CSE (Firescaping) Flashcards
3 Elements of Fire
Fuel, Heat and Oxygen
3 that explain how fire spreads
Conduction, Convenction and Radiation
Fire hazard area is defined by what
Proximity to Wildlands
Weather
Terrain
Vegetation
Emergency Access
History
Wildlands Definition
Any large plot of land that is not maintained and where the vegetation can naturally grow and reproduce.
Grasslands, weedy hills, chaparral , floodplains, mixed evergreen and conifer forests, even alpine and marshy environments
What is the most dominant factor determining whether a wildland will erupt in flames?
Weather
What is a “Red Flag Day”?
Red flag day means fire weather. It is distinguished by low humidity, hot temperatures, and moderate -high winds.
Feohn Winds Definition
Rapid rise in temperature and a big drop in humidity. Often they are fast, gusty and erratic.
Also called Chinook, devil, diablo, katabolic winds, or pressure differentials.
What is the “Lee Effect”?
The lee effect is produced when a strong wind runs into a mountain and drops its moisture as it is pushed upslope, eventually becoming compressed at the peak and running down the leeside of the mountain, becoming drier and faster as it travels.
Katabolic Winds
Those that rush down a slope pushed by nothing more than gravity, gaining speed and losing moisture as they drop. Sundowners are often katabolic and occur when heat generated breezes have been shoved up a mountain all day, only to die down a sunset and descend
Pressure Differentials
When a high-pressure weather system sits over the Great Basin and a low-pressure system sits off the coast, the high-pressure flows to the low and winds heat up, dry and strengthen as they are shoved up and over the mountains and through the valleys and passes
Dry ground cover no higher than 2’ tall will produce 9-foot flames in 5mph winds. How tall will the flames be at 20mph?
19 feet
What three types of terrain are most fire prone?
Slopes, in canyons and valleys and on ridgetops
What % slope doubles length of flame?
10%
If a fire on flat ground has 6 foot flames, how long will the flames be on a 20% slope?
24 feet
What is the Venturi effect?
is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe. Like putting your thumb over the end of a hose to make it spray more forcefully
What are the three measures of evaluating vegetation for fire danger?
Ignitability, Sustainability and Combustibility
What is ignitability in terms of vegetation?
Ignitability is determined by measuring the time it takes a plant to burst into flames when exposed to grass or forest fire temperatures (roughly between 650-1100 degrees farinheight)
What is sustainability in terms of vegetation in a fire?
Sustainability is defined by the amount of time a plant or landscape can sustain a fire. Sustainability is determined by the amount of dry fuel.
What is combustibility in terms of vegetation in a fire?
Defined by the amount of heat a plant or landscape produces when inflamed. Amount and density of the dry fuels determines the combustibility of a plant or landscape.
What are some requirements of the federal government with regard to structures in fire hazard areas?
-Roof must be Class A (the most fire resistant)
-A noncombustible sheet must sit between the roof tiles and the plywood
-Air vents are screened with 1/8” mesh that is both noncombustible and corrosion resistant. Agencies in extra-high fire risk areas may require 1/16” screen.
-Siding and the undersides of eaves and soffits must be constructed of no less than ignition-resistant material. Noncombustible is always preferred.
-Exterior windows must be glazed and double-paned
-doors and openings must be constructed of ignition-resistant materials.
-Chimney outlets must have a screen
-Portions of a structure that overhang a slope must be skirted to grade with no less than ignition-resistant materials.
What are some requirements of the federal government with regard to Defensible Space in fire hazard areas?
-A firebreak must be maintained at least 30 or 50 feet around a structure or property line, whichever is closer
-Landscape features, such as decks and shade structures, must be constructed from ignition resistant materials. Noncombustible building materials, such as metal and stone, may be required in extra-high fire hazard areas.
-Trees next to a structure must be kept clear of deadwood
-Wild vegetation must be mowed to 18 inches.
Zone 1: The Garden Zone/Defensible Space
30’ from all sides of house or structure. Must withstand heat between 900-1,300F.
Plants should wilt and sizzle, not ignite. Maint is most expensive and intensive here.
Zone 2: The Greenbelt/Fuel Break
31-70’ from a protected structure. Add 10’ for every 10% increase in slope. Should stop a ground fire. Select low growing, hearty and water thrifty plants which are the most fire resistant.
Zone 3: The Transition Zone
Starting at 71’ (farther on slopes) extends to 120’ (on flat ground). Acts as buffer between domestic and natural. Controlling weeds, managing stormwater, reducing erosion and improving biological diversity are important. Keep trees and large shrubs isolated by two times their mature height. Mow wild grasses to 6”.
Zone 4: The Native or Natural Zone/ Open Space
Manage existing fuels, usually by these three methods: Mechanical Removal, Grazing and Prescribed Burns
