1) Boracay Philippines Scuba Diving
Amature scuba diving, and fish feeding.
2) Busuanga, Palawan, The Philippines
Giant Turtle
Scuba Sets : Hose
"Twin-hose" open-circuit scuba
This is the first type of diving demand valve which came into general use, and the one that can be seen in classic 1960's SCUBA adventures such as TV's Sea Hunt.
In this type of set, the two (or occasionally the one or the three) stages of the regulator are in a large circular valve assembly mounted on top of the cylinder pack. This type has two wide breathing tubes like those on many modern rebreathers, one for intake and one for exhalation. The return tube was not for rebreathing, but because the air exhaust needed to be as near as possible to the regulator's second stage diaphragm, to avoid pressure differences, which would cause a free-flow of gas, or extra resistance to breathing, according to the which way up the diver is in the water. In modern single-hose sets this problem is avoided by moving the second stage regulator to the diver's mouthpiece. The twin-hose sets came with a mouthpiece as standard, but a fullface mask was an option. Another optional extra was a mouthpiece that also had a snorkel attached and a valve to switch between aqualung and snorkel.
Note the correct layout of this type, in the image to the right. In comics there have been thousands of drawings of two-cylinder twin-hose aqualungs shown wrongly, with one wide breathing tube coming straight out of each cylinder top with no regulator.
"Single-hose" open-circuit scuba
Most modern open-circuit scuba sets have a diving regulator consisting of a first stage pressure reducing valve fastened over the diving cylinder's output valve. This valve cuts the pressure from the cylinder, which may be up to 300 bar, to a constant lower pressure, often about 10 bar above the ambient pressure, which is used in the "low pressure" part of the system. A relatively thin low-pressure hose links this with the second-stage regulator, or "demand valve," which is located in the mouthpiece. Exhalation occurs out of a one-way diaphragm in the chamber of the demand valve, directly into the water quite close to the diver's mouth. This configuration type is called "single hose". The first make of this sort of scuba was the Porpoise (make of scuba gear) which was made in Australia.
All modern scuba sets have a spare second-stage demand valve on its own second hose, a configuration called an "octopus" because it often has more hoses for other purposes coming out of the primary regulator on the cylinder top. This second "second-stage" regulator and hose, or "alternate air source", or "safe secondary" or "safe-second" for short, is typically yellow (signalling that it is an emergency or backup device). It is often worn secured into a special friction plug on a diver's chest, easily available to be grabbed by, or offered to, a second diver in trouble for need of air. In so doing, this second mouthpiece eliminates the need for two divers, who need to share a cylinder, to "buddy-breathe" by trading off the same mouthpiece. The original octopus idea was conceived by Sheck Exley as a way for single-file-swimming cave divers to share air in a narrow tunnel, but has now become the standard in recreational diving. Modern "octopus" type primary stage regulators also typically feature high-pressure ports for use by computer sensors, and additional ports for additional low-pressure hoses for inflation of dry suits and buoyancy compensator (BC) devices.
Increasingly, in the 21st century, "safety" secondary mouthpieces have been combined with the inflator and exhaust assembly of buoyancy compensator (BC) devices. This combination eliminates the need for a separate low pressure hose for the BC. Some diving schools now suggest that a diver offer another diver in trouble their primary mouthpiece (i.e. the one in their mouth), before going to their own safe-secondary. The idea here is that the diver not in trouble has much more time to sort things out with his/her own equipment after temporarily losing ability to breathe.
This is the first type of diving demand valve which came into general use, and the one that can be seen in classic 1960's SCUBA adventures such as TV's Sea Hunt.
In this type of set, the two (or occasionally the one or the three) stages of the regulator are in a large circular valve assembly mounted on top of the cylinder pack. This type has two wide breathing tubes like those on many modern rebreathers, one for intake and one for exhalation. The return tube was not for rebreathing, but because the air exhaust needed to be as near as possible to the regulator's second stage diaphragm, to avoid pressure differences, which would cause a free-flow of gas, or extra resistance to breathing, according to the which way up the diver is in the water. In modern single-hose sets this problem is avoided by moving the second stage regulator to the diver's mouthpiece. The twin-hose sets came with a mouthpiece as standard, but a fullface mask was an option. Another optional extra was a mouthpiece that also had a snorkel attached and a valve to switch between aqualung and snorkel.Note the correct layout of this type, in the image to the right. In comics there have been thousands of drawings of two-cylinder twin-hose aqualungs shown wrongly, with one wide breathing tube coming straight out of each cylinder top with no regulator.
