topic 4

• • SCUBA stands for
  • Self
  • Contained
  • Underwater
  • Breathing
  • Apparatus
• • At greater water pressures (deeper water) nitrogen gas dissolves in our blood and tissues at a much higher concentration than normal
  • If a diver ascends slowly to the surface, the extra gas leaves the body naturally as the water pressure decreases
  • A problem arises when the diver ascends too quickly (water pressure is decreasing too rapidly)
• • Decompression sickness, called “The Bends” can result
  • The sudden change in pressure causes nitrogen gas to bubble out of the blood and tissues
  • These bubbles can collect in body other parts and cause considerable pain
  • Death can occur if not treated
• treating the bends: One treatment is to place the affected diver in a special chamber

  • This chamber increases the pressure surrounding the divers body
  • The greater pressure forces the gas bubbles to dissolve back into the blood and tissues
  • By very slowly decreasing the pressure back to normal, the gas slowly leaves the body
• • Pump is a device that moves a fluid through, or into something
  • Example: You use a pump to fill a basketball 

      with air

  • Pumps also exist in nature
  • Example: The human heart
  • Pumps blood throughout your body
• • Diaphragm: used for both liquids and gasses
  • Pull the piston up and fluid flows in
  • Push the piston down and fluid flows out
  • Works like your diaphragm for breathing
  • Archimedes Screw: invented by Archimedes to remove water from the hold of a ship
  • Screw turns and brings water up
• • Has a piston that moves up and down in a cylinder
  • This compresses the air
  • The pressure of the air in the pump therefore increases
  • If the opening at the bottom of the cylinder is connected to an area of lower pressure, the air will move to that area
• • A computerized unit called a “pig” is placed in the pipeline and pushed through it by the moving gas
  • The “pig” cleans the pipe with brushes as it moves through
  • At the same time the “pig’s” sensors check the pipe and record its condition so any necessary repairs can be made
• • Valves - devices used to control or regulate the amount of flow of fluids (liquid or gas)
  • Today’s valves also control 

      the rate, volume, pressure, 

      and direction of flow
• • Humans can NOT dive this deep-too much pressure
  • To go this deep you would need an underwater ship called a bathyscaph
  • Bathyscaph-comes from the Greek words bathos-for “deep” and scaphos-for ship
  • Consists of a large float with a metal sphere underneath (this is where the people sit)
• • Called ROPOS
  • Remotely
  • Operated
  • Platform for
  • Ocean
  • Science
• • Most fish use a swim bladder to change their buoyancy
  • This is a gas-filled sac found just under the backbone
  • Dissolved gases in the fish’s blood move into the sac to give it greater buoyancy
  • The swim bladder empties when the fish wants to dive deeper
• • Submarines have air tanks called ballast tanks between the inner and outer hulls of the submarine
  • Submarines also carry compressed air tanks used in resurfacing
• • To resurface, compressed air is forced through the valves at the top
  • This forces the seawater out of the bottom valves
  • The density of the submarine with air in the tanks becomes less than the density of the water
  • This causes the submarine to rise to the surfac