What would you think of a firefighting tool that would dramatically enhance victim and firefighter survival chances, a tool has been available for more than five decades?

The positive outcomes achieved by this tool have been researched and confirmed, using empirical and practical methods, by international fire engineering groups, fire professionals and fire departments. It has undergone critical evaluation that has resulted in a substantial amount of data. This tool has been strenuously put to the test by agencies that have attempted to make it fail under all kinds of practical and theoretical fire scenarios. As a result, fire departments of all sizes and demographics have praised the advantages that this particular tool has given them.

Unfortunately, for both victims and firefighters alike, false perceptions and a lack of training are keeping this tool from being actively used by all fire departments. Because of the traditional foundation of our fire service, many won't even try this tool. Some departments will try it, but because of the seemingly simple nature of the operation, fail to seek professional training. Departments that implement this tool without a complete understanding of its operation often experience false starts because of their lack of basic training and their expectation of failure.

Positive-pressure ventilation, or more correctly positive-pressure attack, is the method in question.

Why positive-pressure attack?

Put as succinctly as possible, we advocate the use of blowers for ventilation at the same time hose lines are put into operation. We absolutely know that lives can be saved if fire departments adopted this strategy of firefighting.

Generally speaking, vertical ventilation takes more time to provide a clear interior environment than it does to deploy the initial interior attack line and begin the fire attack. Although ventilation should be coordinated with the interior attack, the task is routinely assigned to later-arriving fire units. Changing the fire service's mind-set to accept that ventilation must be coordinated with the fire attack may seem like an insurmountable task, which leads us to the term “positive-pressure attack.”

In the context of positive-pressure ventilation, there are two types of fire departments. The first is very conventional and will not operate blowers until the fire is completely out, or those departments may not use their existing blowers at all. The second type of department is actively experimenting with a pressurized attack and may allow firefighters to enter the structure, after which they begin to operate blowers. Unfortunately, there are only a few departments in this country that have their first-arriving crews set up blowers before attacking the fire in a coordinated manner. This method has great promise if used safely and effectively.

There is nothing inherently wrong with either of the two types of fire departments. Both are probably making assumptions, based on their experience. But shouldn't we be asking ourselves why we continue to operate the way that we are? No one will argue the fact that change is difficult for everyone, but it almost nears being sacrilegious in a service so deeply entrenched in tradition.

The difference between PPV and PPA, as we see it, is that PPV takes place after initial fire attack crews have entered the structure, water has been deployed and fire knockdown is beginning. This process will always produce the same negative effects:

• As the thermal balance is disrupted, temperatures increase throughout the fire area, especially in the victim survival zone, which is the 30 inches of space above the floor.
• The lethal products of combustion are pushed down to the victim survival zone, where victims then inhale them.
• Oxygen levels at the victim survival zone decrease due to the survivable air being replaced by lethally hot and toxic gases.
• Soot is created throughout the fire area, increasing property damage.
• Firefighter safety and effectiveness decrease because firefighters are operating in an environment that would kill them without PPE.

PPA, on the other hand, has positive effects on the fireground when deployed by the first apparatus on the scene as part of the initial attack. Crews are not subjecting themselves to the physics of the fire; instead they are controlling the physics through a coordinated pressurized attack. This type of attack will produce the following positive effects:

• Temperatures in the victim survival zone decrease because hot gases are systematically removed simultaneously with an aggressive interior fire attack.
• Carbon monoxide and other lethal gases are removed from the fire area and structure instead of lowering into the victim survival zone.
• Oxygen levels at the victim survival zone are increased because of the introduction of fresh, cool air. Demonstrations have shown that if a fire has enough oxygen to be in a free burn state, adding more of the same concentration of oxygen (16% to 21%) contained in ordinary air will not spread or increase the fire spread.
• Property damage is decreased because soot-producing products of combustion are quickly removed in coordination with the fire attack.
• Firefighter safety and effectiveness is increased because all of the interior firefighters are able to see and operate in a clear and cool environment.

