A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Wall-indicator valve
Type of control valve for sprinkler systems which is mounted to an outside wall and indicates open" or "shut" in an indicator window on the valve body.

Watch out situations
A list of 18 situations for firefighters to be aware of, which signal potential hazards on the fire line.

Water curtain nozzle
A nozzle designed to throw a fan of water droplets to form a curtain" in an attempt to reduce radiated heat from igniting a nearby exposure.

Water drop
A forest fire fighting technique when an aircraft drops a supply of water onto an exposed fire from above.

Water flow alarm
An audible alarm indicating that one or more sprinkler heads have been activated.

Water hammer
Large, damaging shock wave in a water supply system caused by shutting a valve quickly, or by permitting a vehicle to drive across an unprotected fire hose.

Water mist fire suppression
A sprinkler-like system that uses a very fine mist featuring much lower water flow than conventional sprinklers to suppress, rather than extinguish, a fire[1].

Water tender
Any ground vehicle capable of transporting specified quantities of water.

Water thief (valve)
Type of gated wye having one or more outlets smaller than the largest outlet.

Wedges
Wooden blocks for temporary shut-off of activated sprinkler heads or holding doors open during firefighting or rescue operations.

Wet line
Temporary control line using water or other fire retardant liquid to prevent a low-intensity fire from spreading in surface fuels.

Wet pipe sprinkler system
Sprinkler system containing pressurized water rather than air, such that water will flow immediately upon release of a heat-sensitive head.

Wet water
Water into which a surface tension reducing agent has been introduced. The resultant mixture, with its reduced surface tension, is more able to penetrate burning product more deeply and extinguish deep seated fire.

Wildfire
A fire occurring on wildland that is not meeting management objectives and thus requires a suppression response.

Wildfire or Wildland fire
Fire in forests, grasslands, prairies, or other natural areas, not involving structure fires (although wildland fires may threaten structures or vice versa - see interface zone.) For a complete list of terms used in wildland fire, see Glossary of wildland fire terms.

Wildland
An area in which development is essentially nonexistent, except for roads, railroads, power lines, and similar transportation facilities. Structures, if any, are widely scattered.

Windfall
Tree knocked over or broken off by wind, increases fuel loading and hampers building fireline. Also sometimes called blowdown.

Working fire
A fire that is in the process of being suppressed; often a cue for dispatch of additional resources.

Wye
Device used to split a larger supply line hose into smaller attack line hoses. A gated wye contains valves so that certain lines can be turned on and off.

Wye
Hose coupling for splitting one line into two or more outlets, often a larger line split into two smaller ones; often a gated wye having separate valves for each outlet. Not to be confused with Siamese, which is used to bring two smaller lines together into one.