Flashcards in Ch. 9 Ventilation Deck (67):
Two main reasons for performing ventilation
Venting for fire
Venting for life
4 problems with thinking ventilation isn't as important because of SCBA's
Ignores victims inside
Assumes FF's mask will always protect
Buildup of heat
Buildings are made tighter (backdraft)
Distinguishing between Vent for Life and Vent for Fire, KEY FACTOR IS:
Timing of ventilation
Life = as soon as possible
Fire = delayed until resources in place to attack
Most important concept when discussing ventilation:
Must be of sufficient volume to WIN!
Break window vs opening
Can stand up, open
Window stuck and not lot of heat/smoke, find another means
Driven back by heat, break WHEN HOSELINE IS CHARGED
Difficulties with double glazed Windows
Can't blow out with hoseline
Inability to clear horizontal sash (more dangerous)
After placement of attack and interior search, this is most crucial: (Chapter 9, Vent)
Outside Vent team
Horizontal vent faster and easier to perform than vertical?
Takes advantage of existing openings
Venting using fog: several factors determine how much air and smoke moved (3)
Velocity = pattern + pressure. 30 degree range of fog
Geometry of opening (6-8 ft back)
Fans not covering opening correctly (exhaust devices - sucking smoke)
Churning - pulls air from outside, to inside and back out - LIMITS EFFICIENCY
2 most common vertical arteries/avenues
2 types of old-style roofs
Standard flat roof: roof joist at roof level, roof boards nailed to joists
Inverted roof: roof boards nailed to framework of 2x4's several feet above main roof joists
Style of roof that has been dominant in the flat roof industry in the last 20 years, at least in the East and Midwest:
Metal deck roof
Dimensions for flat roofs (standard flat roof)
2 x 10's or 3 x 12's beams
16 in apart (carry same load as floors)
Limited to 20 ft span between supports, masonry wall or steel I-beam
Decking is 1 x 6's
Characteristics of older flat roof (old-style)
20-30 years lifespan
3-4 in of tar paper
VERY substantial roof
Relatively safe to work (even over heavy body of fire)
Catastrophic roof failure NOT A CONCERN
Working fire on top floor of any large-area flat-roof requires:
At least 4 members with:
2 power saws, (2) 6 or 8 ft hooks (10 ft for large bldg, cockloft may be 5 ft), halligan, axe, portable radio-preferably officer experienced in ventilation
2 things done immediately upon reaching the roof:
Vent any vertical shafts (bulkhead doors or skylights)
Simultaneously, member can lean over parapet and vent top-floor windows in the fire area with hook or halligan tool clipped to short rope
Simplest, fastest examination hole: 1/4 in. by 10 in.
Size of triangular opening for inspection
8-10 in triangle
First concern after choosing the proper site for venting roof:
Means of escape
Always have 2 ways off the roof
Second concern after choosing proper site for venting roof:
Wind direction-may be first if wind blows smoke/fire and cuts off retreat
When sounding roof, striking with an axe and tool has slight bounce means:
In between joists
Cut close to inside of joists: (2 reasons)
Large an opening as possible
Fewer nails to pull against
Roof hole subdivided into what size:
4 ft x 4 ft max
A spongy feel on an inverted roof means:
Normal for inverted roof
NOT a sign of impending failure
Spacing on uprights - inverted roof
Post 2 ft on center
Rows 4 ft on center
Dangers of rain roof (3)
Delay or prevent ventilation
Insulspan is made of ______ and dimensions are ______.
Styrofoam sandwiched between OSB.
8 ft widths, up to 24 ft lengths
Insulspan difficulties (2)
Styrofoam = highly combustible and toxic smoke/intense flame
As much as 8 1/2 in. thick, circular 4 in. cut, chain saw 9 in. but chain guard doesn't readily allow deep cut
H-typed bldgs or H or E or O shaped
Primary factor in all of these is:
Fairly narrow connecting section called:
Cutting trench ventilation hole; operation not started until:
Main vent hole has been completed
Large dept with 4 or more saws-2 for trench, 2 for main vent hole
Distance trench must be from main vent hole:
Ch. 9 Ventilation
Most likely direction of fire travel is usually downwind side but if little/no wind, __________ may come into play.
