Divers can choose from a variety of decompression tables. These decompression tables include the Air Table, and Hempleman’s. Both tables have their own benefits and drawbacks. These tables must be used with care.
Air Table decompression tables
The 1930's saw the development of decompression table standards. This was when the Naval Experimental Diving Unit created the first tables that were standardized on a theory. According to this theory, the human body can eliminate nitrogen in a linear manner rather than at an exponential pace. As a result, decompression tables were developed to accommodate this theory and help divers stay safe underwater.
Original diving professionals used "per compartment" accounting as a method to determine nitrogen contents. This compares the different compartment gases to an M-values matrix. These values are sometimes called "half-times" by diving practitioners. However, it is important that these numbers are not real entities and only mathematical expressions. This method is conservative in the short-term and may not be correct for deep, long dives.
Hempleman's decompression 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." His research on decompression tables helped a man survive for ten hours at a depth equivalent to 1,535 feet.
Hempleman updated his tables in 1968 and added a variable ratio between tissue nitrogen tension and ambient pressure. Although he was initially unsuccessful in getting the Navy to adopt his new tables, he made modifications based upon his diving experience. The updated tables were finally adopted by the Navy in 1972.
Hempleman's revised decompression tables
Hempleman's 1968 revised decompression table for diving was published. These tables provide a variable ratio in tissue nitrogen tension to ambientpressure. These results were not appreciated by the Navy at first. Hempleman made modifications to the tables for practical reasons and the Navy adopted the new tables in 1972.
In 1908, Haldane published the first table that was based on his model. In 1908, Haldane published the first known diving tables. He was an adventurous self-experimenter. His experimental studies included animal experiments and the first decompression table for the British Admiralty. Haldane's recommendations were widely used as a clinical endpoint for decompression sickness.
Hempleman's modified depression 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. Hempleman decided to alter the tables for practical purposes. Later, these tables were reproduced in metric units. They were adopted by U.S. Navy 1972.
The tables were adopted by the British Royal Navy in 1908 and they were used until the 1950s when they were redesigned due to concern that they were 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.