Bühlmann tables
Encyclopedia
The Bühlmann decompression algorithm is a mathematical model (algorithm
) of the way in which inert gases enter and leave the body as the ambient pressure
changes. It is used to create Bühlmann tables. These are decompression tables which allow divers
to plan the depth and duration for dives and show decompression stops when necessary. The algorithm was developed by Dr. Albert A. Bühlmann
, who did research into decompression theory at the Laboratory of Hyperbaric Physiology at the University Hospital in Zürich
, Switzerland
.
The results of Bühlmann's research that began in 1959, was published in a 1983 German book entitled Decompression-Decompression Sickness. The book was regarded as the most complete public reference on decompression calculations and was used soon after in dive computer
algorithms.
, Bühlmann designed studies to establish the longest half-times
of nitrogen and helium. These studies were confirmed by the Capshell experiments in the Mediterranean sea
in 1966.
The naming convention he used to describe his algorithms, for example, ZH-L16, comes from Zürich (ZH), limits (L) and the number of tissue compartments or M-value sets used (16).
Bühlmann System was developed by Bob Cole. This system used the dive tables and a set of rules so that people could dive safely and stay below their no-decompression limit. The tables are still used today and are very popular; many dive computers still use the ZHL-8 algorithm and many tables are based on the ZHL-16 algorithm. These calculations also include considerations for repetitive and altitude diving
.
Many articles on the Bühlmann tables are available on the web. An example of an overview of the history of Bühlmann tables may be found at Decompression Theory: Robert Workman and Prof A Bühlmann. DIY DECOMPRESSION works through the steps involved in using the algorithm to write a decompression program.
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
) of the way in which inert gases enter and leave the body as the ambient pressure
Ambient pressure
The ambient pressure on an object is the pressure of the surrounding medium, such as a gas or liquid, which comes into contact with the object....
changes. It is used to create Bühlmann tables. These are decompression tables which allow divers
Underwater diving
Underwater diving is the practice of going underwater, either with breathing apparatus or by breath-holding .Recreational diving is a popular activity...
to plan the depth and duration for dives and show decompression stops when necessary. The algorithm was developed by Dr. Albert A. Bühlmann
Albert A. Bühlmann
Professor Albert A. Bühlmann was a Swiss physician who was principally responsible for a number of important contributions to decompression science at the Laboratory of Hyperbaric Physiology at the University Hospital in Zürich, Switzerland. His impact on diving ranged from complex commercial and...
, who did research into decompression theory at the Laboratory of Hyperbaric Physiology at the University Hospital in Zürich
Zürich
Zurich is the largest city in Switzerland and the capital of the canton of Zurich. It is located in central Switzerland at the northwestern tip of Lake Zurich...
, Switzerland
Switzerland
Switzerland name of one of the Swiss cantons. ; ; ; or ), in its full name the Swiss Confederation , is a federal republic consisting of 26 cantons, with Bern as the seat of the federal authorities. The country is situated in Western Europe,Or Central Europe depending on the definition....
.
The results of Bühlmann's research that began in 1959, was published in a 1983 German book entitled Decompression-Decompression Sickness. The book was regarded as the most complete public reference on decompression calculations and was used soon after in dive computer
Dive computer
A dive computer or decompression meter is a device used by a scuba diver to measure the time and depth of a dive so that a safe ascent profile can be calculated and displayed so that the diver can avoid decompression sickness.- Purpose :...
algorithms.
Principles
Building off the previous work of John Scott Haldane and Robert Workman, and working off funding from Shell Oil CompanyShell Oil Company
Shell Oil Company is the United States-based subsidiary of Royal Dutch Shell, a multinational oil company of Anglo Dutch origins, which is amongst the largest oil companies in the world. Approximately 22,000 Shell employees are based in the U.S. The head office in the U.S. is in Houston, Texas...
, Bühlmann designed studies to establish the longest half-times
Half time (physics)
The half time is the time taken by a quantity to reach one half of its final value, where the rate of change is proportional to the difference between the present value and the final value....
of nitrogen and helium. These studies were confirmed by the Capshell experiments in the Mediterranean sea
Mediterranean Sea
The Mediterranean Sea is a sea connected to the Atlantic Ocean surrounded by the Mediterranean region and almost completely enclosed by land: on the north by Anatolia and Europe, on the south by North Africa, and on the east by the Levant...
in 1966.
The naming convention he used to describe his algorithms, for example, ZH-L16, comes from Zürich (ZH), limits (L) and the number of tissue compartments or M-value sets used (16).
Tables
Max Hahn first used Bühlmann's algorithm to develop dive tables for the Swiss Underwater Sport Association. In 1987 the SAASub-Aqua Association
The Sub-Aqua Association or SAA is a diver training organization for scubadivers in the United Kingdom. The association and some other UK-based diving groups have traditionally used a club-based system with unpaid instructors, while the other principal training agency, PADI, organises most of its...
Bühlmann System was developed by Bob Cole. This system used the dive tables and a set of rules so that people could dive safely and stay below their no-decompression limit. The tables are still used today and are very popular; many dive computers still use the ZHL-8 algorithm and many tables are based on the ZHL-16 algorithm. These calculations also include considerations for repetitive and altitude diving
Altitude diving
Altitude diving is scuba diving where the surface is 300 meters or more above sea level . The U.S. Navy tables recommend that no alteration be made for dives at altitudes lower than 91 meters and dives between 91 meters and 300 meters correction is required for dives over 44 meters sea water...
.
Many articles on the Bühlmann tables are available on the web. An example of an overview of the history of Bühlmann tables may be found at Decompression Theory: Robert Workman and Prof A Bühlmann. DIY DECOMPRESSION works through the steps involved in using the algorithm to write a decompression program.