Add to Wishlist. This is a highly useful tool as it will allow divers to monitor their oxygen exposure levels when diving on enriched air or technical gases as well as calcluating the equivalent air depth for dive planning. However, the smart and safe diver always has a backup plan, just in case. This is the Metric version of the table which is printed on a plastic dive slate making it highly durable and waterproof.
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To determine an EAD with these tables, simply look across the top row to find the nitrox mix based upon the fraction of oxygen, expressed as a percentage , then proceed down that column under the mix to find the actual or next greater depth appearing in bold type, in that column , and finally read across that row to the far left to identify the equivalent air depth. Using the EAD with Air Dive Tables In nitrox dive planning, the EAD information once determined is simply applied to a standard set of air dive tables; the tables plot the dose of nitrogen experienced by the diver, based upon depth and time.
In practice, a diver certainly may use any air dive tables with which he is comfortable. The TDI version of the US Navy dive tables again are used here for demonstration, with the same tables depicting both Metric and Imperial values depicted below. When using nitrox, the no-decompression limit is calculated as usual on the air dive tables, simply with the EAD used in place of the actual depth.
The ending pressure group, for any dive, is also calculated in the usual manner, again with the EAD used in place of the actual depth. Surface interval credit is calculated in the normal fashion after all, regardless of the mix that a diver may use at depth, he will still be breathing air back on the surface during the surface interval. Example: Surfacing in pressure group G, followed by a two hour surface interval, the diver will then be in pressure group D.
In planning for a repetitive dive, the diver may use the same or a different nitrox mix; in either case, the EAD is again used to determine the residual nitrogen time. The residual nitrogen time is then added to the actual time at the EAD, to determine the ending pressure group. For more information please contact TDI; Tel:
The equivalent air depth EAD is a way of approximating the decompression requirements of breathing gas mixtures that contain nitrogen and oxygen in different proportions to those in air, known as nitrox. The equivalent air depth, for a given nitrox mix and depth, is the depth of a dive when breathing air that would have the same partial pressure of nitrogen. So at 27 metres on this mix, the diver would calculate their decompression requirements as if on air at 20 metres. So at 90 feet on this mix, the diver would calculate their decompression requirements as if on air at 67 feet. In practice, it is much more convenient to work with the equivalent columns of seawater depth, because the depth can be read off directly from the depth gauge or dive computer.
Equivalent air depth
You should seek qualified instruction before diving or using nitrox. Unlike climbing, the diver can run into the limits of human physiology quite easily. There are three constraints that are relevant to the discussion:. Narcosis: Both nitrogen and oxygen can have narcotic effects at pressure. People report euphoria, cognitive impairment, sleepiness, hallucinations, terror, etc. Hence, recreational diving is not generally done below feet. This hypothesis is consistent with the fact that more nonpolar gases seem to be more narcotic.
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