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 Overview
 Partial pressure blending
Constant flow blending
Membranes
IT College seminars
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| There is no doubt
that the demand for Enriched Air Nitrox is on the rise. The
number of certified Nitrox divers is growing every year and
as a consequence divers are looking for Nitrox services during
their diving vacations and at home.
The result is that many diving operations are now looking
at their options to offer the requested services. However,
lack of technical know-how and insufficient information on
the installation and operational costs make them reluctant
to take this step.
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 Those
centers that did take the step are frequently using their Nitrox
services as a tool for competition. This goes to the extent
that some are offering Nitrox at no extra charge (compared to
air) as a marketing tool to attract these certified Nitrox divers
to their center. Only time can tell if this strategy will hold
in the long run.
The IT College has created a seminar
for those who are looking for the know-how to offer these
services. Technical know-how and the knowledge needed to make
an informed cost-calculation. The seminar is designed to address
the needs of two groups – those who need to install the installation
(the manager of the company) and those who are operating the
system (the instructors and other staff members). For
instructors, this is an important “plus” on their CV.
The seminar helps to
select the right installation and to keep it running safely
for a long time. |
| How is Nitrox made? |
| Of several available techniques,
the diving industry has (for practical and cost reasons) limited
itself mostly to the application of 3 different methods |
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| By far the most wide spread method
is Partial Pressure Blending. There
are two reasons for that: |
Historically, blending services were first introduced for
“technical diving”. This method does not have limitations
regarding the oxygen percentage in the blend – it fits the
needs for “technical diving” activities and rebreather diving.- The initial cost of the installation is low.
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| In this technique the “blend” is
created at its final pressure – either in an air bank or in
the cylinder the customer is diving with. This means that oxygen
is handled at high pressure, which brings rather a few concerns: |
- The compressor needs to produce oxygen compatible air
– the compressor part in the seminar
- Equipment coming in contact with high pressure oxygen
must be cleaned for that purpose – the blender part of the
seminar
- Filling takes a lot of time (for safety reasons a filling
speed of 3 to 5 bar per minute is required) – the cost calculation
part of the seminar
- The system is not suitable for high quantities of Enriched
Air Fills – the cost calculation part of the seminar
- The entire installation must be equipped with safety
features – the blender part of the seminar
- Not all oxygen from the donor cylinder can be used (unless
a booster pump is added) – the blender part and cost calculation
part of the seminar
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| The other 2 methods have one important aspect in common
– the blend is created before passing the high pressure
compressor. This limits these systems to a maximum oxygen
content of 40% - not the ideal for centers offering rebreather
training or “technical diving”, but the systems are better
and safer for the production of higher quantities of EANx. |
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 Constant
Flow blending is a technique in which oxygen is added to the
compressor inlet. Constant Flow blending is relatively cheap
and easy to handle. It can be considered the ideal for operations
filling up to 100 cylinders of Enriched Air per week (provided
breathing grade Oxygen is available in the area). Some considerations:
- The mix must be completely homogenous before entering
the high pressure compressor – the compressor part of the
seminar
- The compressor must be compatible for mixes up to 40%
oxygen – the compressor part of the seminar
- The system can be adapted for Trimix blends – the blender
part of the seminar
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 Membranes
are ideal for remote area’s, where breathing grade oxygen is
not readily available or would involve high transport cost.
It also should be taken in consideration for a filling volume
of more than 100 Enriched Air cylinders per week – under that
the initial investment would prove high in relation to the return
on investment. In this system a membrane “filters” some of the
Nitrogen from the air, resulting in a blend with a higher Oxygen
percentage to pass trough the high pressure compressor. Some
considerations: |
- The compressor must be compatible for mixes up to 40%
oxygen – the compressor part of the seminar
- The air must pass the membrane under pressure (depending
on the make at a pressure between 3 and 20 bar). There are
two options – banked air is passing a pressure reducer (low
investment – high operational cost) or a low pressure compressor
is added to the system (high investment – lower operational
cost) – cost calculation part of the seminar.
- The membrane is sensitive (and expensive to replace),
so the air must be “very pure” before passing the membrane
to avoid damage. – compressor part of the seminar.
- The output of the membrane must meet the intake of the
compressor to avoid high pressure compressor operational
problems – compressor part of the seminar.
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| Who can teach Enriched Air Diver
Courses |
 In
order to teach Enriched Air Diver courses, you need to be
Enriched Air Specialty Instructor. The IT College offers the
option to do this training either before or after the seminar.
We also have the option to combine this with the Multi Level
Specialty Instructor Course. The decompression theory part
in this program explains details on how tables and dive computers
are calculating, which will allow you to explain Enriched
Air theory with a lot more understanding of the background
and allows you to offer an additional step to extend the dive
time within the no-decompression limit.
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