Scuba & Nitrox Glossary: L
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 — L
- Label Verification
- Checking that cylinder markings, measured gas, maximum operating depth, and planned use agree.
- Linearity Check
- Testing an analyzer at more than one known oxygen level to confirm reliable response across its range.
- Low-Oxygen Alarm
- A rebreather or monitoring warning that oxygen partial pressure has fallen below a configured threshold.
- Lean Nitrox
- An enriched-air mix with a relatively modest oxygen percentage.
- Live Mix Reading
- A real-time analyzer measurement during gas production or transfer.
- Loop FO2
- The fraction of oxygen present in a rebreather breathing loop.
- Loop Volume
- The quantity of gas circulating through a rebreather loop.
- Low-Flow Sampling
- Presenting gas slowly and consistently to an oxygen sensor for analysis.
General Scuba Terms — L
- Lift Bag
- An inflatable bag used to raise or support an object; it requires specific training and careful buoyancy management.
- Liveaboard
- A vessel providing accommodations and multiple days of diving.
- Logbook
- A paper or electronic record of dives.
- Low-Pressure Hose
- A hose carrying intermediate-pressure gas from a regulator first stage.
- Low-on-Gas
- A condition in which remaining gas has reached a predetermined reserve or turn pressure.
- Ladder Exit
- Leaving the water by a vessel or shore ladder using a controlled procedure.
- Lateral Current
- Water movement across rather than along a planned route.
- Lead Diver
- The team member assigned to navigation or primary route leadership.
- Light Signal
- Communication made with a dive light, especially in darkness or overhead environments.
- Line Trap
- A passage configuration that can prevent a guideline from following the safest route.