Nitrox workshop dings - Divers Alert Network

Rubicon Foundation Archive (http://rubicon-foundation.org)Gilliam: TDI Nitrox, An Agency perspectiverequire the diver to manually set his mix prior to the dive but some manufacturers have recentlyintroduced computers with integral oxygen analyzers that automatically set the oxygenpercentage. These were aimed at use in rebreathers but clever divers have adapted hardware toallow their use with regular open-circuit scuba gear. Manufacturers have also responded to theway nitrox is being used in the field by expanding the programmable range of their computers.The first nitrox computer produced by Orca Industries in 1992 allowed the use of only 32%nitrox mix. Later, Dive Rite and UWATEC introduced computers with ranges from 21% to 50%.UWATEC's latest offering allows the user to program any oxygen mix from 1% to 100%. Thatreflects the way divers have retreated from the idea that only a couple of mixes would be used.Originally, NOAA published tables for mixes of 32% and 36% since those percentagesmatched up nicely to their scientific dive mission depths. Prior to the introduction of nitroxcomputers that allowed easy use of varied mixes, divers were stuck with those two options.That proved to be over-limiting for several reasons. The 32% mix was widely regarded as theperfect match for sport divers since its 1.6 atm PO2 limit coincided with the 130 foot depth limitfor divers in training. For those wanting to maximize dive profiles at lesser depths, it wasdesirable to use higher oxygen fractions and accept shallower depth limitations. Later, the use ofsemi-closed circuit rebreathers necessitated the use of varying nitrox mixtures based on bothdepth and gas flow through a restricted sonic orifice in the breathing loop. Clearly, one or twonitrox mixes would never satisfy the growing demand to adapt nitrox diving to a nearly infinitelist of applications.The good news is that the industry responded to give divers exactly what they needed: Moreflexibility and choice. Just as early satellite navigation systems (Sat-Nav) provided only latitudeand longitude, global positioning systems (GPS) later incorporated multiple chart way points,automatic computation of all courses and even integration with radar and chart plotters. Nitroxcomputers now provide such a plethora of functions that the user manual can take a long time toread. It's worth taking the time to navigate your way through it. In addition to decompressionfunctions, you can access depth limits based on mix, accumulation of oxygen loading measured aseither central nervous system time allowances or longer term oxygen tolerance units (OTU's). Anamazing series of PC integrated software features let you run pre-dive scenarios and downloadactual dive profiles in real time. You can even set variable oxygen PO 2 limits.Nitrox has clearly found its place in sport diving and continues to gain popularity. Mostliveaboard vessels have embraced nitrox and provide it to guests either at no cost or as a slightadd-on to regular fees. It is in this application that vacationing divers have found its mostworthy use. People dive from liveaboards mostly because they afford maximum diving potentialin great locales. Nitrox and liveaboards go together like wine and cheese. With the right nitroxmix programmed in your computer, it's now possible to literally dive all day (and nightsometimes) without ever incurring a decompression obligation.Dive computers revolutionized how divers conducted themselves in the 1980's. Nitrox in the1990's has forever changed the notion that compressed air was our only choice to breathe. Thecombination of the two technologies has maximized the options for divers worldwide whilemaking dive planning easier, safer and more convenient coupled with another key breakthrough:Affordability.35