Divers have many options for decompression tables. The Air Table and Hempleman's decompression tables are two such decompression tables. Both tables have their own benefits and drawbacks. These tables should not be used without 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. This theory was reflected in decompression tables, which were designed to aid divers staying safe underwater.
Original diving professionals used "per compartment" accounting as a method to determine nitrogen contents. This method uses the M-values matrix to compare the various compartment gases. 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, who was Royal Naval Physiological Laboratory chief from 1968 to 1982 worked to overcome the "bends." His research on decompression table helped a man survive ten hours at the depth of 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 Navy finally adopted the revised tables in 1972.
Hempleman's revised table of decompression
Hempleman released revised decompression tables in 1968 for diving. 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.
The first table to be based on Haldane’s model was published by Haldane in 1908. In 1908, Haldane published the first known diving tables. He was an adventurous self-experimenter. His experiments included animal research and the development of the first British Admiralty-approved decompression table. The clinical endpoint of decompression sickness was widely used by Haldane.
Hempleman's modified depression tables
Hempleman updated the decompression table to include a variable rate of tissue nitrogen tension relative to ambient pressure in 1968. However, the Navy refused to approve the changes and refused the tables' implementation. Hempleman decided to alter the tables for practical purposes. 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 in 1908 and continued using them until the 1950s, when they were revised because of concerns that they were too conservative. In the same decade, the U.S. Navy began using what are now known as C and R tables, and this practice became common in the 1980s.