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[1] [2] [12] [13] A maximum oxygen partial pressure of 1.4 bar for the active sectors of the dive, and 1.6 bar for decompression stops is recommended by several recreational and technical diving certification agencies for open circuit, [14] and 1.2 bar or 1.3 bar as maximum for the active sectors of a dive on closed-circuit rebreather ...
The open-circuit saturation curve (also open-circuit characteristic, OCC) of a synchronous generator is a plot of the output open circuit voltage as a function of the excitation current or field. The curve is typically plotted alongside the synchronous impedance curve .
Paschen's law is an equation that gives the breakdown voltage, that is, the voltage necessary to start a discharge or electric arc, between two electrodes in a gas as a function of pressure and gap length. [2] [3] It is named after Friedrich Paschen who discovered it empirically in 1889. [4]
An electronic circuit containing a feedback loop controls the gas-pump current to keep the output of the electrochemical cell constant, so that the pump current directly indicates the oxygen content of the exhaust gas. This sensor eliminates the lean–rich cycling inherent in narrow-band sensors, allowing the control unit to adjust the fuel ...
Open-circuit oxygen apparatus was trialled on the 1922 and 1924 British Everest expeditions; the bottled oxygen taken by the 1921 expedition was not used. The carrying frame for open circuit oxygen designed by George Finch and used in 1922 and 1924 with four cylinders of oxygen weighed 32 lb (14.5 kg).
An open circuit SCBA typically has three main components: a high-pressure gas storage cylinder, (e.g., 2,216 to 5,500 psi (15,280 to 37,920 kPa), about 150 to 374 atmospheres), a pressure regulator, and a respiratory interface, which may be a mouthpiece, half mask or full-face mask, assembled and mounted on a framed carrying harness.
Inspired gas that reaches them is heated to core body temperature and humidified to saturation in the time needed for gas exchange, regardless of the initial temperature and humidity. This heat and humidity are lost to the environment in open circuit breathing systems. When heat loss exceeds heat generation, body temperature will fall. [29]
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.).