The Varying Permeability Model, Variable Permeability Model or VPM is an
algorithm that is used to calculate the
decompression stops needed for ambient pressure
dive profiles using specified
breathing gases. It was developed by D.E. Yount and others for use in
professional diving and
recreational diving. It was developed to model laboratory observations of bubble formation and growth in both inanimate and
in vivo systems exposed to pressure.
In 1986, this model was applied by researchers at the
University of Hawaii to calculate diving
decompression tables.
Theoretical basis
The VPM presumes that microscopic bubble nuclei always exist in water and tissues that contain water. Any nuclei larger than a specific "critical" size, which is related to the maximum dive depth (exposure
pressure), will grow upon decompression when the diver ascends. The VPM aims to minimize the total volume of these growing bubbles by keeping the external pressure large, and the inspired inert gas partial pressures low during decompression. The model depends on the assumptions that different sizes of bubbles exist within the body; that the larger bubbles require less reduction in pressure to begin to grow than smaller ones; and that fewer large bubbles exist than smaller ones. These are used to construct an algorithm that provides decompression schedules designed to allow the larger, growing bubbles to be eliminated before they can cause problems.
Bibliography
This bibliography list was compiled by E.B. Maiken and E.C. Baker as reference material for the V-Planner web site in 2002.
Primary Modeling Sources
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VPM Research and Development Sources
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* Kunkle, T.D. 1979. Bubble nucleation in supersaturated fluids. Univ. of Hawaii
Sea Grant Technical Repor
UNIHI-SEAGRANT-TR-80-01 Pp. 108.
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* Yount, D.E. 1979. Multiple inert-gas bubble disease: a review of the theory. In: Lambertsen, C.J. and Bornmann, R.C. eds. .
Undersea Medical Society, Bethesda, 90-125.
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VPM Dive Planning Software
* V-Planner: VPM-B & VPM-B/E, VPM-B/FBO.
* MultiDeco: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-B, ZHL-C, GF, and GFS.
* Ultimate Planner: VPM-B, VPM-B/U, VPM-B (Dec-12), VPM-B/U (Dec-12), ZHL-B, ZHL-C, ZHL-D, GF and GF/U.
* DecoPlanner: VPM-B.
* HLPlanner: VPM-B.
* JDeco: VPM-B.
* PalmVPM: VPM.
* DivePlan: VPM.
* Baltic Deco Planner: VPM-B.
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Subsurface
In geology, bedrock is solid rock that lies under loose material (regolith) within the crust of Earth or another terrestrial planet.
Definition
Bedrock is the solid rock that underlies looser surface material. An exposed portion of bedro ...
: VPM-B.
VPM Dive computers
* V-Planner Live: VPM-B & VPM-B/E.
* MultiDeco-X1: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.
* MultiDeco-DR5: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.
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Shearwater Research
Shearwater Research is a Canadian manufacturer of dive computers and rebreather electronics for technical diving.
History
In 2004, Shearwater Research was founded by Bruce Partridge who produced their products in a spare bedroom at his home. A ...
Predator, Petrel, Perdix and NERD models: GF, VPM-B plus GFS.
* RATIO Computers: iX3M series and iDive (Tech and Reb) series VPM-B and ZHL16-B.
* TDC-3 with MultiDeco-TDC: VPM-B & VPM-B/E, VPM-B/FBO, ZHL-C, GF, and GFS.
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HeinrichsWeikamp
HeinrichsWeikamp, based in Germany, is a company that produces sports precision instruments for scuba diving including personal dive computers and oxygen partial pressure monitors for diving rebreathers.
Their products: OSTC, OSTC Mk.2, OSTC 2N, ...
OSTC4: VPM-B
See also
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References
External links
VPM web site
{{authority control
Decompression algorithms