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Day 4 – Monday, April 30
SCUBA is an acronym that stands for Self-Contained Underwater Breathing Apparatus. In 1942-43, Jacques Costeau and Emile Gagnan developed the Aqua Lung, the precursor to modern day SCUBA, from a redesigned car regulator. Designs have evolved over the years, but the principles remain the same. To this day, SCUBA remains an essential component to most marine science research as it enables scientists to interact hands-on with the underwater environment as opposed to using cameras or other remotely operated devices.
Modern SCUBA gear consists of the following items:
Scuba tank or Cylinder
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Attaching two stage reguator to scuba tank
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Cylinder – Commonly referred to as a tank, cylinders are made of aluminum or steel, and contain compressed air, air that is enriched with oxygen, or air mixed with other gases (i.e., helium). The maximum amount of compressed air that a tank can be filled with depends upon the size of the tank, but most tanks are filled to 3000 PSI (pounds per square inch).
Two-Stage Regulator – The first stage regulator reduces the cylinder pressure from 3000 PSI to an intermediate level of about 145 PSI. The second stage demand valve regulator, connected via a low pressure hose to the first stage, delivers the breathing gas at the correct ambient pressure to the diver's mouth and lungs. The diver's exhaled gases are exhausted directly to the environment as waste. The first stage typically has at least one "high pressure" outlet, which delivers breathing gas at unreduced tank pressure. This is connected to the diver's pressure gauge to show how much breathing gas remains.
Amy with bouyancy vested tank, regulator, inflator hose
and button, and high pressure outlet to pressure/depth guage.
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With an inflatable vest, the diver is able to
control buoyancy by filling or bleeding air
from it while under water
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Buoyancy Compensator – Often shortened to BC, this piece of equipment is an inflatable vest that the diver is able to fill with air in order to control his/her buoyancy while under water. The BC attaches to the tank via a velcro strap and buckle. Divers need to adjust their buoyancy underwater in order to safely control ascent and descent rates. The inflator hose from the regulator inserts into a hose on the BC, and air is delivered to the BC by depressing a button.
varying amounts of weights attached
to help with buoyancy.
Weight Belt – Like the name implies, the weight belt is a belt that a diver wears to which varying amounts of weight may be attached. The weight belt, like the BC, aids in buoyancy control.
Wet suit – A body suit made of neoprene rubber foam. Water absorbed by the wetsuit is heated by the skin and provides an insulating layer. Wetsuits come in varying thicknesses. Thicker wetsuits provide more insulation than thinner ones.
based on a pre-programmed algorithm
Dive Computer – Typically worn on the diver’s wrist like a watch, the computer constantly measures depth and time, based on a pre-programmed algorithm. The computer also calculates tissue nitrogen uptake and elimination and provides a continuous readout of the dive profile, including: depth, elapsed time of the dive, duration at current depth before decompression becomes mandatory, and a warning if the rate of ascent is too fast.
Pressure and depth Guages
a vital piece of equipment
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Here we see scientist Sean Meehan fully
equipped and monitoring his depth,
pressure, and dive time during his ascent.
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Pressure/Depth Gauge - These gauges show how much breathing gas remains in the tank and also display the diver’s depth throughout the dive.