Scuba & Nitrox Glossary: W

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 — W

Working PPO₂
The oxygen partial-pressure limit selected for the active portion of a dive.
Worst-Case Mix
The mixture assumption producing the most conservative relevant outcome when composition uncertainty is being evaluated; unknown gas should still be analyzed.
Whole-Cylinder Mixing
The time and process required for gases added during blending to become uniform throughout a cylinder.
Warm Fill Reading
Cylinder pressure measured before the cylinder has cooled to ambient temperature.
Water-Vapor Correction
Adjustment considered when humidity affects a gas measurement or calculation.
Working PPO2
The planned oxygen partial pressure for the active portion of a dive.
Worst-Case MOD
A conservative depth limit based on blend tolerance and selected PPO2.
Written Blend Procedure
A documented sequence for safely producing and verifying a gas mixture.

General Scuba Terms — W

Water Column
The vertical body of water between surface and bottom.
Weight Belt
A releasable system used to carry ballast.
Wetsuit
A neoprene exposure suit that traps a thin layer of water and reduces heat loss.
Wing
The inflatable component of a backplate-and-wing buoyancy system.
Working Pressure
The rated service pressure of a cylinder or system.
Wreck Diving
Diving around or inside sunken structures; penetration is an overhead activity requiring specialized training.
Wall Dive
A dive conducted along a steep underwater drop-off.
Vertical Water Column
The body of water extending between surface and bottom.
Wave Period
The time between successive wave crests.
Weight Check
An in-water assessment used to confirm appropriate ballast.
Cylinder Working Pressure
The rated pressure at which a cylinder is intended to be filled and used.