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The usual meaning of diving helmet is a piece of diving equipment that encases the user's head and delivers breathing gas to the diver, but the term "diving helmet", or "cave diving helmet" may also refer to a safety helmet like a climbing helmet or caving helmet that covers the top and back of the head, but is not sealed. These may be worn ...
Shallow diving is an extreme sport, whereby enthusiasts attempt to dive from the greatest height into the shallowest depth of water, without sustaining injury. It is typically associated with traveling circuses along with the strongman , performing animals , clowns and other such attractions.
Standard diving dress, also known as hard-hat or copper hat equipment, deep sea diving suit or heavy gear, is a type of diving suit that was formerly used for all relatively deep underwater work that required more than breath-hold duration, which included marine salvage, civil engineering, pearl shell diving and other commercial diving work, and similar naval diving applications.
Free-flow diving helmets avoid the dead space problem by supplying far more air than the diver can use, and eliminating the oro-nasal compartment. This makes the whole interior of the helmet effectively fresh air, as it is adequately flushed during and after each exhalation at the cost of significantly higher gas usage in open circuit systems.
Lightweight demand helmets are rigid structures which fully enclose the head of the diver and supply breathing gas "on demand". The flow of gas from the supply line is activated by inhalation reducing the pressure in the helmet to slightly below ambient, and a diaphragm in the demand valve senses this pressure difference and moves a lever to open the valve to allow breathing gas to flow into ...
The MOD is significant when planning dives using gases such as heliox, nitrox and trimix because the proportion of oxygen in the mix determines a maximum depth for breathing that gas at an acceptable risk. There is a risk of acute oxygen toxicity if the MOD is exceeded. [1] The tables below show MODs for a selection of oxygen mixes.
MOD for a closed circuit mixed gas rebreather is usually based on the MOD of the diluent, as that is the leanest mix that can be guaranteed. After a diluent flush the gas must be breathable, and this limits MOD, but it is possible to use more than one option for diluent, and switch the gas to a hypoxic mix for the deeper sector of a dive, and a ...
Underwater diving is practiced as part of an occupation, or for recreation, where the practitioner submerges below the surface of the water or other liquid for a period which may range between seconds to the order of a day at a time, either exposed to the ambient pressure or isolated by a pressure resistant suit, to interact with the underwater ...