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The value chosen for reserve should be sufficient for the diver to make a safe ascent in sub-optimal conditions. It may require supply of gas to a second diver (buddy breathing) Available gas may be corrected to surface pressure, or specified at a given depth pressure. Available gas at ambient pressure:
The formula simply divides the absolute partial pressure of oxygen which can be tolerated (expressed in atm or bar) by the fraction of oxygen in the breathing gas, to calculate the absolute pressure at which the mix can be breathed. (for example, 50% nitrox can be breathed at twice the pressure of 100% oxygen, so divide by 0.5, etc.).
Ambient pressure is a direct function of the depth. It is atmospheric pressure at the surface, plus hydrostatic pressure, at 1 bar per 10 m depth. [2] Gases quantities will be calculated for bottom gas, bailout gas, decompression gas and travel gas as may be applicable, and each different gas must be carried in one or more dedicated cylinders. [3]
A dive profile is a description of a diver's pressure exposure over time. It may be as simple as just a depth and time pair, as in: "sixty for twenty," (a bottom time of 20 minutes at a depth of 60 feet) or as complex as a second by second graphical representation of depth and time recorded by a personal dive computer. Several common types of ...
In it he derived the relation = (/) ¯ / for the pressure in a gas, composed of particles in motion, with number density /, mass , and mean square speed ¯. He then noted that using the classical laws of Boyle and Charles, one could write m c 2 ¯ / 3 = k T {\displaystyle m{\overline {c^{2}}}/3=kT} with a constant of proportionality k ...
The amount of helium that must be decanted is very simple to calculate: Multiply the desired gas fraction of helium (F He) by the total filling pressure (P tot) to get partial pressure of helium (P He). In the case of the Tx 20/40, in a 230 bar cylinder, this would be 230 bar x 40% = 92 bar (or for a 3,000 psi fill, it would require 3,000 x 40% ...
The shallower depth is called the "maximum operating depth" and is reached when the partial pressure of oxygen in the breathing gas reaches 1.4 bar (140 kPa). The deeper depth, called the "contingency depth", is reached when the partial pressure reaches 1.6 bar (160 kPa). [12]
Equivalent narcotic depth (END) (historically also equivalent nitrogen depth) is used in technical diving as a way of estimating the narcotic effect of a breathing gas mixture, such as nitrox, heliox or trimix. The method is used, for a given breathing gas mix and dive depth, to calculate the equivalent depth which would produce about the same ...