Ventilation Flashcards
According to book 29, when performing positive pressure ventilation, removing window screens will increase efficiency by how much?
50% more effective
According to book 29, concentrates of carbon monoxide can easily reach how many ppm during overhaul?
500-1200 ppm
What are the 4 objectives of ventilation?
- save lives
- assist in firefighter access
- control horizontal spread of the fire
- reduce possibility of flashover or backdraft
What is a kerf cut?
Single cut the diameter of the blade through the decking
How many inches inside of purlins should cuts be made to avoid metal hangers?
4-6”
According to book 29, plans for ventilation operations should begin by doing what?
Identifying the direction contaminants must travel to exit the area
Where is the blower placed when performing NEGATIVE pressure ventilation?
INSIDE the structure
Positive pressure ventilation is how much more effective than negative pressure?
2 times
Positive pressure ventilation is most effective when the exhaust opening is what size of the entrance opening?
3/4 to 1 3/4
During positive pressure ventilation, what is an indicator that the exhaust opening is not large enough?
Exhaust odor in the area that needs to be ventilated
Positive pressure ventilation is effective against winds of what speed?
25 mph
When using blowers in series, what blower shall be placed in front and how far from the entrance? How much more effective does the front blower become?
Large blower in front
2 feet from opening
10% more effective
What concentration of CO can be fatal in less than 1 hour?
4000 ppm
Positive pressure should never be used in place of what?
SCBA in hazardous atmospheres
According to book 29, what is the key to safe and effective vertical ventilation?
Knowledge of rafter type and direction
When is a center rafter cut used?
When cutting plywood. Used to create largest hole with fewest cuts.
Can also be used to cut a strip on roofs using 1”x6” sheating
What are H clips and what type of roof are they common on?
H clips are using to join the butted ends of plywood together
Common on steep pitch roofs
What method is used to remove decking once it has been cut?
“J” hook
What should constantly be evaluated during roof cutting operations?
Risk vs gain
What cut is used to determine sheating type and thickness of roof composition?
Plug cut
What is the difference between a score cut and a skim cut?
Skim cut cuts through decking
Score cuts through composition but not decking
According to book 29, smoke indicator holes should be placed where and how often?
Along the path of egress every few yards
Turbine ventilators are how much more effective when the are spinning?
30%
When cutting a 45 degree inspection cut, how far should you extend the cut after rolling the rafter?
6-10”