"Single-hose" open-circuit scuba
Most modern open-circuit scuba sets have a diving regulator consisting of a first stage pressure reducing valve fastened over the diving cylinder's output valve. This valve cuts the pressure from the cylinder, which may be up to 300 bar, to a constant lower pressure, often about 10 bar above the ambient pressure, which is used in the "low pressure" part of the system. A relatively thin low-pressure hose links this with the second-stage regulator, or "demand valve," which is located in the mouthpiece. Exhalation occurs out of a one-way diaphragm in the chamber of the demand valve, directly into the water quite close to the diver's mouth. This configuration type is called "single hose". The first make of this sort of scuba was the Porpoise (make of scuba gear) which was made in Australia.All modern scuba sets have a spare second-stage demand valve on its own second hose, a configuration called an "octopus" because it often has more hoses for other purposes coming out of the primary regulator on the cylinder top. This second "second-stage" regulator and hose, or "alternate air source", or "safe secondary" or "safe-second" for short, is typically yellow (signalling that it is an emergency or backup device). It is often worn secured into a special friction plug on a diver's chest, easily available to be grabbed by, or offered to, a second diver in trouble for need of air. In so doing, this second mouthpiece eliminates the need for two divers, who need to share a cylinder, to "buddy-breathe" by trading off the same mouthpiece. The original octopus idea was conceived by Sheck Exley as a way for single-file-swimming cave divers to share air in a narrow tunnel, but has now become the standard in recreational diving. Modern "octopus" type primary stage regulators also typically feature high-pressure ports for use by computer sensors, and additional ports for additional low-pressure hoses for inflation of dry suits and buoyancy compensator (BC) devices.
Increasingly, in the 21st century, "safety" secondary mouthpieces have been combined with the inflator and exhaust assembly of buoyancy compensator (BC) devices. This combination eliminates the need for a separate low pressure hose for the BC. Some diving schools now suggest that a diver offer another diver in trouble their primary mouthpiece (i.e. the one in their mouth), before going to their own safe-secondary. The idea here is that the diver not in trouble has much more time to sort things out with his/her own equipment after temporarily losing ability to breathe.
What is scuba ?
Scuba diving is the term used to describe the use of a self-contained breathing set to stay underwater for periods of time greater than the average individual can breath-hold. The diver carries all equipment necessary for diving and is not reliant upon equipment elsewhere (e.g. on the surface) to supply breathing gas or other support during the dive. The diver swims underwater using fins attached to his/her feet. Some divers also move around with the assistance of a DPV (Diver Propulsion Vehicle), commonly referred to as a "scooter", or by using surface-tethered devices called sleds, which are pulled by a boat.The word 'SCUBA' is an acronym for "Self Contained Underwater Breathing Apparatus", but it has become acceptable to refer to 'scuba equipment' or 'scuba apparatus'. The term SCUBA in common usage usually means open-circuit equipment in which gas (usually air) is breathed from a tank of compressed gas and then exhaled into the water, usually in the line of kit development started by Emile Gagnan and Jacques-Yves Cousteau. But rebreathers (both semi-closed circuit and closed circuit) are also self-contained systems and could be classed as SCUBA. The term SCUBA arose during WWII and originally meant USA combat frogmen's oxygen rebreathers.
Within recreational diving there are those who are considered professional divers, because they maintain a professional standard of training and skills (and must, in theory, according to the laws of the area, carry professional liability insurance).
Some consider Technical Diving to be a subset of recreational diving, but others separate it out due to the extensively different training equipment and knowledge needed for technical dives.
Public safety diving and military diving might likewise be classified as commercial diving because public safety divers and military divers make a living from their pursuit of diving. However, public safety divers (police or rescue) and military divers have a different mission from the typical commercial diver.
Scientific diving is used by marine scientists, including marine biologists, as a tool for collecting their research data
Credit to http://en.wikipedia.org/wiki/Scuba_diving
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