SUUNTO D9tx - Manual (Page 122)

Tissue calculation aims to model the amount of nitrogen (N
2
) and helium (He) saturated
in tissues. Ongasing and offgasing of saturated gas is modelled using the ideal gas
equation. In practice this means that the total pressure of the nitrogen and helium tis-
sues can be higher than the total pressure of the breathing gas, even without any ex-
posure to pressure. For example, when a diver dives an air dive soon after a demanding
trimix dive, the residual pressure of helium combined with a high nitrogen content
cause the diver a decompression obligation very fast.
10.2.2. Diver safety and Suunto Technical RGBM model
Because any decompression model is purely theoretical and does not monitor the
actual body of a diver, no decompression model can guarantee the absence of DCI.
Suunto Technical RGBM model has many features that reduce the risk of DCI. The
Suunto Technical RGBM algorithm adapts its predictions of both the effects of micro-
bubble buildup and adverse dive profiles in the current dive series. The pattern and
speed of decompression is adjusted according to the microbubble influence. The ad-
justment is also applied to the maximum combined nitrogen and helium overpressure
in each theoretical tissue group. To add diver safety, off gassing is also slowed down
compared to on gassing and the amount of slowing down depends on the tissue group.
Experimentally it has been shown that the body adapts to decompression to some
degree when diving is constant and frequent. Two personal adjustment settings (P-1
and P-2) are available for divers who dive constantly and are ready to accept greater
personal risk.
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