Convince firefighters to change

In conjunction with changing the mind-set that ventilation can and must be a coordinated operation, we also have to change how we operate. For example, blowers must not be placed exclusively on ladder trucks because they may not always be first on scene. In 1991 we placed a blower on one engine to supplement those carried on our ladder trucks. After excellent training and several fires positively demonstrated the effectiveness of PPA, blowers soon became standard equipment on every piece of structural firefighting apparatus in our department.

When we first began teaching firefighters PPA, we would present volumes of data and studies along with the practical training. It didn't take us long to realize that there was one component lacking as we tried to impart knowledge and effect change: Firefighters needed to feel in their gut that what we were saying and demonstrating made sense. More importantly than the didactic material, we realized that we had to affect the firefighters' emotional side.

One of the first emotional grips that we use is a 911 recording from an obviously distraught mother who keeps repeating that her daughter is trapped by a fire and she can't get to her because the smoke is too thick. The irrefutable fact is that the toxic products of combustion are what kill civilians and make our job so dangerous.

I don't believe we have taught a class or presented at a seminar without being contacted by a participant within a few weeks who tells a story that goes something like this:

“As we arrived there was heavy smoke and fire coming from the structure. We placed hose lines, started the blowers, ensured that an adequate exhaust was being made and then walked upright into the structure. We were able to see the interior of the structure that we were entering and made a great stop with little water or smoke damage.”

Tactical considerations

For firefighters to accept change, a specific need has to be perceived and acknowledged. Often this need for change is nothing more than the challenge of asking if there's a better way of doing something. However, change also may occur when the practical application of innovative equipment or theory results in unexpected positive outcomes.

PPA is a needed change that addresses how we attack today's structure fires. Used appropriately, PPA improves our ability to provide firefighting services and increase firefighter safety. Used inappropriately, PPA can cause unsafe conditions that may injure firefighters and increase property damage. PPA is no different than any other innovative change; it has been and should be approached with varying levels of caution.

PPA is generally able to meet tactical objectives more efficiently and effectively than vertical ventilation or the post-fire knockdown deployment of blowers in residential and small commercial buildings. Consider these objectives:

Increase victim survival

Ventilation and fire attack must be coordinated to meet this objective. PPA achieves this by providing ventilation at the same time fire attack begins. Post-fire knockdown deployment of blowers still allows the disruption of the thermal balance and lowers the lethal products of combustion to the area where victims are likely to be found, thus drastically decreasing their chances of survival. If we use vertical ventilation, coordination becomes more difficult. It usually takes less time to deploy an initial attack line and start water application than it does for the benefits of vertical ventilation to become apparent.

Search and rescue

When extinguishment is started before ventilation, crews and potential victims are subjected to conditions of high heat and obscured vision. Because the thermal balance is disrupted, any victim has little chance of survival. Not only do these conditions greatly reduce the ability of victims to survive, they also make it more hazardous for interior fire attack crews to search for and locate them. With PPA, the interior environment is rapidly cleared of the toxic products of combustion, thereby increasing the ability of firefighters to conduct search and rescue. PPA also gives the victims a greater chance of survival because the thermal balance is not disrupted.

Decrease fire spread

When post-fire knockdown deployment of blowers is used, fire spread is stopped at the time of knockdown. However, when vertical ventilation is used to clear the living quarters of structure, the fire is intentionally forced into a possibly uninvolved attic space. Incident commanders who call for vertical ventilation must determine if their use of resources in this manner is going to provide the best possible outcome. Don't forget that crews performing vertical ventilation can't directly assist with fire attack and search and rescue. PPA, on the other hand, keeps the fire venting out of either an existing opening or one that has been created, usually be breaking a window. At the same time PPA also allows more firefighters to assist in fire control and search-and-rescue operations because they are not assigned to the roof.

