I added the Ventilation in the name, but I will actually be touching more on P.P.A.
Was reading a post on the main page started by FETC on positive pressure ventilation. just thought I would write this.

What is P.P.A.?
A coordinated fire attack operation involving a combination of positive pressure ventilation and interior fire attack.
How does P.P.A. work?
Using the gas powered blowers to force heat, smoke, and toxic gasses to an area of lesser pressure during the initial phase of fire attack.


Advantages of P.P.A.

Removes smoke and heat
Improves visibility
Reduces property damage
Decreases the chance of Flash over
Decreases fire spread
Improves interior conditions for trapped occupants


Misunderstandings

It will (not) push fire into voids
It only pressurizes the interior of a structure, like blowing air into a balloon it will push outward until an opening is present, which then the air will follow the path with least resistance and leave through the hole.

It will (not) push fire into the walls of balloon frame construction
This is a long section and I will make another post dedicated to just this so as to present a way to prove this, with an aquired balloon frame structure, there is also an interesting find on vertical ventilation I'll throw in there.

it will cause the fire to flash over
Yes it will cause a flash over if done improperly!
There must be an adequate exhaust opening
Firefighters must wait before entering, and have the blower at their back

When P.P.A. should not be used
Victims or firefighters are near or at the exhaust opening
,
Fire is a lot like air and has the tendency to follow the path of least resistance. with the exhaust opening your pushing the fire right at them

Interior attack cannot be made safely.
there are many reasons for this one, Basement fires, compromised structural integrity, and an offensive fire attack is ruled out, are a few reasons.

Window rescues ahead of the fire are tactically utilized (V.E.S.)

When there is no adequate exhaust port
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Now, I'm unsure of your staff limitations and what tactics you like or dislike, but for the sake of motion P.P.A. is a first due engine company tactic, and takes place DURING the initial 360 before the hoseline deployment. it requires the (On-Duty, Engine, Truck) Officer or senior firefighter to make the order to pull the fan to the entry point, the officer/senior then smashes the fire room window and commands the nozzleman or other personnel to turn the fan into the structure.

By the time the officer finishes his 360, the entry team are masking up, this allows the time for the structure to pressurize and start forcing smoke,heat and flames through the path of least resistance (the window he/she just smashed out...), leaving you with clear visibility and low heat.

As you observe at the front door your nozzleman does his check for A.V.P. (not alien versus predator) Air, Volume, and pressure. and the officer opens that door and peers in looking for victims in the path of egress and for smoke lift or any other conditions that either support or abort the operation. ITS GO TIME!!!!!!

Re-iterate?

1. On scene report,
360,
Orders the attackline and the fan to entry point specified turned on, and pointed in.
Smashes window and finishes 360 shutting off utilities as he goes

2. Firefighter flushes the line checking A.V.P. and watching conditions until all are ready for entry.
officer looks in checking for victims and smoke lift or push.

3. Entry.
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Things to remember

DO NOT face the fan into the doorway until ordered.

WAIT at the least, 30 seconds before entering the structure after facing the fan into the doorway and ensuring proper aircone around entry point.

Ensure your hoseline will not displace the the fan as you deploy the hose into the structure.

THIS IS A COORDINATED EVENT!!!!!!!!!!!! cant stress this enough

Pay attention after you have knocked the fire down, it can re-ignite especially when using a fan.
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Now the actual training or drilling is upto you guys, im looking foward to input/comments/questions.

p.s. don't forget the whole.... average blower cfm of 15,000 feet to 20,000 cfm being adequate for a 5,000 square foot structure. Just know your equipment. I know it's random but the small things I didn't mention are for a reason. I believe in your skill and knowledge

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Replies to This Discussion

This tactic works well with wind-driven fires in high-rise structures. This was tested out around 2006 on Governor's Island by New York City. They would place 26" gas powered PPV fans at the bottom of the stair-well and pressurize the stair-well to keep the fire and smoke from spreading from the rooms and hallways.
We would take Wildland flagging, hang them in a room or hallway that has a vent opening leading outside like a (back)door or room window that you can open or close.
Afterward we would demonstrate by sequentially opening and closing each room vent to show that air follows that path of least resistance.
Nice demonstration without using a smoke machine or anything, we would use a balloon to demonstrate but the objects would always get in the way.


http://www.youtube.com/watch?v=wUUJ2ktNGmk

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