Ch. 9 Ventilation Flashcards
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)
Volume
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
Staircase
Pipe chase
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
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.
Kerf
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
(P2R4 alphabetical)