Scuba & Nitrox Glossary: T
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 — T
- Target Mix
- The intended oxygen and, when relevant, helium composition of a gas blend.
- Technical Nitrox
- Nitrox use beyond basic no-decompression recreational applications, requiring additional training.
- Top-Up
- Adding gas to an existing cylinder; the starting composition must be known for accurate blending.
- Trimix
- A breathing-gas mixture containing oxygen, nitrogen, and helium.
- Target FO2
- The intended oxygen fraction for a planned gas blend.
- Top-Off Calculation
- Determining the effect of adding gas to a partially filled cylinder.
- Transfill Hose
- A rated hose used to transfer compressed gas between cylinders.
- Travel Mix
- A breathing gas used to move safely between surface and a deeper operating gas.
- Trimix Analyzer
- An instrument or combination of sensors used to measure oxygen and helium fractions.
General Scuba Terms — T
- Thermocline
- A layer where water temperature changes noticeably.
- Tissue Compartment
- A mathematical model component representing inert-gas uptake and release at a particular rate.
- Turn Pressure
- The cylinder pressure at which a team turns the dive according to the gas plan.
- Task Loading
- The cumulative mental and physical demand placed on a diver.
- Trim
- A diver’s orientation and balance in the water.
- Turbidity
- Cloudiness or suspended material reducing water clarity.
- Tag Line
- A line used to control, guide, or secure equipment or divers.
- Thermocline Boundary
- A layer where water temperature changes rapidly with depth.
- Tide Table
- A prediction of tidal height and timing for a location.
- Tow-Behind Float
- A surface float pulled by a diver to mark position or carry equipment.
- Planned Turn Pressure
- The cylinder pressure at which a team reverses or begins the return phase.