4. -Air pocket over the eye
-Visual distortion
-VF restriction
-Pressure
- Volume changes with
attendant discomfort
- irritation from chemical
or bacteriologic sources.
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8. -Hypoallergenic silicone
skirts and straps
are more comfortable,
cause less irritation
of the skin and eyes, and
are significantly longerlasting than natural
rubber products.
-Black algae and other
organisms can grow
easily.
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9. -Lenses with the
appropriate corrections
can be placed in masks
quite easily and
offer an alternative to
contact lenses and
eyeglasses
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10. Fluid Dynamics of Swimming
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12. 10/31/ژانويه
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The longer, narrower fins
tended to be slightly more
efficient than the
shorter, wider fins and
that fins with vents,
regardless of their
direction, were not
superior to those without
vents.
- The split-blade over the
solid-blade fins
12
13. A wider, slower kick
is more efficient than the
rapid, shallow kick
often used by novice
divers.
-Flutter kick
-Sculling-type kick
- Different functional
muscle groups(to
prevent fatigue)
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14. 10/31/ژانويه
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-Snorkel tubes, used for
easier breathing
while swimming on the
surface, have evolved
from simple tubes that
are open at both ends
to devices that offer
purge valves, swivel
mouthpieces, advanced
materials, and mouthpieces of improved design
14
15. -Long snorkels increase
physiologic dead space
and can lead to CO2
retention and
hypercarbia.
Excessively long
snorkels should be
avoided.
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15
16. The snorkel mouthpiece
should be able to
rotate on the snorkel tube
so that the lip flange of
the mouthpiece can be
placed parallel to the
teeth and gums.
Blisters of the oral
mucosa and T.M joint
problems can result
from poor alignment.
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16
17. -The scuba, or self-contained
underwater breathing
apparatus, used by
recreational, scientific,
commercial, and
military divers.
-Permits divers to move
independently under water
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18. 10/31/ژانويه
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-Constructed
of steel or aluminum, but
stainless steel and
titanium are also used.
-Inspected annually by a trained
inspector
-Hydrostatic test procedure that
is required every 5 y
-Volume:50-120 ft*3
-Do not breathe the cylinder
pressure < 200 psi except in
18
an emergency
19. Advantage:dec pre-res gasabeh.com
work
Disadvantage:ignor dec pre of tunk
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-Inhalation and exhalation
resistance of less than 3
inches (7.5 cm) of water
-First stage of the regulator,
where its pressure is reduced
to an intermediate
pressure of 130 to 150 psi.
-Sconed stage of the regulator,
where its pressure is reduced
to the pressure of the
surrounding environment
and the diver’s lungs
19
20. Advantage:dec weight-not bubbleDisadvantage:hi expens-traini-low fswgasabeh.com
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o2 toxi
-Closed-circuit breathing
apparatus consists of a
mouthpiece and hoses
connected to a breathing bag,
a carbon dioxide–absorbent
canister, and a highpressure breathing gas
supply.
-Sensor-controlled rebreather
devices are typically set to
hold the oxygen partial
pressure between 0.5 -0.7
20
atm.
21. gasabeh.com
is not a life jacket
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- The buoyancy compensator
is used as a tool whose
primary function is to
maintain the diver in a nearneutral state at any depth
while maintaining a desired
position, usually face down.
-To accomplish this,
the device should concentrate
much of the flotation near
the center of mass of the
body.
21
22. PERSONAL FLOTATION DEVICES
Life jacket
buoyancy control device:
-an automatic inflation
-risk of confusion
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load-bearing jacket
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22
23. -One liter of air displaces 1.03
kg of seawater (2.3 lb);
thus, a buoyancy bladder
exerts 2.3 lb of lifting force
for every liter of water
displaced.
-Smaller buoyancy
compensators have a capacity of approximately 10 L,
whereas larger devices often
have a capacity of 20 L or
more.
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24. Fluid Dynamics of Swimming
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26. - Drag develops in three
basic ways during
diving: by frontal
resistance, by skin
friction,and by turbulent
or eddy resistance. Drag
is the sum of these three
types of resistance.
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26
28. - When a diver
enters water with a heat
conduction capacity
25 times that of air, heat
is conducted from
the body and adaptive
changes occur to
protect the body from a
fall in core temperature.
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28
29. - The most common
protective garment is
the wet suit , which uses a
layer of air-impregnated
neoprene rubber as the
insulating boundary to trap
water next to the
diver’s skin as an insulating
layer. A well fitted wet suit
holds the water in place so
that heat is not exchanged by
water displacement.
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30. - Dry suits have become more
popular in
recent years because of
improvements in fit
and mobility. Comfortable
insulating
undergarments, effective
valve mechanisms, and
better seals have also been
added.
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control
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31. 10/31/ژانويه
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-These dive computers
monitor pressure and time;
they then provide
information that can guide the
diver through a
proper decompression.
-Computers are not riskFree.-Because there are no
“safe” tables or “safe” dive
computers,every diver must
accept some risk when
diving for sport or occupation.
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32. -Dive computers cannot
guarantee that their use will
preventdecompression
sickness. Properly used,
these devices should
reduce the risk under
normal circumstances.
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