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Dr.Dr. HasrizalHasrizal ShaariShaari

 

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 arac er s cs o r an a er.

Buoyancy.  What is Pressure?

  . The Anatomy of Your Lungs.

Indirect Effects of Pressure.

  .

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.

The gases in air are colorless,odorless and tasteless.

r s compose o approx ma e y .oxygen, 78% nitrogen and 1.1%

miscellaneous gases.

oxygen.

trogen s meta o ca y nert.

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The main h sical stress of the underwater  The effect of hydrostatic pressure

Seawater is slightly dense than freshwater 

The fraction of seawater concentration

therefore 96.5% H2O and 3.5% salts.

This characteristic  Buoyancy

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In the Water 

Water affects our vision, hearing, ability to

.

.

- Objects appear 1/3 closer and larger under

water.

ii. Colors

- .

iii. Heat loss

-

iv. Drag

- .

resistance is called drag.

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The rinci le of buo anc In science, buoyancy is an upward force exerted by a fluid that

opposes the weight of an immersed object. In a column of fluid,

pressure increases with depth as a result of the weight of the

overlying fluid.

Archimedes’ principle, physical law of buoyancy,

An ob ect wholl or artiall immersed in a fluid is buo ed u b a

force equal to the weight of the fluid displaced by the object.

Buoyancy = weight of displaced fluid.When object immersed in a fluid = buoyant

force equal to the weight

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States of Buo anc Positive buoyancy If an object floats, it means the object

dis laces an amount of water that wei hs more than the

object does

Neutral buoyancy If an object hovers, it means the object

displaces an amount of water that weighs same as the object

does.

buoyancy If an

object sinks, it means

an amount of water

that weighs less than

t e o ject oes.

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your body and gear you wear.

  ,

thickness of your suit, and your gear.

Human body like “bag of water” reffered toliquid-solid compartment of body.

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  BCD Buo anc Control Device

Lead Weight

  ung vo ume

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The density of the water in which you dive

also affects your buoyancy.

If you are weighted to be neutral in salt water and you

dive in fresh water with the same amount of weight, you

 

.

eu ra uoyancy enea e sur ace:

It is important to help protect marine life.

Diving without buoyancy control:

Is tiring, hazardous, and a sign of an unskilled, unthinking,

and uncaring diver.

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 What is Pressure?

This force is called pressure and is measured

in bar or ounds er s uare inch si

If you weighed a column of air that extended all

the way to the edge of the atmosphere:

1 inch by 1 inch = 14.7 psi

1 centimeter b 1 centimeter = 1 kilo ram

This constant pressure is called 1 atmosphereof pressure.

 As long as the pressure in a body’s air spaces

matches the surrounding atmospheric pressure,the pressure is equalized and you do not feel any

effects from your surrounding atmospheric

.

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 ,

consider the effects of pressure on an open and

closed s stem.

The pressure surroundingthe bucket increases and

bucket.

The inverse relationship

volume is known as Boyle’sLaw

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How Pressure Affects VolumeHow Pressure Affects Volume

The effects of pressure on a closed system can be muchmore dramatic.

The bag becomes smaller and smaller as the air  

compresses and the volume decreases.

You must NEVER hold your breath when breathingcompressed air under water.

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   When you descend in water, the force from the

 weight of the air and the water above affects you.

Boyle’s Law

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How Pressure Affects DensitHow Pressure Affects Densit

You use your air faster when you dive deeper.

As the pressure ↑, the air compresses to

As the air compresses, it becomes denser.

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Pressure and Air Consum tionPressure and Air Consum tionThe rate at which you consume the air in your cylinder isdirectly proportional to the depth you dive.

 Air consumption factors:

 Your activity level during your dive Your mental state.

 Your body size.

e warm o your v ng su .

 Your level of physical fitness.

  .

 You can use up 4x air as much as air exerting than when

resting.Develop a slow and relaxed breathing pattern as well as aslow rate of breathing.

arger peop e ave arger ungs an use more a r an

smaller people

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  When you dive, the pressure of the water

effects your air spaces as well as your breathing.

Squeezes:

Whenever the pressure outside an air space

lungs

is greater than the pressure inside an airspace.

 s type o n ury s ca e arotrauma

(pressure injury).

A reverse block is the opposite of amiddle ears

.

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The Middle Ear You must be able to equalize the pressure inside your ears tocomfortably and safely dive.

Anatomy of the ear:

i. Outer ear e outer ear is t e ear cana

ii. Middle ear

 

Contains the airway link called the eustachian tube.

iii. Inner ear

Contains the balance mechanism.

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in your outer ear is greater than the air 

.

Equalizing your middle ear:

 your ears, you need to equalize.

