Mailing List Archive Mailing List Archive
Heres an interesting situation.
As you change to other gases, helium etc etc.
The specific volume of the gas determines the appropiate half life of the
gas in question. This specific half life help detemine the decompression
requirements of the dive for specific tissues. So using the bulman ZHL-16
model and the appropiate adjustment to the a and b values, we can
(we think ) adjust the model to allow use to dive on the other gases.
However these assumptions are based on the fact that these gases act in the
same way as nitrogen in all other aspects, such as solubality.
To an extent they seam too, however as the temperature of the gas carrying
medium decreases so does the solubality. These solubality curves for the
specific gases are not very similar to that of nitrogen.
Also as when we dive the extremities get cold, well colder than the core,
the core being where the gas is diffused into the blood stream the
suggestion is that as the cores gas loaded blood is swept towards the
body extremities, it could give up or off gas some of the gas due to a drop
in solubality with a corresponding drop in pressure. This could lead to an
increase in micro bubble formation in the extremities and hece a
coagulation of the bubbles as they recongerate in the venious side.
I hear you say but the blood go into the core again and warms up bubble
dissappears again, afraid not it now has surface tension and a definate
structure and will not reabsorbe into the system, in fact the raise in
temperature may cause the bubble to expand.
Hence should the a and b factors of the bulman ZHL-16 tables for skin
and extremities tissue not be changed to take this into account.
Are they in the new generation of dive table generators
eg MIG
Abyss
Proplanner
etc etc
If so how and how do you take into effect the differing gases, what research
has been done on this
It could be an explination of why so many of us get headaches and mild
skin bend on deep cold dives
What do the makers of the proparity tables have to say on this subject.
Tom
Tom
*************************************************************************
_/_/_/ _/_/_/ _/_/_/_/ tow@uk*.ac*.nb*.ua*
_/ _/ _/ _/ _/ _/ PROUDMAN OCEANOGRAPHIC LABORATORY
_/ _/ _/ _/ _/ BIDSTON,MERSEYSIDE
_/ _/_/_/ _/ _/ ENGLAND. L43 7RA
I have to go down to the sea again, to the call of the running tide
Tis a wild call but a clear call, that cannot be denied.
**************************************************************************
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]