Decrease flashover

With the post-fire knockdown use of blowers, interior temperatures and the danger of flashover aren't decreased until knockdown has been accomplished. The same can be said for many vertical ventilation operations where crews have already made entry and started water application prior to completing ventilation.

With PPA, heat and the products of combustion are removed from the structure ahead of the advancing fire attack crews. PPA is able to decrease the potential for flashover by introducing cool air into the structure while expelling high volumes of heat and smoke, therefore keeping the temperature of combustibles below the flashover threshold. This decrease in temperature comes at the most important time, when firefighters are entering the structure. Of course, caution has to be taken that an adequate exhaust is provided for the controlled removal of the products of combustion before blowers are turned into the structure.

Advance to the fire

When blowers are used after knockdown, the interior environment isn't improved until after ventilation has been started and water application has begun. In fact, interior conditions often worsen without ventilation. Considering coordination, crews entering the structure generally do so in a shorter period of time than crews completing vertical ventilation. If this is the case, vertical ventilation may not be of much assistance to the initial fire crews as they enter the structure.

The advantage of PPA is that the interior environment is improved because the products of combustion and heat are rapidly removed as crews enter and begin their fire attack. A comparison between a SWAT team and firefighters can be made in terms of clearing a building in a systematic way. The SWAT team moves from the area of least danger to the area of greatest danger, clearing each room of threats as they go. Using PPA, firefighters are able to do the same as they enter a structure and clear the building of victims and hazards as they make their way to the seat of the fire. Our tests indicate that PPA provides three times the exiting volume from an active fire area than vertical ventilation.

Reduce property damage

Property damage in the form of smoke and water will not be decreased by the use of blowers following knockdown because the smoke and soot have caused property damage prior to the blower being put into operation. Vertical ventilation, however, will often bring the fire to into an uninvolved area, such as an attic space.

Building construction

Although there are five recognized types of building construction, each type fits into two basic categories based on how it reacts when subjected to fire. Type II/non-combustible and Type V/wood-frame react similarly and are often referred to as lightweight. Likewise, Type III/ordinary and Type IV/heavy timber or mill are referred to as conventional construction and should be considered together. The exception is fire-resistive or Type I construction.

Fire-resistive (Type I)

There is no practical means of ventilating a fire-resistive building other than using the existing building systems and designs. We may, however, assist these fire protection systems with additional coordinated pressurization. These structures are constructed of steel and concrete and provide little possibility of creating additional exterior openings. Crews must rely on either existing roof openings or breaking windows, which presents a whole new set of problems. Many of these buildings are high-rises, making attempts to ventilate them extremely time-consuming and resource-dependent.

Lightweight (Types II and V)

The roofs and floors of these buildings are built with a minimum amount of mass. Whether they're made of metal or wood, collapse and structural failure will occur quickly when subjected to fire. During several test burns conducted by various agencies, lightweight wood members begin to fail within five minutes followed by rapid collapse. If a structure is new enough to be built with a roof decking made of 7/16-inch wafer board, extreme caution should be taken. Failure of this type of material to support 100 pounds over the average boot size of 18 square inches was shown to occur within three minutes after direct flame impingement.

Early collapse also can be expected in buildings constructed of lightweight metal. If fire crews are successful in vertically ventilating these types of buildings and the operation results in direct flame impingement, they should make a rapid retreat due to impending structural failure. Incident commanders must realize that causing fire to move into the previously uninvolved lightweight area may result in a collapse that occurs in a short period of time.

Conventional (Types III and IV)

These buildings were built during the time that mass rather than angles and trusses were used to overcome gravity. These buildings are very prevalent throughout the country and were built from the late 1800s through the 1930s. The mass used to construct these buildings makes them safer for firefighting efforts than lightweight systems, but they're also more formidable and therefore more difficult and time-consuming to open.

Besides their mass, these buildings' roofs have been remodeled for decades with new layers, if not entire new roofs, added to assist with the runoff of rain and snow. Generally speaking, the time it takes to make an adequate vertical opening in these roofs is longer than it takes to extend attack lines into the structure. This being the case, the benefits of a working vertical ventilation operation are behind the curve of coordination with the fire attack.

