Studying the Impact of Positive Pressure Ventilation (PPV) During Fire Attacks

This fire safety research project seeks to provide fire service with baseline for deciding when and when not to use PPV.

Increasing the fire service’s functional knowledge of PPV impact under specific conditions

Positive Pressure Ventilation (PPV) is a firefighting technique that involves the use of high-powered ventilation fans to remove smoke, heat and other combustion products from a burning building so firefighters can perform tasks within the structure in a more tenable atmosphere.

No one tactic—PPV, horizontal ventilation or vertical ventilation—will work in every scenario. Each fire event is unique, with its own complex range of variables. Understanding the fire environment, with an emphasis on ventilation-limited fire dynamics, can help firefighters choose the right tactic for a given situation.

To help inform such decisions, the PPV fire safety research project looked at nine key variables: 1) house geometry; 2) house construction; 3) fuel loading; 4) fire department arrival time; 5) tactical choices; 6) hose stream flow rates; 7) fan manufacturer and model; 8) fan placement; 9) inlet/exhaust locations.

“Previously, we’ve examined two firefighting tactics—horizontal and vertical ventilation. This fire research gives us the third component—positive pressure. This will be the only set of fire experiments in similar structures that have ever tied the three of those together.”

- Steve Kerber, Director, UL Firefighter Safety Research Institute (UL FSRI) 

Fire science experiments were conducted under controlled test conditions on realistic structures.

The structures used in the study were representative of common single-family homes found throughout the United States: a single-story ranch-style home and a modern, two-story open floor plan house. Both incorporated wood frame construction so that the results could be used to develop tactical considerations for fighting fires in residential structures.

Researchers performed three sets of experiments:

  1. Ventilation-limited room experiments were conducted under a cone calorimeter hood to evaluate the energy release rate as it compared to the fuel load in a furnished room and an over-furnished room with the same ventilation opening.
  2. Cold flow experiments were performed prior to full-scale fire tests to establish a baseline of how positive pressure fans affect the airflow in residential structures.
  3. Full-scale fire experiments fell into three categories:
    1. A set of 15 experiments in the single-story structure testing the impact of PPV on fire dynamics
    2. An additional 10 experiments conducted in the two-story structure
    3. 2 smoke removal experiments conducted in the single-story structure to assess the effectiveness of systematic versus non-systematic smoke removal using PPV

 

Positive Pressure Ventilation from UL FSRI on Vimeo.

 

Relevant Resources

RESOURCE #1: Effectiveness of Fire Service Positive Pressure Ventilation on ULfirefightersafety.org

RESOURCE #2: Fire Service Report

RESOURCE #3: UL FSRI - Technical Report

RESOURCE #4: Positive Pressure Attack - Online Training

 

Fast Facts

  • Scientific, full-scale fire testing in modern single-family homes studies the impact of using PPV fans during fire attack to increase firefighter safety and knowledge.
  • This research is led by the UL Firefighter Safety Research Institute (FSRI) with input from a technical panel comprised of fire service personnel from around the world.
  • Funding support came from the U.S. Department of Homeland Security Assistance to Firefighters Grant Program, Fire Prevention and Safety Research and Development Grant.