Decompression table

Example of a decompression table

A decompression or Austauchtabelle (also abbreviated decorative table called) is used to determine the applicable upon surfacing decompression . The decompression is a function of the maximum diving depth reached, the basic time and possibly present residual saturation with nitrogen in the body tissues , of previous dives calculated (repetitive dives and whose surface breaks) or read. If the decompression stops recommended in the decompression table or other limits are ignored, there is a risk of deathDecompression sickness .

Tables exist for different breathing gas mixtures ( air , Nitrox , Trimix , Heliox etc.) separately for Sea Level (0- 300  m or 0- 700  m ) and mountain dives (about 300 or 700  meters ). Special calculation methods are necessary for saturation dives and gas mixture changes.

history

The first tables and decompression rules were created at the time of the first helmet dives and the first caisson accidents. The medical and physical basics have remained the same since then, only the wealth of experience and knowledge has been greatly expanded. Various decompression models have emerged over time. Based on practical experience with decompression chamber DUTY and various other medical and physical tests and tests for decompression and tissue - saturation - algorithm developed, these mathematical models form the basis of all current decompression tables. In the course of time, the models have been continuously refined, which is why numerous tables, some with different orientations, have been created.

Well-known decompression tables

• US Navy, one of the oldest and most famous tables
• Bühlmann: ZH-L8, ZHL-12, ZH-L16, ZH-L17 etc., from Albert Bühlmann
• Bühlmann cock
• Hahn tables, for example Deco 92 and Deco 2000 from Max Hahn
• COMEX (French diving company), for example CX04
• french Marine, for example MN78, MN90
• Dräger, Haldane (only historical if known)
• NOAA (National Oceanic and Atmospheric Administration, US Department of Commerce)
• Accident prevention regulations BGV C 23 (previously VGB39) (as of 2002)
• RGBM (Reduced Gradient Bubble Model) by Dr. Bruce Wienke, 2002

Form and structure

The deco tables themselves are available in different forms: as pure no-stop tables, as tables for repetitive dives, as card index , print in teaching materials , desktop applications , web forms , mobile apps even as slide rules . Not all tables are primarily intended for the actual dive; some are used solely for dive planning before the dive. The user friendliness and thus the risk of misinterpretation differ depending on the table. While some tables show little more than no-stop dives, others include more demanding decompression dives or multiple repetitive dives (several dives in one day). Decompression tables are used for the medical treatment of decompression chambers and for planning the working hours of overpressure workers in caissons . Today, however, other decompression models are usually used for this purpose than for scuba diving .

Decompressiometer

The decompressiometer is a pneumatic device that was used as a supplement to a table before the advent of dive computers . It is a special form of a depth gauge, consisting of a housing, water pressure membrane, ceramic diffusion membrane and the actual pressure measuring tube and pointer instrument. The pointer instrument is used to physically simulate compression and decompression. The result is displayed on a round scale and indicates the required decompression stages and times.

Dive computer

→ Main article : dive computer

In contrast to tables, today's dive computers are based on saturation simulations, usually with more than one type of tissue. Analogous to the tables, there are dive computers with special modes for special breathing gas mixtures. Repetitive dives, yo-yo dives or the like are also recorded and calculated more precisely. A decompression table always calculates more conservatively than a dive computer, which usually results in more safety reserves.

safety

A problem with all diving tables is that they are based on the assumption of a rectangular profile. The diver must read the necessary decompression stops from the table with the maximum depth and the total bottom time . What may be suitable for professional divers turned out to be a gross oversimplification for recreational divers , who usually begin a slow ascent after reaching maximum depth. The actual saturation is much less with a continuous ascent than with a dive with a rectangular profile. The use of a table is safe in this case, as it specifies extended decompression breaks. However, since the decompression times calculated in this way can be many times the actual required decompression times, diving according to the table is often not practical for recreational divers. The actual decompression obligation can be calculated more precisely and less conservatively with a dive computer.

Rules of thumb

The various rules of thumb are mainly used today to estimate no-stop times and rest times before a flight in an airplane (24-hour rule) or when traveling to higher locations. They only provide vague clues that can be sufficient for the simplest dives. Due to the lack of alternatives, these rules of thumb, which have often been used in the past, cannot offer real security. Therefore, today it is usually recommended to strictly adhere to the instructions of the dive computer. This takes the relevant influences into account in its calculations, even with complicated dive profiles, and gives the diver all the information necessary during and after the dive so that rules of thumb are superfluous.

Web links

• Decor calculator according to the US Navy 93 table Decor calculator according to the US Navy 93 table as an exemplary application and extension of decompression tables.
• Simple decor calculator according to Deco2000 Simple decor calculator according to Deco2000 as an exemplary application and extension of decompression tables.
• A new type of supplemented BGV C 23 table A new type of supplementary BGV C 23 table (previously VGB39) (as of 2002) shows application-relevant formulas and methods. (PDF file; 613 kB)
• Compilation of classic decoration tables

Individual evidence

1. ↑ Diving at higher altitudes - mountain lake diving. (PDF; 788 kB) PADI, accessed June 12, 2019 . 
2. ↑ Jochen van Waasen: DECO92 - 0-700m. Retrieved February 11, 2013 . 
3. ^ Paul Chapman: An explanation of Professor AA Buhlmann's ZH-L16 Algorithm. (PDF) (No longer available online.) Professional Diver Training, December 28, 2018, formerly in the original ; accessed on January 12, 2018 .  ( Page no longer available , search in web archives )  Info: The link was automatically marked as defective. Please check the link according to the instructions and then remove this notice.    
4. ↑ Robert Hefti and Ernie Völlm: Manual saturation - desaturation. (PDF) (No longer available online.) CMAS.CH, 2005, archived from the original on January 12, 2018 ; accessed on January 12, 2018 . Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice.  
5. ^ ^{A b} Thomas Kromp , Hans J. Roggenbach , Peter Bredebusch : Practice of diving : 3rd edition. Delius Klasing Verlag, Bielefeld 2008, ISBN 978-3-7688-1816-2 .
6. ↑ Decompression Meter AKA Bendomatics. The Scuba Museum, Cincinnati Ohio, accessed April 3, 2013 . 
7. ↑ ^{a b} Frank Dolacek: Dive computer for deep diving. Retrieved April 3, 2013 .  
8. ↑ PADI : Open Water Diver Manual - with computer, Chapter 5, No. 70204G, 2014

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !