Invicta Divers SCUBA Diving School Frequently Asked Questions (FAQs)
Q. What does the word "SCUBA" mean ?
A. What is the definition of "SCUBA": The word "SCUBA" is an acronym which stands for:
S
elf Contained Underwater Breathing Apparatus
Compared with deep-sea "brass-hat" divers, with lead boots, a large brass watertight helmet with windows in it, and connected to the surface with an umbilical cord for pumping down fresh air and removing stale air, who were winched over the side of a ship or dock and back up again, SCUBA sets divers free to dive when they like, where they like (in all three dimensions), away from the mother ship or shore. SCUBA Divers can respond to, and interact with, what they find underwater in a dynamic way, whereas brass hat divers were limited to walking along the bottom to the limit of the length of the umbilical cord from their support team, above.
The three basic components of SCUBA are:-
* A cylinder filled with compressed air (not oxygen or a special gas) which has been filtered to make it clean and dry.
* A demand-valve regulator to breathe the compressed air through
* A Buoyancy Control Device ("BCD"), sometimes called a buoyancy compensation device, stability ("stab") jacket, or simply known as a jacket or a wing, depending on the design.
You can think of the BCD as being a waistcoat with adjustable air-pockets in it. You wear the waistcoat and attach the cylinder to the back of the waistcoat by means of a strap.
At the top of the cylinder there is a valve with an on-off tap. Into the valve is screwed the clever part of the equipment - the demand valve regulator.
The demand valve regulator is divided into two stages, called the "first stage" and the "second stage". The first stage is screwed into the cylinder valve and connected by a hose to the second stage, which is the part the diver puts in his or her mouth.
The compressed air in the cylinder is at far too high pressure to breathe - the first stage regulates the pressure in the hose down to around 10 Bar (approximately 10 times atmospheric pressure) above the pressure in the water surrounding the diver. The second stage reduces the pressure further, so that it is at just the right pressure for the diver to breathe, no matter how shallow or deep he or she is.
There are other hoses coming out of the first stage - one to a pressure gauge so the diver can read how much air is left, and one going to the BCD so that air can be pumped into the air pockets to give more buoyancy (another valve lets air out). One further hose from the first stage leads to a spare second-stage, in case any other divers run low on air underwater.
It was the invention of the demand valve regulator or "Aqua Lung", credited to Jacques Cousteau in the early 1940s, which really created the "self-contained" ability of SCUBA.
Since its invention, SCUBA has evolved through continuous improvement to the tried-and-tested safe equipment we can all enjoy for recreational diving today.
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