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There is a lot of healty safety oriented discussion on all
TechDiving forums, but it seems that many things are learned by
bad experiences.
Use of full face masks is emerging in technical diving community.
All the articles and comments I have seen all
concentrate on "the lighter side" of using one. A full face mask
will give some added safety against oxygen toxicity and enable
communications.( And of course, they look cool and they are
really expensive ;)
These articles leave in the dark...
"THE DARKER SIDE OF FULL FACE MASKS"
Why to use a full face mask? A full face mask is basically designed
1)To make life simpler for commercial diver (One does not have to
worry about loosing a mouthpiece)
2)To isolate diver from polluted water (Safety pressure a big +)
3)To isolate diver from cold water
These are not primary problems for a sport diver nor in most
cases to a TechDiver. On the contrary a full face mask itself
presents several new difficulties to diver self-sufficiency:
-Freezing: Even as INTERSPIRO is one of the most difficult
second stages to freeze (I have understood that EXO freezes
easily) it can freeze in cold water and large gas flow
especially if water from previous dives or rinses have
penetrated to inhalation side of the system.
In this situation one might switch off the air and operate air
manually at the same time breathing slowly. This is unsatisfactory
arrangement.
-Equipment redundancy: change to another second stage requires taking
off the full face, swithing to a mouthpiece and emptying a mask.
This is unsatisfactory arrangement.
Theoretically one can use a quick-disconnect plug to move to another
first stage in case of first stage malfunction. This too is an
unsatisfactory arrangement.
-Surface problems: If one has to take off the mask on surface
even a short swim completely without a mask is difficult.
-Gas switching: Gas switch is possible with full face with
a change-block, but...
Simplest and safest arrangement for gas switch or a emergency
switch is using set of normal mouthpieces all the time. I can
see practical use of Full faces limited to high pO2 decos and
cold water diving.
I have a long list of "close-calls" related to use of full face
masks (We have used these for quite some time).
I hope other people would not have to "field test" to prove the
above arguments as was the case in "Surface crew and safety diver
in TechDiving".
(I use an Interspiro all the time. Water is cold in Baltic sea.)
Safe dives!
Reima Raty
Nordic CMAS ***
FINLAND
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