12 Horizontal Ventilation Flashcards
Advantage of electric fans over gas powered fans
Electric is quieter and don’t produce exhaust, preferred over gas, though gas powered may move more air
Disadvantage of hydraulic blower fan
Can add water damage if they leak
Flexible ducting for vent fans can be used in what type of fans
Both negative and positive pressure fans.
Two types of ducting
Flexible translucent plastic up to 24” in diameter kept open by pressure pushing through it
Treated fabric over metal coil kept open by metal coil
Electric blowed can be placed inside the building to expel smoke out through ducts. If electric is not available, a gas blower should be positioned
Outside the building with ductwork going into the building, blow fresh air through duct into the compartment, forcing out the smoke with positive pressure
Vent blower ducts are used in what situations.
After the fire is controlled, moving smoke out that is cold, move smoke out of a compartment without pushing it through the rest of the space, contaminating clean spaces.
Vent ductwork can be used to remove smoke from confined spaces like attics, and basements, it can also provide fresh air for
Crews working long term in confined spaces, vaults, sewers, silos.
When ejecting smoke what needs to replace the smoke removed
Fresh air needs to replace smoke removed in order for it to work.
When working or venting below grade, what should be monitored
Air quality for possible heavier than air gasses.
Fixed window
Doesn’t open, sometimes flanked or paired with double hung or casement windows
Single and double hung windows
Single hung windows only have one moveable section
Double hung, both sections or halves are moveable.
Only half the window space is available for ventilation in both
Casement window
Outward swinging hinged sashes opened by hand crank. Double casement windows are side by side, separated by a mullion.
Mullion
A vertical division between multiple windows or a double door opening.
Horizontal sliding windows
Two or more horizontal sashes, one is fixed,sash can be slid sideways or removed from inside.
Awning windows
One or more top hinged, outward swinging sashes.
Jalouise windows
Narrow horizontal panes of glass in pivoting bracket at end. Oliver like windows. Difficult to open from outside without breaking.
Projected windows.
Aka factory windows. May be top or bottom hinged, outward swinging. Like windows at Kristina’s school
Hopper windows.
Bottom hinged inward swinging sashes
Energy efficient windows
Double or triple glazed. Space between lanes are filled with inert gas.
Energy efficient windows are commonly referred to as
Thermal windows
Thermal or energy efficient windows hold more heat and break later than conventional, causing what during a fire
Longer time to self vent, promote spread and intensity of fire, longer time for passerby to notice
When horizontal vent is needed, windows that resist opening from the outside usually can and should be
Broken out.
For venting Lexan type windows that resist breaking, the fastest way is
To remove the entire frame and window, by cutting out if needed, than breaking.
Doors can make horizontal ventilation very effective because
Their opening is larger than windows.
Doors that need to be opened for vent should be blocked open instead of removed because
Blocking allows the door to be closed later if the vent profile needs to be changed.
Mot common type of exterior doors used for tactical venting
Swinging doors
Sliding doors
Overhead doors
Roll up doors
Two types of sliding doors
Exterior sliding doors, interior sliding fire doors.
Before fire doors are reopened, firefighters must make sure of what
That there is no longer any danger of fire spread through the door.
Interior sliding fire doors should be blocked open because
If they activate during operations, they can trap firefighters or kink hose lines
Telescoping doors have two skins separated by air space at least how wide
2”, gradually getting larger as you move up so there is more space for the lower door components to nest inside, can be more than 13 inches at top
Target hazard
Facility where there is a great potential likelihood of life or property loss in the event of an attack or disaster or fire
Stem wall
Wall between foundation footing and first floor.
In the case of fire walls, ventilation might need to be performed on what side
Both sides of the fire wall
Generally firewalls should not be breached for ventilation because
It can feed fire and spread fire to protected parts of the building.
Masonry and concrete walls can be what range in thickness
8-12” or more
Exterior insulating finishing systems EIFS, can be as thick as
One foot
EIFS can be detected by
The hollow sound made when tapped by a tool
Wall ties
Thin corrugated pieces of metal that attach exterior masonry veneer
Horizontal ventilation is usually done by opening a window near the seat of the fire and using what as an inlet opening for air
The entry point or door
Important factors to be considered in a plan for horizontal vent
Location of fire
Wind direction and speed
Location of vent openings
Exit opening is usually made where
As close to the fire as possible and on opposite side of from where fire attack is made
It may be possible to combat windward side pressurization from wind to the fire by
Using ppv on the leeward side
The most often used horizontal ventilation
Natural
Interior doors may by systematically opened and closed one at a time to achieve
Controlled ventilation of different compartments
Screens curtains or blinds should be removed from windows when venting because
They may hinder airflow.
Compared to inlet openings, how large should exit openings be
Exit openings should be about twice as large as inlets
If a fire is on the leeward side, what windows must be opened first
The tops of the leeward windows to let smoke out first, then windward side to facilitate the movement.
Smoke ejectors were designed for
Drawing out heat and smoke and to withstand the temperature and contamination, except flames can damage it
Unless smoke ejectors are equipped with intrinsically safe motors, they should be used after the fire is out because
They might ignite fire gasses
What side of the building are smoke ejectors usually set up
Leeward side.
Churning, or recirculating of fire gasses around a smoke ejector, can be prevented by
Hanging a salvage cover around the fan and open space of the opening.
How far back are ppv blowers typically set up
6 feet back from opening so it can cover the entire opening
How many blowers are usually sufficient for pressurizing a building
One
For larger structures how many ppv should be used if needed
Two in tandem, (one behind the other)
Compared to mechanical smoke ejectors, fog streams can move how much more smoke volume
2-4 times more depending on type, gpm and position of streams
For hydraulically venting a fog stream should be placed how
With a 60* pattern covering 85-90% of the opening. Appx 2’ away from window.
A spray pattern for a fog nozzle hydraulically venting should not exceed 60* because
It looses efficiency the wider it gets.
Disadvantages to hydraulically venting
Increased water damage
Drain on water supply
Icy conditions inside and out when cold
Nozzle operator remains in hostile environment
May have to be interrupted if Scba goes empty
For horizontal venting to be effective, a proper balance between volume of air introduced and what must be maintained
Balance between volume introduced and size of exit openings
Contents of building can be improperly positioned or stacked in hallways and near openings, causing what
Disturbance of ventilation
If the fire is on the windward side, ppv doesn’t counteract the wind because wind velocity is too high, and vertical venting is impractical. Ventilation should
Be delayed until the fire is under control, ff must be alert for sudden fire behavior changes however.
Horizontally venting fire can spread into an attic through
Eave vents
