Scuba & Nitrox Glossary: G
Nitrox and breathing-gas terminology is prioritized first. General scuba terms follow below. Definitions are educational summaries and do not replace formal training, manufacturer instructions, or an operational dive plan.
Nitrox & Gas Terms — G
- Gas Analysis
- Measurement of oxygen, helium, or other components in a breathing-gas mixture.
- Gas Blender
- A person trained and authorized to prepare breathing-gas mixtures.
- Gas Compatibility
- Suitability of equipment and materials for exposure to a particular gas and oxygen concentration.
- Gas Density
- Mass of gas per unit volume; density increases with pressure and affects breathing work.
- Gas Switch
- Changing from one breathing gas to another according to a verified plan and procedure.
- Gas Bank Equalization
- Balancing pressures among storage cylinders or fill banks.
- Breathing-Gas Compatibility
- Suitability of a mixture for its cylinder, valve, regulator, and planned depth.
- Gas Density Limit
- A planning limit intended to manage work of breathing at depth.
- Gas Identification Tape
- Color-coded or printed tape used as supplemental cylinder identification.
- Gas Switch Confirmation
- Team verification of cylinder, label, regulator, and depth before breathing a new gas.
General Scuba Terms — G
- Gas Management
- Planning and monitoring breathing-gas supply, consumption, reserves, and contingencies.
- Gas Sharing
- Providing breathing gas to another diver.
- Gauge Pressure
- Pressure measured relative to surrounding atmospheric pressure.
- Giant Stride
- A common entry technique from a stable platform or boat.
- Guideline
- A continuous line used for navigation in overhead or limited-visibility environments.
- Giant-Stride Entry
- A common entry performed by stepping outward from a stable platform.
- Gradient
- The difference in pressure or concentration that drives gas movement.
- Granny Line
- A surface line running from a boat toward its descent line for diver assistance.
- Green Water
- Water colored by plankton or suspended material, often with reduced visibility.
- Ground Swell
- Long-period wave motion that can affect divers near the bottom.