Divers have a choice of several types decompression table options. Two such tables are the Hempleman's and Air Table decompression table. Both tables have their advantages and disadvantages. These tables should be handled with care. Always use a dive guide 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. The theory suggested that nitrogen can be eliminated in a linear fashion by the human body, and not at an exponential rate. Decompression tables were created to support this theory and ensure that divers are safe underwater.
In the beginning, divers used 'per-compartment' accounting to determine nitrogen content. This method compares the various compartment gases to a matrix called M-values. These values are often referred to as 'half times' by diving professionals. However, they can only be mathematical expressions, and not real entities. These air tables are conservative for short-term dives and can be inaccurate for shallower, longer dives.
Hempleman's despression tables
Val Hempleman's deep diving tables saved many lives and helped the Royal Navy remain at the forefront of deep diving technology. Hempleman's tenure as the Royal Naval Physiological Laboratory Superintendent from 1968 to82 saw him work to overcome "the bends." Hempleman's research into decompression tables enabled a man to survive for ten hour at a depth equivalent of 1,535 feet.
In 1968, Hempleman revised his tables and included a variable ratio of tissue nitrogen tension to ambient pressure. After initially being unable to convince the Navy to adopt the tables, Hempleman made modifications based in his diving experiences. In 1972, the Navy adopted the updated tables.
Hempleman's revised decompression tables
In 1968, Hempleman published revised decompression tables for diving. These tables show a variable ratio for tissue nitrogen tension to ambient air pressure. These results were initially not liked by the Navy. However, Hempleman modified them for practical purposes. The Navy adopted the new tables in 1972.
The first table based on Haldane's model was published in 1908. Haldane was an independent experimenter who published the first diving tables in 1908. His experiments included animal research and the development of the first British Admiralty-approved decompression table. Haldane’s clinical guidelines were widely adopted as a guideline for decompression sick.
Hempleman's modified decompression tables
Hempleman revised decompression charts in 1968 to incorporate a variable ratio for tissue nitrogen tension and ambient press. The Navy opposed the changes and refused implementation of the tables. Hempleman had to amend the tables for practical use. Later, these tables were reprinted in metric units and adopted by the U.S. Navy on February 2, 1972.
The British Royal Navy adopted the tables back in 1908 and used them until 1950s. In the same decade the U.S. Navy used what are now known C andR tables. This practice became popular in the 1980s.