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  Never force equalizing your ears. You

could cause serious damage to your ears.

The ke to successful ear e ualization:equalize early and often

 

Ascend a few feet to reduce the pressure, and

a emp o equa ze aga n.

If you have a head cold, you must notattempt to equalize by any method.

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your ear hurts and feels

“ ”,

descend until the feeling

.

If the block does not

equa ze:

If you must surface, close yournose and mouth and breathe in.

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mucous membranes and surrounded by

.

Sinus squeeze and blockage: Never dive when you have

a cold or sinus congestion.

Decongestant drugs:

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Teeth: Mask space:

 

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air sacs, called alveoli. Lung over-expansion injuries:

 

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Breathin and CirculationBreathin and Circulation

 is a vital function of the circulatory

system.

Carbon dioxide controls your breathing.

  .

Shallow breathing:  ,

not exchange enough air with each

breath.

Hyperventilation:

Deliberately breathing deeply and rapidly

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  Ski breathin :

When a diver slip breathes, they hold each breath for anextended period of time rather than breathing normally.

, -carbon dioxide in the body.

r tarvat on:

Regulators have a limit as to how much air they can give you.

If you feel starved for air, and you feel that your regulator isnot supplying you with the amount of air you need:

Stop what you are doing, rest, and breathe slowly anddeeply until you recover, being sure to exhale fully witheac rea .

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  Ingassing and offgassing:• 78% of the air we breathe is N.

• N is an inert gas, but is absorbed andtissues.

• The ressure of N is balanced

between the air and your body. Thisstate is called equilibrium.

,you breathe is denser and than the

partial pressure N you inhale witheach breath is increased.

• With changes in the ambient

offgasses until the N is balancedbetween air and your body.

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 " " " “ . 

bubbles blocking circulation in the small veins of 

oints elbows, knees, shoulders cause ain that adiver may seek to relieve by bending those joints.

Even very experienced divers can get bent, so dotake this very, very seriously.

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It takes time for N to enter and to leave the body. –  When you ascend your body begins to eliminate N.

 –  If too much is still present after you surface, the

excess N forms bubbles in your body.

When bubbles form in your blood, they can create

m croscop c c o s a mpa r your c rcu a on.

 –  Symptoms of DCS can range from skin rash, extreme

,

unconsciousness.

Prevention:

 

 Ascent Rate

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DCS T esDCS T es

 

less severe and may manifest itself as

,sometimes fatigue and vertigo.

Type II DCS  more serious neuralgic,

blood flow can result in weakness,

, , ,sensations, personality change and

.

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Treatment:Treatment:

First aid in mild cases is 100% oxygen,

,

thinner, and plenty of rest.

chamber, and the faster the better. That way, the bubblesdissolve a ain and are ro erl and slowl eliminated

through slow recompression.

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Precaution of DCSPrecaution of DCS

Ascend slowly to allow plenty of time for the

o ou -gas

Make a one minute stop at half yourmaximum dive depth

Make a 3-5 minute safety stop at 15 feet

Always do the deepest dive first  

Allow extra surface interval time between

Allow 12 to 24 hours before you fly in an

a rp ane a er v ng

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Carbon Monoxide ToxicitCarbon Monoxide Toxicit

CO is an odorless tasteless as comin from the

combustion of organic matter.

It combines with blood, hemoglobin really, much

more easily than oxygen, some 200x more readily in

fact.

CO poisoning can happen if a faulty or poorly

maintained air compressor adds CO into the tank 

or suc s n a rea y con am na e a r.

mo ers a rea y n a e an at greater r s or  

hypoxicity (being low on O2).

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 .

, ,

the diver inhales many more CO molecules,

enou h for oisonin s m tons such as headaches

confusion, tunnel vision and worse.

Treatment  pure O2 and fresh air.

Serious cases   recompression in a chamber with

100% O2 may bee necessary to reduce, or  

eliminate, longterm damage.

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Nitro en NarcosisNitro en Narcosis

Narcosis also known as:

.

ii. Inert gas narcosis

iii. Ra tures of the deeiv. Martini effect

Reversible alteration in consciousness that occurs while diving at depth.

partial pressure.

The deeper a diver descends, the higher the partialpressure of N and other gasses in his air will be. For this

function of depth. The deeper a diver goes, the greater the narcosis.

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 .

Breathing cold compressed air from a cylinder.

 

If the air containing the water vapor is cooled, the water

.

When water condenses on the lens of a mask, it formsbeads of water. fo in 

Having to humidify the air we breathe causes dehydration.

 capacity and makes you more susceptible to DCS.

You must drink lent of fluids before between and after

dives.

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