Uwatec Aladin A1, User Manual

Page: 47 / 64

47
English
A1 USER MANUAL
PDIS Profile 1 PDIS Profile 2
SAFETY STOP
PDI STOP
Dive Profile 1
Dive Profile 2
Deep Stop
40m
30m
20m
10m
8min 16min 24min 32min 40min 48min
DIVE TIME
DEPTH
4.8.2 How does PDIS work?
The mathematical decompression model
in the A1, called ZH-L16 ADT MB, tracks
your decompression status by dividing
your body into 16 so-called compartments
and mathematically following the uptake
and release of nitrogen in each with the
appropriate laws of physics. The various
compartments simulate parts of your body
such as central nervous system, muscles,
bones, skin and so on.
The depth of the PDI stop is calculated as
that at which the leading compartment for
the decompression calculation switches
from on-gassing to off-gassing, and the
diver is advised to perform a 2-minute
stop above the displayed depth (this is the
opposite of a decompression stop, where
you are asked to remain just beneath the
displayed depth). During this intermediate
stop, the body is not taking up any more
nitrogen in the leading compartment, but
rather releasing nitrogen (though under
a very small pressure gradient). This,
combined with the relatively high ambient
pressure, inhibits bubble growth. It should
be noted that the 4 fastest compartments,
up to 10-minute half-times, respectively, are
not considered for the determination of the
PDI stop depth. This is due to the fact that
these compartments are only “leading” for
very short dives, for which an intermediate
stop is not required at all.
F
NOTE: The PDI stop is not a mandatory
stop, and it is NOT a substitute for the
3- to 5-minute safety stop at 5m/15ft.
WARNING
Even when performing a PDI stop, you still
MUST perform a safety stop at 5m/15ft for 3
to 5 minutes. Performing a 3- to 5-minute stop
at 5m/15ft at the end of any dive remains the
best thing you can do for yourself.