Ch. 14 Mission of Exposure Flashcards
Exposure protection involves the _______ part of the extinguishment process - ________ the fire.
First.
Confining.
___________ is to prevent the spread of and ____________ in the assigned area.
Mission of exposure.
Extinguish any fire.
Heat transferred from one molecule to another as molecules come in direct contact with each other
Conduction
______________: Flame of burning object comes in contact with another object - most significant in _______ fires.
Direct flame impingement:
-Incipient
Transfer of heat in the form of electromagnetic waves that travel in straight lines from the source of the fire.
Radiation
Moves through a circulating medium
Convection
This method is responsible for most of the fire spread inside a structure
Convection
Two types of exposure
Interior and exterior
Two basic forms of interior exposure
Horizontal and vertical
This form of interior exposure is cause mostly by radiation and direct flame impingement
Horizontal interior exposures
room to room
This interior exposure caused by convection currents
Vertical interior exposures
floor to floor
Items of value outside the structure or area of origin that could be threatened by fire.
Are normally, but not exclusively, other structures.
Exterior exposures
Plants and shrubs.
Toys.
Bikes.
Fencing.
Questionable exposures
Extinguishment process has three components
Confine (nozzle in between).
Control (cooling gases).
Extinguish (overhaul).
Need for protecting exposures depends on (3)
Number of BTUs being produced.
Ignition TEMPERATURE of exposed material.
DISTANCE the material is from the heat source.
Interior exposures are mostly affected by _______ heat, although ______ heat will ignite materials in an area more horizontal.
This indicates interior exposure fire tend to spread _______ rather than ________.
Convected
Radiant
Upward.
Horizontally.
To protect horizontal interior exposures, locate the seat of the fire and ________________.
Place a hose stream between the fire and its expected avenue of spread
close the door to involved room. Most home doors rated for 20 min
To protect vertical interior exposures, locate the source of heat and _________________________.
Stop or check the spread of heat by convection currents.
- straight stream off ceiling.
- MANDATORY to get above fire as soon as knocked down.
Two big errors with crews assigned to exposure
First, directing stream predominantly onto original fire, neglecting exposure.
Second, MOST COMMON error is not starting with large enough line. Line LARGER than 1 3/4 in.
2 1/2 in. should be FIRST line pulled
Exposure line may have to be moved back so that an effective stream can cool the _____ in the same manner as the exterior side walls
Roof
No doubt what INTERIOR exposures deserve your attention first, ______ currents will demand that you check extensions to the ______ exposures first.
Convection.
Upper.
Exterior exposure factors (5)
Availability of add'l companies. Wind direction. Wind speed. Proximity of exposed buildings. Life safety
Exterior exposure factors.
Probably as big of an influence as any:
Wind (direction).
- directs course of INTERIOR fire spread*
- choose exposure on LEE side*
Exterior exposure factors.
Direct correlation between this and effect on exposures:
Wind SPEED.
More force, more spread
