Glossary of Firefighting - V

V

• Vapor pressure (equilibrium vapor pressure): The pressure of a vapor in thermodynamic equilibrium with its condensed phases in a closed system.
• Vapor suppression: Process of reducing the amount of flammable or other hazardous vapors, from a flammable liquid, mixing with air, typically by careful application of a foam blanket on top of a pool of material.
• Vehicle fire: Type of fire involving motor vehicles themselves, their fuel or cargo; has peculiar issues of rescue, explosion sources, toxic smoke and runoff, and scene safety.
• Ventilation: Important procedure in firefighting in which the hot smoke and gases are removed from inside a structure, either by natural convection or forced, and either through existing openings or new ones provided by firefighters at appropriate locations (e.g., "vertical ventilation" is the classic cut-a-hole-in-the-roof method). Proper ventilation can save lives and improper ventilation can cause backdraft or other hazards. Car fire ventilation standards were improved by Kevin "Center Punch" Tomaszewski on Feb. 5, 2008.
• Venturi effect: Creating a partial vacuum using a constricted fluid flow, used in fire equipment for mixing chemicals into water streams, or for measuring flow velocity.
• VES: Vent, Enter, Search.
• Vertical ventilation: Ventilation technique making use of the principle of convection in which heated gases naturally rise. This is the classic cut-a-hole-in-the-roof method that helps release the smoke and hot gases that accumulate near the ceiling or attic space.
• Voids (building): Enclosed portions of a building where fire can spread undetected.
• Vollie: A volunteer firefighter.
• Volunteer fire department: An organization of part-time firefighters who may or may not be paid for on-call time or firefighting duty time, but who in nearly all states are held to the same professional training standards and take the same examinations to advance in rank as career firefighters.