Deputy Chief Gary P. Morris,
Phoenix (AZ) Fire Department
Response: Our department has more than 12 years of experience in the application of PPV. All ladder companies now carry two high-volume fans. We believe in early ventilation–vertical or by PPV–depending on the situation. The incident commander determines the type of ventilation and coordinates its use. PPV is used for fire attack operations and is continued into overhaul. We have not experienced any significant adverse effect from its use.
Where PPV is the preferred option, standard operating procedures (SOPs) direct the ladder company officer to plan to use it on arrival at the scene at any working interior fire. Because of the later-arrival sequence of ladder companies at most fire incidents in Phoenix, PPV application generally occurs after interior firefighting has been initiated. In these cases, SOPs require that interior crews be notified of its intended use, for safety reasons and to coordinate details as necessary.
Positive-pressure ventilation has significant benefits to the “survival profile” of any victim trapped in a fire. Introduction of PPV improves the atmosphere, clearing out toxic gases and cooling the environment. Search and rescue is also improved; the smoke is cleared rapidly, allowing rescuers to locate victims more quickly. Also, the proper use of PPV helps to confine the fire.
Our experience reflects numerous benefits. Crews routinely report rapid reduction in heat and smoke following the proper introduction of PPV. Some have reported viewing visible fire “retreating” down hallways as the positive pressure and air volume force combustion products out of the building. The removal of smoke improves visibility for firefighters, making work safer, while also improving the survivability profile of any victims. The cooling of the interior environment also improves work conditions.
Positive-pressure ventilation during attic fires prevents smoke from pushing out of the attic space and obscuring visibility after the ceiling is pulled. In strip shopping centers (or buildings with common attics), setting up PPV fans in adjacent exposure occupancies can help to keep the fire confined to the occupancy of origin (the fire occupancy must be top vented or burned through and the ceiling opened in exposures).
Our experience has also identified several key elements that must be in place for successful PPV application. First, the earlier the application, the greater the benefits. Second, there must be an exhaust “exit” in the fire area to allow the combustion products to be removed. Third, the incident commander and sector officers should closely monitor the effects of PPV and modify operations as needed. Finally, for multistory or large or complex buildings, a “ventilation sector” should be established to coordinate all ventilation operations.
