SUUNTO HELO2 - Manual (Page 103)

Suunto Technical RGBM model is a modified version of the M-value model. Calculation
of the M-value model can be found in common dive literature. Modifications have been
made to have the model follow RGBM theory as closely as possible. The modifications
have been conducted with the help of Dr. Bruce Wienke. Functionality of Suunto
Technical RGBM has been validated and verified to the depth of 120 m/393 ft with
hundreds of test dives both in the field and in laboratory. The algorithm should not be
used in deeper depths than the verified depth.
Suunto technical algorithm models the human body by using nine tissue groups. In
theory the model is accurate if there are more tissue groups, but using more than nine
tissue groups has no practical significance.
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.
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