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IV Diving with Microbubble-Level (MB)
IV Uwatec
®
Smart dive computers
The following chapter will deal with the characteristics of diving with microbubble-levels (MB-
level). For general information about displays and features of diving with Smart see chapter III.
Microbubbles
are tiny bubbles that can build up inside a diver's body during any dive and normally dissi-
pate naturally during an ascent and on the surface after a dive. Dives within no-stop time and observance of
decompression stops does not prevent the formation of microbubbles in the venous blood circulation.
Dangerous microbubbles are those migrating into in the arterial circulation. The reasons for the migration
from the venous blood circulation to the arterial circulation can be a great many bubbles collecting in the
lungs or if a diver suffers from PFO (patent foramen ovale), an open connection between the right and left
atrium of the heart.
With Smart Uwatec has developed a new technology to keep the formation of microbubbles in check. The
diver chooses – according to his/her needs – an MB-level and influences through it the suppression of micro-
bubbles.
Diving with MB-levels requires additional ascent stops (level-stops), the ascent is slowed and the body gets
more time to desaturate. This works contrary to the formation of the microbubbles and increases the safety.
Smart features
6 microbubble-levels
(L0-L5). Level 0 corresponds with Uwatec's well-known
decompression model ZH-L8 ADT and does not require level-stops due to microbubble formation. Levels L1
to L5 offer additional protection from bubble formation with level 5 offering the highest protection and
should be selected for example by divers suffering from PFO.
Similar to the display of information during decompression dives or dives within no-stop time, Smart dis-
plays depth and duration of the first level-stop as well as the total time of ascent, as soon as the MB no-stop
time has run out. As the MB no-stop time is shorter than the ordinary no-stop time a diver will be required to
carry out a stop (level-stop) sooner than a diver using level 0.
If a diver ignores a required level-stop, Smart will change over to a lower MB-level and the dive can not be
completed with the initially chosen MB-level. E.g. If a diver sets level 4 on the Smart prior to the dive and during
the dive ignores the stops recommended the Smart will automatically adjust the setting to level 3 or lower.
1 Comparison of dives with MB-level 0 and MB-level 5
When two Smarts are used simultaneously, one unit is set on MB-Level L5, the other on L0, whilst diving
with MB-levels L1 to L5 the no-stop time will be shortened and level-stops will be required before the diver
has the obligation of a decompression-stop. These additional level-stops help dissipate the microbubbles.
3m/10ft
6m/20ft
9m/30ft
12m/40ft
15m/50ft
Time
Depth
Micr
obubble-
level
Microbubble accumulation
at the end of dive
Stop depth
L0
L5
L0
L5
m
DECO STOP
m
LEVELSTOP
m
LEVELSTOP
NO STOP
m
LEVELSTOP
NO STOP
NO STOP
NO STOP
DECO
ft
ft
ft
ft
Decompression values
Level Stop values
Decompression obligation, see page 25
Eg-SMART III+IV 13.10.2001 11:16 Uhr Seite 22
