Divers can choose from several different types of decompression plates. Two such tables are the Hempleman's and Air Table decompression table. Both tables have both their 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. This theory said that the human body can remove nitrogen in a linear way, not an exponential manner. Therefore, decompression plates were created to accommodate this theory. They also help divers remain 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 commonly referred to by divers as "half-times", but it is important to remember that they are mathematical expressions and not real entities. Hence, the air tables based on this method tend to be conservative in the short term, and may be incorrect for long, shallow dives.
Hempleman’s decompression tables
Val Hempleman's decompression table helped save many lives by keeping the Royal Navy at the cutting edge in deep diving technology. Hempleman, who was Royal Naval Physiological Laboratory chief from 1968 to 1982 worked 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.
Hempleman revised his tables in 1968. He added a variable rate of tissue tension to ambient pressure. 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 table of decompression
Hempleman published revised diving decompression tables in 1968. These tables allow for a variable ratio of tissue tension to ambient 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.
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 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 modified the decompression tables in 1968 to include a variable proportion of tissue nitrogen tension to ambient. The Navy opposed the changes and refused implementation of the tables. This led Hempleman to change 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 them in 1908, and they continued to use them until the 1950s. The U.S. Navy started using what is now called C and R table in the same decade. This practice became more common in 1980s.