|Powered Artificial Gill|
|Powered Artificial Gill|
Artificial Gills were designed to extract oxygen from water and are complex devices, which allow a virtually unlimited amount of time underwater. Some models have CO2 absorbent chemicals to eliminate bubbles for covert dives.
An air tank included in the mechanism carries a charge of nitrogen or helium, which is mixed with extracted oxygen. Exhaled carbon dioxide is eliminated, with the helium or nitrogen being recirculated. A pulse sensor in the mask adjusts oxygen extraction to match the exertion of the user.
To make sure the gill provides enough oxygen even if the wearer is not moving, additional water must be forced over the gas exchanger. The basic version of the gill uses the wearer's muscle power to pump the water and operate the gas exchange. But in addition to swimming this can be tiring, restricting the gill's use to a few hours. The enhanced version includes a battery pack usable for up to 12 hours. The battery drives water over the gill and run the gas exchange.
The artificial gill functions only in thin, standard, and dense atmospheres. Since the gill also extracts other dissolved gases from the water, it may be dangerous to use the gill on worlds with tainted atmospheres.
A variant of the artificial gill, the Powered Gill is similar in function but quite different in actual design. Using a power pack to provide the high levels of energy required, the powered gill converts water to hydrogen and oxygen; it expels the hydrogen and combining the oxygen with a carried nitrogen supply. The powered gill has all of the same basic limitations as the artificial gill, but it is lighter. Power supply is good for 36 hours of use between recharges. Bubbles (from hydrogen, broken down by the unit) cannot be masked.
The two chief dangers involved in using the artificial gill are anoxia and hypoxia.
Anoxia occurs in some layers of water where oxygen content is too low to allow extraction. This is normally a rare occurrence but should be watched for. Victims of anoxia must be given air within five minutes, or they will probably die.
Hypoxia occurs when a fault in the mechanism delivers an insufficient volume of the mixed gas (nitrogen or helium) to the diver. Shots of pure oxygen have an intoxicating effect and should be treated much like nitrogen narcosis. Hypoxia is based on the reliability of the gill.
At TL–13, a miniaturized refinement of the standard powered gill employs the same principles but is much smaller. It consists of a lightweight, mouthpiece-type breathing device with a small battery and a container of pressurized nitrogen attached to the unit. The unit will not accept helium, and thus it is limited by the threat of nitrogen narcosis to pressures of 3 atmospheres or less. Total operating time is no more than 1 hour.