If crews can't make adequate ventilation openings ahead of or in coordination of the attack crews, the incident commander has to weigh the benefits of using resources that would normally be assigned to ventilation to assist with other tactical operations, such as fire attack or search and rescue.

The trouble with BTUs

The amount of BTUs released from a modern fire is much higher than those of a few years ago. A pound of ordinary combustibles 30 years ago generated about 8,000BTUs. Compare that to the 18,000- to 24,000BTUs being released by a pound of today's ordinary combustibles.

This dramatic increase in BTUs can be attributed to the predominant use of synthetic material in modern furnishings and building materials. The hydrocarbon base of many of these materials makes them little more than solid gasoline waiting for the appropriate temperature to decompose through combustion and release their lethal combination of poisonous gases and extreme heat.

Although the increase of BTUs in modern fires in irrefutable, some still train recruits to begin vertical ventilation with the decade-old standard 4-by-4-foot opening and expect that to be adequate. There's no way that such an opening can compensate for the increased BTUs of the fires commonly encountered today. If this ventilation hole is too small to release adequate volumes of heat and smoke, it may be of little value except to behave as the flue of a firebox that will increase the fire's development. Couple this with the fact of an early collapse in lightweight structures, and you end up with a double-edged sword that is working against our conventional fire attack.

What to look for

Today's blowers have been designed exclusively for the fire service and have evolved to make the pressurized control of the interior environment and PPA much more effective.

The volume of air being moved by the blower is the key to PPA; therefore purchase the largest-diameter blower that will fit on your apparatus. The number-one feature that should be noted is that blowers must be carried on all structural apparatus because they must be deployed by the first-arriving company as they begin their initial fire attack. Blowers soon will be evaluated by the amount of exiting cubic feet from a test chamber and be rated against a standard specifically written for blowers used by the fire service for pressurization.

The recommended features include:

• Blowers should be gasoline-powered for a rapid deployment.
• Blowers should be shrouded to increase the amount of air entrained and therefore the amount of exiting CFMs.
• Blowers should be able to tilt up and down to increase their ability to cover an opening if the optimum distance (8-10 feet) between the blower and opening can't be achieved.
• Blowers should have pneumatic tires to facilitate one firefighter being able to maneuver it to the objective.
• The power plant of the blower should be as simple to operate as possible. The fewer switches the better.

Blowers should be capable of being operated by one firefighter. The PPA evolution demands that the first-arriving company deploy the blower and that the blower must be taken to the objective by one of the first-arriving firefighters.

The use of pressurization isn't entirely new to the fire service. The use of blowers has been studied and evaluated for decades, both in the United States and Europe. The last 12 years have been the most significant in terms of innovations that have changed products and theory. Many of these developments have been evaluated and re-evaluated by departments and testing agencies in several countries. There is now a large body of knowledge and data that can be attributed to the fire service being committed to using blowers as part of its initial attack.

Many times PPA is a more effective, more efficient and safer method to attack structure fires. A well-coordinated PPA consistently demonstrates better outcomes than either post-fire knockdown deployment of blowers or vertical ventilation.

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Kriss Garcia is a battalion chief for Salt Lake City Fire Department, where he has worked for 20 years. He is an instructor for the National Fire Academy as well as the Utah Fire and Rescue Academy. Garcia sits on the Air Movement Control Association standard review committee and is a Utah-licensed general engineer. He has an associate degree in pre-hospital care as well as bachelor degrees in public administration and education.

Reinhard Kauffmann is a battalion chief for Salt Lake City Fire Department, where he has worked for 28 years. Currently he is assigned as the fire chief for the Salt Lake City International Airport Authority. Kauffmann is an instructor for the Utah Fire and Rescue Academy. He is a graduate of the University of Utah with a bachelor's degree in science.