OPEN WATER DIVE TRAINING ADVANCED

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OPEN WATER DIVE TRAININGADVANCED

• DIVING PHYSICS

STAN JACKSON UICC 5303
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REVIEW

• Sound travels about 5000 feet per second in salt
  water or about four times faster in water than
  air.
• Underwater, objects appear 25 closer and 33
  larger.
• Water conducts heat more than 20 times faster
  than air.
• Atmosphere or Air
• At sea level, atmospheric pressure is equal to
  14.7 psi.
• or one atmosphere (ATA) or (ATMA). Air
  contains
• 21 Oxygen, 78 Nitrogen and 1 other
  gasses.

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PRESSURE

• Atmospheric The pressure exerted by the earths
  atmosphere. (14.7 psi) 18,000 feet 7.35 psi
• Hydrostatic Pressure due to the weight of
  water. .445 psi per foot of seawater
  or 14.7 psi per 33 feet. .432 psi per foot
  of freshwater or 14.7 psi per 34 feet.
• Absolute Pressure The sum of atmospheric and
  hydrostatic pressure. (ATA or ATMA)
• Gauge Pressure The difference between
  atmospheric pressure and the pressure being
  measured.

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PRESSURE

• Hydrostatic Pressure How did we get .445 psi
  per foot of seawater and .432 psi per foot of
  freshwater?
• What is the absolute pressure at 62 fsw?
• What is the absolute pressure at 112 ffw?

.445 psi x 62 fsw
27.59 psi
14.7 psi
42.29 psia
.432 psi x 112 fsw
48.38 psi
14.7 psi
63.08 psia
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PRESSURE

• Hydrostatic Atmospheres (working with)
• What is the absolute pressure (ATA) at 62 fsw?
• What is the absolute pressure (ATA) at 112 ffw?

2.88 ATA
4.29 ATA
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Gas Gas
Depth Pressure
Volume Density
PRESSURE CHART

• Sea Level 14.7 psia 1 ata
  1 cu ft 1x
• 33 feet 29.4 psia 2 ata
  1/2 cu. ft. 2x
• 66 feet 44.1 psia 3 ata
  1/3 cu. ft. 3x
• 99 feet 58.8 psia 4 ata
  1/4 cu. ft. 4x
• 132 feet 73.5 psia 5 ata
  1/5 cu. ft. 5x
• 165 feet 88.2 psia 6 ata
  1/6 cu. ft. 6x

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DENSITY

• Density weight per unit volume. (pounds per
  cubic foot)
• - Density Weight / Volume or D W / V
• Seawater one cubic foot equals 64 lbs. (fsw)
• Freshwater one cubic foot equals 62.4 lbs.
  (ffw)
• Density (Gas) is related to absolute pressure.
  As depth increases, the density of the breathing
  gas increases and becomes heavier per unit volume.

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DENSITY

• Density weight per unit volume.
• D W / V

Multiply both sides by volume
Divide both sides by density
D Density of water W Total weight of diver V
Water displaced (volume)
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DENSITY

• If we have a diver in saltwater and he wants to
  dive in freshwater, how much weight will he need
  to remove?
• First we need to know the volume of the diver in
  saltwater.
• Total weight of diver.
• Density of saltwater.
• 
  
• Now we
  know the volume of the diver. Next we can find
  out how much freshwater he will displace.
• W V x D 3.875 cu. ft. x 62.4 lbs.
  241.8 lbs.
• 248 lbs. 241.8 lbs. 6.2 lbs. Remove!

180 lbs. Diver 50 lbs. Equipment 18 lbs.
Weight belt 248 lbs. Total weight
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DENSITY

• A dive team wants to recover (lift) a 432 pound
  (dry weight) anchor from the bottom of the ocean.
  The anchor displaces 3.5 cu. ft. of sea water.
  The bottom is flat and firm. How many 50 pound
  lift bags will it take to recover (lift) the
  anchor to the surface?
• 
  
• W V x D 3.5 cu. ft. x 64 lbs. 224 lbs.
• 224 lbs. 50 4.48 bags

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TEMPERATURE

• Temperatures must be converted to absolute when
  the gas laws are used.
• Rankine Based on Fahrenheit scale. R F 460
• Kelvin Based on Celsius scale. K C 273
• F (9/5 x C) 32
• C 5/9 x (F 32)

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GAS LAWS

• Boyles Law of Pressure and Volume If the
  temperature is kept constant, the volume of a gas
  will vary Inversely with the absolute pressure.
• A sealed flexible
  container at the surface
• has a volume of 10
  liters. The container is submerged to a depth
  of 79 feet in the ocean. What is the volume of
  the container at 79 fsw?

Divide both sides by
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GAS LAWS

• Boyles Law of Pressure and Volume If the
  temperature is kept constant, the volume of a gas
  will vary Inversely with the absolute pressure.
• A sealed flexible
  container at the surface
• has a volume of 10
  liters. The container is submerged to a depth
  of 79 feet in the ocean. What is the volume of
  the container at 79 fsw?

