Chapter 15 Pressurized Ventilation Flashcards
What are the two basic types of pressurized ventilation?
Positive and Negative pressure
Name four factors that are essential to effective PPV
The proper use of an entrance opening
The size and location of an exhaust opening
controlling the flow of pressurized air
and appropriate training and communication
What determines the proper distance between a blower and an entrance?
The distance necessary to seal the opening with a pressurized cone of air
When using two blowers of unequal size in the inline position to seal an entrance with pressurized air, where should the larger blower be positioned?
Approximately two feet back from the entrance opening
With respect to PPV, what is the definition of sequential ventiliation?
Ventilating specific areas in a strategic sequence that will maximize the flow of pressurized air through a contaminated area and minimize the time required for ventilation.
How can Carbon Monoxide from gasoline-powered blowers be eliminated?
By using exhaust tube extensions on the exhaust muffler
Normally, where should pressurized ventiliation begin in multiple story buildings?
Start at the lowest contaminated levels and ventilate toward the upper contaminated levels
Why can stratification be detrimental to natural ventilation operations?
The stratification of smoke and fire gases can cause the porducts of combustion to bank downward, contaminating additional areas of the building.
Name some advanteds of using PPV during overhaul
A flow of fresh, cool air will reduce heat, humidity, and the accumulation of toxic gases
When implementing PPV, is the exhaust opening created before of after the entrance?
Always before the entrance opening
What is the primary goal of ventilation?
to reduce contaminants in confined areas
How large should the exhaust opening be to maximize the efficiency of the PPV?
.75-2.0 times the size of the entrance opening
What is the key to effective PPV?
controlling the entrance and exhaust portals as well as the path of the airflow
PPV has proved effective against winds of up to how fast?
about 25 mph
Removing screens on windows can improve PPV effectiveness by what percent?
50 percent
How far can PPV be effective in a confined area?
up to 1000 ft.
Fire can generate pressures how many times greater than atmospheric pressure?
3 times greater
Cross-ventilation operations can be effective on buildings up to how many floors?
up to 25 floors
PPV can reduce CO concentrations from 1000 PPM to what?
130 ppm-220ppm
How much CO (ppm) can a single gasoline-powered blower introduce into a structure?
140ppm-160ppm
How much CO can a typical person inhale over an 8 hr period?
50ppm
How much CO, when consumed over an hour, can be dangerous?
1000 ppm-1200ppm
What levels of CO are fatal if inhaled in less than an hour?
4000 ppm
How much CFM should a blower be to be most effective?
7,000-10,000 cfm
When using PPV fans on a dumpster fire, how far away should you place the fan?
8-10 ft. away
PPV can reduce the core temp of personnel by how much during supression operations?
as much as 5 degrees
What is indicated when exhaust of gasonline powered blowers are detected?
exhaust openings are too small
