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Decompression tables for diving



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Divers have a choice of several types decompression table options. These decompression tables include the Air Table, and Hempleman’s. Both tables have their advantages and disadvantages. These tables should be used with care and a diving guide should always be used in conjunction with the decompression table.

Air Table decompression tables

Decompression tables were developed in the 1930's by the Navy's Naval Experimental Diving Unit. They created the first standardised tables based upon a theory. According to this theory, the human body can eliminate nitrogen in a linear manner rather than at an exponential pace. To accommodate this theory, decompression tables have been created to help divers stay safe and sound underwater.

Initial diving practices used 'per compartment accounting' to determine nitrogen content. This was a conservative approach. This compares the different compartment gases to an M-values matrix. These values are often referred to as 'half times' by diving professionals. However, they can only be mathematical expressions, and not real entities. Air tables that are based on this method tend not to be accurate for long, shallow dives.


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Hempleman’s decompression tables

Val Hempleman's decompression tables helped the Royal Navy stay on the cutting edge of deep diving technology and saved many lives. Hempleman, who was Royal Naval Physiological Laboratory chief from 1968 to 1982 worked to overcome the "bends." His research on decompression tables helped a man survive for ten hours at a depth equivalent to 1,535 feet.


Hempleman changed his tables to include a variable ratio for tissue nitrogen tension and ambient press in 1968. After initially being unable to convince the Navy to adopt the tables, Hempleman made modifications based in his diving experiences. The Navy finally adopted the revised tables in 1972.

Hempleman's revised despression tables

Hempleman released revised decompression tables in 1968 for diving. These tables include a variable ratio of tissue nitrogen tension to ambient pressure. Although initially the Navy didn't like the results, Hempleman modified these tables for practical purposes. In 1972, the Navy adopted the new tables.

The first table based on Haldane's model was published in 1908. Haldane, an avid self-experimenter, published the first officially recognized diving tables in 1908. His experiments included animal experiments as well as the creation of the first British Admiralty decompression table. Haldane’s clinical guidelines were widely adopted as a guideline for decompression sick.


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Hempleman's modified Decompression Tables

Hempleman changed the decompression tables in 1968 so that they included a variable ratio between tissue nitrogen tension and ambient pressure. However, the Navy rejected the changes and refused permission to implement them. This led Hempleman to change the tables for practical purposes. These tables were later reproduced in metric units and were adopted by the U.S. Navy in 1972.

In 1908, the British Royal Navy adopted these tables and used them until the 1950s. They were then revised due to concerns about being too conservative. In the same decade the U.S. Navy used what are now known C andR tables. This practice became popular in the 1980s.



 



Decompression tables for diving