ringers supplied with air from the surface, presumably the first powerful method for staying submerged for any time allotment. The chime was held stationary a couple of ft from the surface, its bottom open to water and its top bit holding air packed by the water weight. A diver standing upright would have his head circulating everywhere. He could leave the ringer for a moment or two to gather wipes or investigate the bottom, then return for a short while until air in the chime was no more breathable.
In sixteenth century England and France, full diving suits made of leather were utilized to profundities of 60 ft. Air was pumped down from the surface with the help of manual pumps. Before long caps were made of metal to withstand much more stupendous water weight and divers went deeper. By the 1830s the surface-supplied air cap was idealized fine to permit far reaching rescue work.
Beginning in the nineteenth century, two primary avenues of investigation - one scientific, the other technologic - enormously quickened underwater exploration. Scientific research was propelled by the work of Paul Bert and John Scott Haldane, from France and Scotland, separately. Their studies helped clarify impacts of water weight on the body, and likewise characterize safe cutoff points for layered air diving. In the meantime, enhancements in technology - layered pneumatic machines, carbon dioxide scrubbers, controllers, and so on., made it feasible for individuals to stay under water for long periods.
Individuals have had a devouring enthusiasm toward going underneath the ocean for a long time. Aged original copies hold portrayals of right on time divers. Extremely old stuff infers that individual bird for materials for adornments, for example, pearls. Greek writing alludes to right on time wipe divers. Herodotus (500 B.C.) recounts the story of Scyllis, a Greek mariner, who utilized a reed to inhale as he cut the mooring lines of Persian ships. This interest pushed people to develop ever-improving methods of staying underwater for longer periods of time and at ever increasing depths.
Men and women have practiced breath-hold diving for centuries. Indirect evidence originates from thousand-year-old undersea antiques found ashore (e.g., mother-of-pearl decorations), and portrayals of divers in aged drawings. In old Greece breath-hold divers are known to have chased for wipes and occupied with military adventures. Of the latter, the story of Scyllis (sometimes spelled Scyllias; about 500 BC) is perhaps the most famous. As told by the 5th century BC historian Herodotus (and quoted in numerous modern texts).
"During a naval campaign the Greek Scyllis was taken aboard ship as prisoner by the Persian King Xerxes I. When Scyllis learned that Xerxes was to attack a Greek flotilla, he seized a knife and jumped overboard. The Persians could not find him in the water and presumed he had drowned. Scyllis surfaced at night and made his way among all the ships in Xerxes's fleet, cutting each ship loose from its moorings; he used a hollow reed as snorkel to remain unobserved. Then he swam nine miles (15 kilometers) to rejoin the Greeks off Cape Artemisium."
The desire to go under water has likely constantly existed: to hunt for food, uncover artifacts, repair ships (or sink them!), and maybe simply to watch marine life. Until people figured out how to breathe under water, notwithstanding, each one dive was fundamentally short and frenzied.
How to stay under water longer? Breathing through an empty reed permitted the body to be submerged, however it must have gotten obvious immediately that reeds more than two ft long don't work well; trouble breathing in against water weight adequately breaking points snorkel length. Breathing from an air-filled bag brought under water was also tried, but it failed because of rebreathing of carbon dioxide.
In the sixteenth century, individuals started to utilize diving ringers supplied with air from the surface, presumably the first powerful method for staying submerged for any time allotment. The chime was held stationary a couple of ft from the surface, its bottom open to water and its top bit holding air packed by the water weight. A diver standing upright would have his head circulating everywhere. He could leave the ringer for a moment or two to gather wipes or investigate the bottom, then return for a short while until air in the chime was no more breathable.
In sixteenth century England and France, full diving suits made of leather were utilized to profundities of 60 ft. Air was pumped down from the surface with the help of manual pumps. Before long caps were made of metal to withstand much more stupendous water weight and divers went deeper. By the 1830s the surface-supplied air cap was idealized fine to permit far reaching rescue work.
Beginning in the nineteenth century, two primary avenues of investigation - one scientific, the other technologic - enormously quickened underwater exploration. Scientific research was propelled by the work of Paul Bert and John Scott Haldane, from France and Scotland, separately. Their studies helped clarify impacts of water weight on the body, and likewise characterize safe cutoff points for layered air diving. In the meantime, enhancements in technology - layered pneumatic machines, carbon dioxide scrubbers, controllers, and so on., made it feasible for individuals to stay under water for long periods.
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