Technical
Diving
Frequently Asked Questions
(FAQ's) on Technical Diving.
NOTE: THIS IS NOT TRAINING
MATERIAL AND MUST BE CONSIDERED FOR INFORMATIONAL PURPOSES ONLY.
What is technical diving?
Technical diving is
the use of advanced and specialized equipment and techniques
to enable the diver to gain access to depth, dive time, and
specific underwater environments more safely than might
otherwise be possible.
What does it involve?
First you must
understand the basics, beginning from safety. Safe divers are
divers who take themselves seriously. Accepting that no-one
can learn everything at once, or learn it just from books.
Developing skills slowly, over years a bit at a time and that
is what makes a good technical diver too. You have to ask
yourself some questions. Why do you want
to develope your diving skills? What are your prepared to
sacrifice? How much are you prepared to learn? How long are
you prepared to spend learning.? If the
answer to these questions is something like
Because I
want to go deeper and find more brass....
then it is not the
sport for you. But if the answer is something like
Because I
want my diving to be safer and my bounderies to be
stretched...
Then you are on the
right track. Technical diving, whether it's using nitrox or
other gas mixtures to increase depth or bottom time or
developing sage solo diving or deep diving techniques, is
potentially dangerous as letting an untrained driver loose in
a Formula One car. Before you are considered sage to go out
on the track there is a great deal to learn, and you should
never stop being prepared to learn, never assume you know it
all. You never will. And before stretching your underwater
horizons further, you must first learn to cope with yourself.
What is Nitrox?
Nitrox is a mixture
of oxygen and nitrogen at required level depending on the
type of dive involved. Air is considered to be a nitrox mix.
Nitrox mixes which are hyperoxic (contain more than 21%
oxygen) are variosly known as; enriched air, enriched air
nitrox(EAN or EANx) or SafeAir®.
For most of the part, sport divers will only be interested in
hyperoxic nitrox mixes.
SafeAir® is
copyright of ANDI and refers to any nitrox mix with an oxygen
percentage between 22% and 50%.
How can nitrox be used?
It can be used as a
gas for a normal dive, it can be used for decompression or it
can be travel mix.
- Using it as if
you are using AIR
In this way you are increasing the safety margin
extensively, because by increasing the oxygen level
you can reduce the ongasing effect of the NITROGEN,
thus increasing your bottom time. It
is important to know that the higher is not always
the better. WHY? Because the
more you increase the percentage of oxygen in your
mix the shallower the dive must be because you are
increasing your partial pressure of oxygen which can
result in an oxygen hit.
- Decompression
GAS
If the percentage of oxygen is in the region >40 %
than it can be used as a decompression gas. It is
safer to use it as a decompression gas because it
flashes the nitrogen faster. Remember That
in an emergency 100% oxygen is used and you must know
why.
- Travel Mix
This system is used when you are carrying more than
one cylinder one with a mixture of the bottom and one
to be used while traveling to the bottom. You will
find more information on travel mix later on.
Which are the gases in AIR?
We have 20 %
oxygen, 79 % Nitrogen and 1 % other gases.
What does partial pressure of
Oxygen mean?
The partial
pressure of a gas is the pressure of any gas at depth. The
limits of oxygen toxicity at depth is of 1.6. That means that
you cannot use Air at a greater depth than 66 meters. So if
you are using 31% mix all you do to know the Maximum
Operating Depth (MOD) is 1.6 divide by 0.32 = 5 - 1 = 4 BAR
which is equal to 30 meters. Not difficult isn't it.
Is Nitrox used to do dives of
70m+ ?
No It is not ideal
to do these type of dives. Nitrox is a mixture of higher
partial pressure of oxgyen which reduces your maximum
operating depth.
Isn't Nitrox "mixed
gas" for comercial divers only?
Nitrox is not mixed
gas. It is a blend of the same gas that you are breathing
NOW. It is just enriched with a specified percentage of O2
Why do I need to use Nitrox?
Every diver knows
that nitrogen (N2)
causes narcosis at depths greater than 30 meters. It also
enters the blood stream and is then absorbed by all body
tissues. On ascent from depth this can cause decompression
sickness if absorbed in high enough volume. With Nitrox there
is less N2 and
consequently less problems with nitrogen.
Doesn't more oxygen cause
problems?
Training teaches
you how to use the Oxygen Enriched Air with a very
significant safety factor. Using Nitrox of the correct blend,
at 45 meters is in fact, safer, than using air at 30 meters.
What new diving equipment do I
need to dive using NITROX?
No new equipment is
required if the oxygen content is not to exceed 40%. Nitrox
is compatible with existing SCUBA equipment.
What is hydrocarbon free gas?
It is a air which
is filtered to eliminate nearly all traces of oil in the AIR
or mixture.
It is true that once a
cylinder is filled with nitrox it can never be used with air
again?
It should only be
filled with hydrocarbon free gas. Nitrox does not affect the
inside of the cylinder in any way. However a cylinder colour
coded for Nitrox means that the gas inside is oxygen enriched
air. Refilling with air would not be a safe practice unless
the cylinder colour coding is removed.
I heared that nitrox is only
safe to 40 meters ! What if I want to do deep diving?
When you take a
course on nitrox, they will teach you how to select the
optimum oxygen content for your dive depth.
Why would you want to use
nitrox?
In short, the
correct nitrox mix is safer than air for the divers.
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