Pitch of roof. Travel of fire from low points to high points
2 steps in making roof cut
Choose location for trench
Inspection holes; on FIRE side, 5-6 ft from intended edge of trench
Inspection holes 2 purposes
Fire DIDN'T PASS trench area yet
Indicators of WHEN TO PULL trench
Trench: Hose lines on positioned on roof AND top floor. What size and what intervals/distance?
TOP FLOOR-One 1 3/4 in. per room
ROOF-One for every 15-20 ft trench
Bldg types suited and not suited for trench cuts:
Suited: H-type bldg (O and E as well). Narrow, garden-type apartment complexes
NOT Suited: Supermarkets, Taxpayers, (Better suited multiple large vent holes/hose lines
Greatest danger to firefighters engaged in roof ventilation is:
(Victim almost always someone OTHER THAN saw operator)
Most important act on the roof:
Stop the saw from spinning whenever it is raised from the roof
SAW OPERATORS hold GREATEST RESPONSIBILITY for injury if they fail to stop saw from spinning
Way to stop danger of spinning blade:
Train FFs to never allow spinning blade MORE THAN 6 in. above roof
Hazard to firefighters isn't just from saw but:
Own movement as well
Metal deck roofs are dangerous to operate on over a fire, especially with:
Concentrated load of air conditioners
[Fail with as little as 5 min fire exposure]
Even if you elect to not cut a particular roof:
Someone needs to be sent VERY EARLY at structures LARGER THAN PRIVATE DWELLINGS
Critical items for roof team to report to IC
setbacks or extensions from rear or side not visible from street
Venting using a fog or spray stream is:
One of the EARLIEST AND SIMPLEST means of mechanical ventilation
By far the LEAST DEMANDING in terms of personnel
The danger of fanning into life an otherwise smoldering fire is a problem with __________.
ALL types of mechanical ventilation, since air much larger than natural.
Drawbacks of using a hose stream to vent (3)
Minor fires where water damage is a concern
Poor water supply
_____, ______, ______, and ______ suffer NONE of the drawbacks of the hoseline except forced draft over smoldering embers. (Mechanical vent)
Other portable devices
Special considerations for trench (3)
Must be close enough to fire to limit unnecessary extension but far enough away to complete cut/push ceiling.
Take advantage of bldg contr. and cut at narrowest point.
Estimate likely path and area of greatest value.
Cutting trench (4 steps)
2 parallel cuts about _______ apart
Narrower and fire may jump past it
When dividing up trench...
Cut close to outer walls as possible and the towards center
Divides into 3-4 ft sections
When cutting trench, personnel on fire side must have _____ off the roof, not counting _______.
Jumping the trench
A trench cut is not an _____________ but rather a ____________.
Offensive ventilation hole
Defensive, home-built fire stop
Never ventilate where _______.
You will create an exposure problem
FF's probe roof in front of them with tool. Saw operator should:
Roll saw in front of them and gingerly test each footing before stepping
Another concern for all members, not just roof team, is _______________ an increasingly common situation as crime rate goes up. Consists of _____________.
Steel plating added to roofs for security
4 x 8 sheets of steel, 1/8 to 1/4 in. thick, laid entire surface
If you elect to not cut a particular roof, someone needs to be __________ at structures ____________ to act as ________.
Sent very early to this location
Larger than private dwellings
Eyes and ears of IC
Basic tenet for interior firefighters search for a life hazard is ___________________.
Vent as you move, provided the fire won't be EXTENDED by the venting
*exactly OPPOSITE to make PPV work*
Single vent pipe from pipe chase extends through the roof
To attack fire within building voids, the answer is __________.
All windows and horizontal openings, as well as roof vent
__________ offers firefighters a great opportunity to channel the products of combustion where we want them to go.
Should be a primary tactic at most low-rise, nonfireproof multiple dwellings
Horizontal ventilation for a life hazard must be coupled with _____________. Either ___________ OR _____________.
Immediate rescue effort
Member must enter and remove victim OR
Hoseline must be brought in to protect the victim where he/she is trapped.
Problems with exhaust devices (sucking smoke) (3)
Fans never fit an opening so makeshift method to block off openings around the side (churning)
Debris and other objects drawn against the intake screen
Location of negative pressure fan, hanging in or near doorways
Advantages of Positive vs negative pressure (3)
Don't clutter access routes
Ready ability to remove flammable vapors safely