Lesson 7


1. The air that we breathe is composed of a mixture of gases, for simplicity let’s say that is made up mainly of________________________
2. At a depth of 15 metres, the pressure inside the lungs will be the equivalent of the ambient pressure:
3. Nitrogen narcosis effects different divers differently depending on the ___________________
4. If you ascend too quickly the nitrogen is cannot be released quickly enough thus contributing to the formation of bubbles in the divers __________
5. First aid for Decompression Sickness: the application of pure oxygen guarantees greater oxygenation of __________ and helps to lessen the risk of damage
6. The rules for the prevention of decompression sickness can be divided as follows:
7. During this course all dives will be performed within the limits of non-decompression
8. On dive tables the time and depth of the dive are correlated.
9. When you plan a dive the first thing is to establish the maximum depth to be reached, for examples 13 metres, naturally considering 15 metres on the tables following down the column the limit of permanence at this depth is shown at 100 minutes. Planning to dive for 35 minutes, 30 minutes must be calculated. At this point on the right the corresponding dive letter group, in this case F is found.
10. Now, wanting to plan a second dive, after a break on the surface of 3 hours and 29 minutes, moving to the right to find the box corresponding to this time, we find the interval from 2 hours 29 minutes to 3 hours 57 minutes. Below the new dive letter group is indicated: in this case C.
11. The change of dive letter group shows that the tissues have got rid of a part of the nitrogen during the interval on the surface. Now wanting to plan a second dive where the maximum depth must never exceed the previous one, in this case 14 metres for 25 minutes, the first thing is to find the minutes which penalise the dive and add them to the real dive time. To do this one follows down under letter C to the point corresponding to the maximum depth programmed, always calculating the higher figure. This cross check between letter C and the depth of 15 metres gives 21 minutes. This means that a dive of 25 minutes must be calculated at a total time of 46 minutes.
12. A personal dive computer can calculate the exact saturation state of our tissue

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