Glossary of SCUBA Diving - V

V

Valsalva maneuver

Technique for equalising the middle ear by moderately forceful attempted exhalation against a closed mouth and blocked nose

vasoconstriction

The narrowing of blood vessels resulting from contraction of the muscular wall of the vessels, particularly the large arteries and small arterioles.

vasodilation

The widening of blood vessels resulting from relaxation of smooth muscle cells within the vessel walls, particularly in the large veins, large arteries, and smaller arterioles.

vertigo

A type of dizziness, where there is a feeling of motion when one is stationary.

viewport

1. Glass or plastic window on a diving helmet or full face mask.

2. Window on a hyperbaric chamber.

visual inspection

Internal and external inspection of a pressure vessel as part of revalidation procedure

Visual Plus

Eddy current test (q.v.) of parallel neck threads of aluminium cylinders