Glossary of SCUBA Diving - G

G

gas blending

Mixing breathing gases for diving, filling diving cylinders with gas mixes such as nitrox or trimix.

gas embolism

Blockage of blood vessel by a bubble of gas.

gaseous impurities

Contaminants in the compressed breathing air or gas mixture which are in gaseous form. Compare with particulate and condensate impurities.

gas fraction

The fraction by molecular count, volume or pressure (they all come to the same thing) of a specific gas in a mixture of gases.

gas panel

Further information: Surface supplied diving#Gas panel

The control equipment for providing breathing gas to surface supplied divers via umbilicals. Primary and reserve gas is supplied to the panel through shutoff valves from a low pressure compressor or high pressure storage cylinders.

gauge pressure

Gauge pressure is zero-referenced against ambient air pressure, so it is equal to absolute pressure minus atmospheric pressure

gauge snubber

A needle valve or small bore orifice between the pressure supply and the gauge which damps pressure fluctuations.

glowstick

A single-use, translucent plastic tube containing isolated substances that, when combined, make light through chemiluminescence

Goodman handle

A handle used to carry the primary dive light head comprising a rigid slot through which the fingers and palm of the hand are extended, so that the light rests on the back of the hand, facing the direction of the extended fingers.

GPS

A satellite navigation system that provides location and time information in all weather, anywhere on or near the Earth, where there is an unobstructed line of sight to four or more GPS satellites

gradient factor

Further information: Decompression (diving)#Gradient factors

A way of modifying the M-value to a more conservative value for use in a decompression algorithm.