Ch 9 pg 240-247

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Questions and Answers

What was the initial purpose of testing positive pressure ventilation (PPV)?

To improve air quality in smoke-filled environments

To enhance the efficiency of firefighting

To reduce stack effect in high-rise fires (correct)

To increase the rate of fire containment

Which fire department expanded the use of positive pressure ventilation beyond high-rises?

Los Angeles Fire Department (correct)

New York Fire Department

Chicago Fire Department

Miami Fire Department

What negative outcome can result from improper use of positive pressure ventilation?

Longer firefighting times

Decreased visibility

Increased stack effect

Fanning smolders into a conflagration (correct)

How does positive pressure in a stairwell affect heated gas flows?

It reverses their flow away from attack crews Signup and view all the answers

What is an important factor for the effectiveness of positive pressure ventilation on the fireground?

Understanding what environmental conditions exist Signup and view all the answers

What is a potential disadvantage of using hose streams on minor fires?

They can use up water needed for fire control. Signup and view all the answers

Which factor is NOT mentioned as a drawback of using smoke ejectors and similar devices?

Need for continuous maintenance Signup and view all the answers

In which situation should hose streams be avoided due to potential safety hazards?

In areas of below freezing temperatures Signup and view all the answers

What positional distance from the window is recommended to create a venturi effect?

6-8 feet Signup and view all the answers

What is a possible risk when attempting to ventilate from the window in a commercial area?

Igniting smoldering materials. Signup and view all the answers

What angle of the nozzle pattern is identified as optimum for air flow?

30-35° Signup and view all the answers

What is one significant drawback of early mechanical ventilation methods for firefighter smoke removal?

Fans often did not fit openings correctly. Signup and view all the answers

Which of the following modes of operation is NOT typically associated with smoke-removal devices?

Creating a vacuum to trap smoke. Signup and view all the answers

What issue arises when fans are improperly fitted in mechanical ventilation systems?

They lead to a churning effect that decreases efficiency. Signup and view all the answers

What was the common use of mechanical ventilation techniques in the first two decades?

Primarily as exhaust devices for smoke removal. Signup and view all the answers

What is one advantage of positive pressure ventilation compared to negative pressure methods?

It effectively expels smoke while introducing fresh air. Signup and view all the answers

Which consideration is least critical when planning the use of PPV in a fire situation?

The status of the building's overall structural integrity Signup and view all the answers

What key factor should NOT be overlooked when using PPV?

The timing for opening and closing windows Signup and view all the answers

Which factor should be assessed to determine the effectiveness of PPV?

The location and extent of the fire Signup and view all the answers

What condition would make the implementation of PPV hazardous for victims and firefighters?

Entering through points other than where the PPV fan is operating Signup and view all the answers

What is the primary purpose of making an opening at the top of multistory structures?

To facilitate the upward movement of fire gases. Signup and view all the answers

Which architectural feature is most commonly associated with vertical fire spread?

Staircases Signup and view all the answers

What is a common feature of staircases in multistory buildings concerning fire safety?

They can extend past the top floor onto the roof. Signup and view all the answers

What is the primary purpose of leaning the door against the bulkhead at a 45° angle?

To establish a ramp for reaching heights Signup and view all the answers

Which tool is used to secure the door in place while using it as a ramp?

A Halligan tool Signup and view all the answers

How should the forked end of the Halligan tool be positioned when securing the door?

Parallel to the bottom edge of the door Signup and view all the answers

What is required for the firefighter to successfully ascend the ramp created by the door?

A running start Signup and view all the answers

What height range can the bulkhead reach above the roof level?

8 to 10 feet Signup and view all the answers

Which of the following statements about breaking skylights is true in the context of firefighter operations?

Personnel ascending the stairs need to be considered before proceeding. Signup and view all the answers

What common issue arises in most fire departments regarding the response of ladder trucks?

There is usually a delay in the ladder truck's arrival compared to the engine. Signup and view all the answers

What is an important precaution to take when providing ventilation over a critical vertical artery during a fire?

Check if the stairway is clear of personnel before acting. Signup and view all the answers

What was the main purpose of dumbwaiter shafts in late 1800s through early 1900s buildings?

To simplify garbage disposal Signup and view all the answers

How does fire typically extend in a building with trash shoots?

By finding alternative vertical pathways Signup and view all the answers

What is a significant benefit of removing the lid of a dumbwaiter shaft during a fire emergency?

It delays horizontal fire extension into the cockloft Signup and view all the answers

What role does the soil pipe serve in fire scenarios?

It indicates potential vertical fire extension pathways Signup and view all the answers

When checking for fire extension, what should be done with the soil pipes on each floor?

Feel for heat and check the base Signup and view all the answers

The danger with vertical ventilation of staircases much as with horizontal ventilation is what?

Geometry and wind direction Signup and view all the answers

Study Notes

Geometry of Ventilation

Venturi effect improves stream efficiency by positioning 6-8 feet from window or door.
In commercial settings, this distance may expose firefighters to smoldering materials, risking reignition.
A narrower stream can be used if maintaining distance is necessary for safety.

Hose Stream Limitations

Using a hose stream on small fires can deplete limited water supplies needed for control.
Avoid using hose streams in freezing temperatures; ice can create fall hazards.

Smoke Removal Devices

Smoke ejectors, blowers, and exhaust fans are effective without the limitations of hose streams.
Care must be taken regarding power supply availability and safety around explosive gases.

Positive Pressure Ventilation (PPV)

PPV can reverse heat and gas flow, aiding in fire attack via strategic airflow.
Originally used to combat stack effect in high-rise fires, has been adapted for various structures.
Must be used with care to prevent directing flames onto victims or firefighters.

Mechanical Ventilation

Mechanical ventilation can channel combustion products effectively by either sucking smoke out or blowing fresh air in.
Historically focused on exhaust techniques which were less effective due to poor sealing around devices.

Key Considerations for PPV Use

Ensure the strategy does not blow fire towards victims.
Assess all hoselines and water supply status before deployment.
Avoid using PPV if the fire is contained and well-ventilated.
Coordinate the opening and closing of windows during the operation to optimize airflow.

Vertical Ventilation Strategies

Create openings above vertical arteries like staircases for effective heat and smoke evacuation.
Skylights provide a crucial opportunity for ventilation, and caution is advised when breaking glass for this purpose.

Bulkhead and Ladder Techniques

Opening bulkheads promptly is essential once hoselines operate to manage heat and smoke.
Use of a secured ramp created by leaning a door can assist firefighters in reaching high bulkheads.

Structural Considerations

Early 20th-century buildings employed trash chutes, now often replaced by compactors.
Fires extending into trash chutes can rapidly progress to upper levels.
Dumbwaiter shafts may feature skylights that can prevent horizontal fire extension if accessed promptly.

Soil Pipe Identification

Soil pipes indicate the presence of vertical pipe arteries and can help locate fire extension points.
Checking for heat along soil pipes can provide insight into potential fire movement towards the attic.

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Description

This quiz explores the principles of geometry concerning the openings in windows and doors, particularly in commercial settings. Learn how the positioning relative to these openings can affect airflow and efficiency, specifically focusing on the venturi effect in real-world applications.