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Ratio or Percentage

• If a cylinder contains 80 cu. ft. of air at 3000
  psig, how many cubic feet of air remains if the
  cylinder pressure is reduced to 2200 psig?
  (temperature remains constant)
• Percentage

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GAS LAWS

• Charles Law of Temperature and Volume If the
  pressure is kept constant, the volume of the gas
  will vary directly with the absolute temperature.
• If a balloon at the surface has 12 cu. ft. of air
  at 86ºF, what would the balloons volume be at
  55F?
• First determine absolute temperatures.
• 86F 460 546R
• 55F 460 515R

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GAS LAWS

• Gay-Lussacs Law of Pressure and Temperature
  With a constant volume, the pressure of a gas
  will vary directly with the absolute temperature.
• A scuba cylinder contains 3000 psi. at 64F. It
  is left on the boat deck, on a hot summer day.
  What will the cylinder pressure be if the
  temperature of the air inside reaches 102F?
• 64F 460 524R 3000 psi.
  14.7 psi.
• 102F 460 562R
  3014.7 psia.

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GAS LAWS

• Daltons Law of Partial Pressures The total
  pressure exerted by a mixture of gases is equal
  to the sum of the pressures of each of the
  different gases making up the mixture.
• The partial pressure of oxygen in air at a depth
  of 128 fsw is
• Henrys Law of Dissolved Gases The amount of any
  given gas that will dissolve in a liquid at a
  given temperature is proportional to the partial
  pressure of that gas.

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GAS LAWS

• General Gas Law or Ideal Gas Law is a
  combination of Boyles and Charles Law.
• An open diving bell
  of 24 cu. ft. capacity
• is lowered to 99
  fsw. Surface temperature is 80F and the depth
  temperature is 45F. What is the volume in the
  bell at depth?
• The volume was reduced, due to the drop in
  temperature and the increase in outside pressure.

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GAS LAWS

• Archimedes Principle of Buoyancy Any object
  wholly or partly immersed in a fluid is buoyed up
  by a force equal to the weight of the fluid
  displaced by the object.
• You have an object that weighs 300 lbs. and
  displaces 4.5 cubic feet of saltwater.
• Will the object float or sink?
• 
  300 lbs.
• W D x V 64 lbs. x 4.5 cu. ft. 288 lbs.
• 
  12 lbs. (sink)

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SURFACE AIR CONSUMPTION

• SAC Rate At the surface, note the beginning
  pressure on your gauge. Swim at the surface for
  10 minutes (moderate work load) then note your
  ending pressure.
• Aluminum 80 _at_ 3000 psi
• Start 3000 psi ending 2500 psi 500 psi
  used.
• 500 psi 10 minutes 50 psi per minute, at the
  surface.
• 50 psi per minute x ata Depth Air
  Consumption.
• Problem A diver has a SAC of 40 psi per minute.
  The diver wants to know how long their air will
  last at a depth of 62 feet in sea water. Assume
  aluminum 80 _at_ 3000 psi.

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SURFACE AIR CONSUMPTION

• First Assume, Aluminum 80 _at_ 3000 psi.
• 3000 psi 500 psi (reserve) 2500 psi.
• 2500 psi 40 psi 62.5 minutes at the
  surface.
• ata
• (SACR) 40 psi x (Depth in ata) 2.88 ata
  DACR
• DACR 40 psi x 2.88 ata 115.2 psi per
  minute.
• 2500 psi 115.2 psi 21.7 minutes at depth.

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KEY POINTS

• Sound travels 4 times faster in water.
• Objects appear 25 closer and 33 larger
  underwater.
• Atmospheric Pressure Air column.
• Hydrostatic Pressure Water.
• Absolute Pressure Atmospheric plus Hydrostatic.
• Gauge Pressure minus Atmospheric Pressure.
• Density weight per unit volume.
• Fahrenheit to Rankine 460 R
• Boyles Law of Pressure and Volume.
• Charles Law of Temperature and Volume.
• Gay-Lussacs Law of Pressure and Temperature.
• Dalton's Law of Partial Pressures.

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KEY POINTS

• Henrys Law of Dissolved Gases.
• General Gas Law or Ideal Gas Law.
• Archimedes Principle of Buoyancy.
• Surface Air Consumption, in psi per minute.

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QUIZ

• Sound travels _____ times ______ in water than in
  air.
• 2. Objects appear _____ closer and _____ larger
  underwater.
• 3. What is the atmospheric pressure at sea level?
• 14.7 psi.
• What is absolute pressure?
• __________ __________ Atma
• Density is defined as _________ per unit volume.
• One cubic foot of fresh water is equal to ______
  lbs. ffw.
• If a diver descends to 92 feet in seawater what
  is their absolute pressure? ______________________
  ___

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faster
25
33
Atmospheric
Hydrostatic
Weight
62.4
55.64 psi or 3.79 ata
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QUIZ

• A diver has a SAC Rate of 30 psi. per minute. How
  long will their air last at 72 feet in seawater?
  (show all work).
• First Assume, Aluminum 80 _at_ 3000 psi.
• 3000 psi 500 psi (reserve) 2500 psi.
• 2500 psi 30 psi 83.33 minutes at the
  surface.
• Atma
• (SACR) 30 psi x (Depth in Atma) 3.18 Atma
  DACR
• DACR 30 psi x 3.18 Atma 95.4 psi per
  minute.
• 2500 psi 95.4 psi 26.2 minutes at depth.

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OPEN WATER DIVE TRAINING
LBFD
Stan Jackson UICC 5303