Book 29 Ventilation Techniques Flashcards
Book 29 Ventilation Techniques -
Ventilation is the “_____” removal of heat, smoke, and fire gases from a structure, and replacing it with cooler, clean, fresh air. Ventilation does NOT put out fires. However, effective ventilation DRAMATICALLY assists in the attack, control, and extinguishment of a structure fire.
“systematic”
Book 29 Ventilation Techniques -
Effective ventilation will accomplish four main objectives.
- Save lives.
- Assist in firefighter access.
- Control the horizontal spread of fire.
- Reduce the possibility of flashover and backdraft.
Book 29 Ventilation Techniques -
Flashover is a condition where all of the contents of a room are heated to their ignition temperature. Once their ignition temperature is reached, the entire room will quickly be involved in flames. Each year in the United States, there is an average of __ deaths to firefighters in the fire service. On an average, __ of those deaths are due to flashover, and the number is slowly rising each year. Proper ventilation helps eliminate this condition because the heat is removed from the structure before the contents reach their ignition temperatures.
100 deaths to firefighters in the fire service. On an average, 85 of those deaths are due to flashover,
Book 29 Ventilation Techniques -
In order to properly and safely open a roof, you must have a good working knowledge of _____. The key to safe and effective roof ventilation is the knowledge of rafter type and rafter direction.
building construction
Book 29 Ventilation Techniques -
There are basically only TWO (2) types of ventilation holes:
Heat Hole (Offensive) Strip Ventilation (Defensive).
Book 29 Ventilation Techniques -
When exposed to fire, roofs built with lightweight truss construction will fail at a very fast rate, resulting in a significantly reduced time for the roof team to operate. When operating on a lightweight truss roof (or suspected lightweight truss), the ventilation team shall never conduct ventilation operations directly over the fire. Members should employ the practice of “trading space for time” so that they may complete their roof-cutting operation prior to the fire impinging on a given ventilation hole. Rafter direction is important to know because we usually cut 1” x 4” and 1” x 6” sheathing parallel to rafters. On roofs sheathed with plywood, the “Head Cut” is made perpendicular to rafters. You need to know rafter direction in order to accomplish any Heat Hole or Strip Ventilation Hole.
Reference
Book 29 Ventilation Techniques -DIAPHRAGM NAILING
Plywood sheathing is installed so that the 8’ dimension of the plywood crosses the rafters or joists and the 4’ dimension parallels the rafters or joists. The sheets of plywood are then staggered much like ?
a brick or block wall.
Book 29 Ventilation Techniques -
Dicing is ?
a technique used to cut 1” x 4” or 1” x 6” solid, spaced, or diagonally sheathed roofs. Dice cuts are made parallel to rafters with no concern to locating rafters
Book 29 Ventilation Techniques -
“H” clips are?
“H” clips are metal clips used to hold the butted ends of plywood together. “H” clips are common on pitched roofs.
Book 29 Ventilation Techniques -
A head cut is a cut made through the roof decking that is made __ to rafters. A head cut is used to locate rafters.
perpendicular
Book 29 Ventilation Techniques -
The removal of sheathing is enhanced by a “J” hook motion with an appropriate tool (____)
pick head axe
Book 29 Ventilation Techniques -
It is not practical in most cases to remove cut plywood from a roof due to the method in which the plywood is nailed to the roof rafters. The best alternative is to louver the plywood. Once all 4 cuts are complete, use a rubbish hook and push down on the near side (__________) and pull on the far side. This method is used with the center rafter louver technique.
(the side closest to your ladder)
Book 29 Ventilation Techniques -
Nailing blocks are usually made from a 2” x 4” laid flat between rafters to provide a nailing surface for the edge of the plywood sheathing. Since the plywood normally used is 4’ x 8’ in size, a nailing block will usually be found every ___ feet.
4 feet
Book 29 Ventilation Techniques -
A _____ is a single cut made through the roof decking, the same width as the chain saw blade. Although not as effective, the kerf cut can be used as an alternative to using the smoke indicator hole.
kerf cut
Book 29 Ventilation Techniques -
A ____ is a small triangular piece of roof covering (composition), which is removed from the roof to expose the roof sheathing. A ____ is used to determine sheathing type and roof composition thickness.
plug cut
