Divers can choose from a variety of decompression tables. Two such tables are the Hempleman's and Air Table decompression table. Both tables have their own benefits and drawbacks. 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. This theory stated that the human body is able to eliminate nitrogen in a linear fashion, rather than at an exponential rate. To accommodate this theory, decompression tables have been created to help divers stay safe and sound 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. The air tables based upon this method are generally conservative and may not work well for long, shallow dives.
Hempleman's despression tables
Val Hempleman’s decompression tables were a lifesaver for many people. During his tenure as Royal Naval Physiological Laboratory superintendent from 1968 to 1982, Hempleman worked to overcome "the bends." His research on the decompression tables was instrumental in helping a man survive for ten consecutive hours at a depth of 1.535 feet.
Hempleman modified his tables and added a variable proportion of tissue nitrogen tension to ambient. This was done in 1968. He was initially unable to get the Navy to adopt the new tables, but made modifications based on his practical diving experience. The Navy adopted the new tables in 1972.
Hempleman's revised Decompression Tables
Hempleman released revised decompression tables in 1968 for diving. These tables show a variable ratio for tissue nitrogen tension to ambient air pressure. Although the Navy initially did not like these results, Hempleman modified the tables for practical purposes and the new tables were eventually adopted by the Navy 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 experimental work included animal experiments and the publication of the first British Admiralty dive table. Haldane's recommendations were widely used as a clinical endpoint for decompression sickness.
Hempleman's modified compression tables
Hempleman changed the decompression tables in 1968 so that they included a variable ratio between tissue nitrogen tension and ambient pressure. The Navy was not happy with the proposed changes and refused to allow them to be implemented. Hempleman decided to alter the tables for practical purposes. These tables were later reprinted using metric units, and adopted by U.S. Navy in 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, U.S. Navy adopted what are now called C- and R tables. This practice became widespread in the 1980s.