Screens block air by HOW MUCH during ventilation?

[fullback36]

Was asked a question the other day and can't find the answer anywhere. Its been driving me crazy that I can't find the answer so I thought I'd thow it out here:

Does anyone know how much that screens in a window will block airflow during ventilation operations? I'm looking for a percentage. For some reason it seems like I've heard 75-80% of the air is blocked by the screen, but I can't verify it anywhere.

Thanks for satisfying my curiosity!

[BKDRAFT]

I have always been told up to 70%.

[battlecomedown]

I've been told it's up to 50%. I believe that may come from the DelMar book. If you pop the screen out, it blocks 0%.

[MemphisE34a]

The correct answer is a great enough percentage that if you are opening or taking the window to ventilate, you need to remove the screen as well.

[GeorgeWendtCFI]

The correct answer is a great enough percentage that if you are opening or taking the window to ventilate, you need to remove the screen as well.

Watch this, Bob. I love playing this game.

Why wouldn't a FF want to remove the screen?

[cap6888]

Ran a call one time and when we got there, the citizen advised they came and found that there was a fire in their home. Turns out there was a fire in an upstairs bedroom which had burned itself out. One of the windows had been open with the screen still in place. There was enough soot and other by products that had clogged the screen enough to cut out the oxygen supply. Weirdest thing I had seen.

Stay Safe

[owenscott]

Book says 50% here in FL. (IFSTA), although i was told in prior training it was up to 80% .. got it wrong on my test.

[FWDbuff]

Was asked a question the other day and can't find the answer anywhere. Its been driving me crazy that I can't find the answer so I thought I'd thow it out here:

Does anyone know how much that screens in a window will block airflow during ventilation operations? I'm looking for a percentage. For some reason it seems like I've heard 75-80% of the air is blocked by the screen, but I can't verify it anywhere.

Thanks for satisfying my curiosity!

I don't know. I follow the (late, great) Tom Brennan "school of thought" of window ventilation: If you take out a window, make a door out of it."

(translation: everything goes. Glass, sash, everything. Including the screen.)

[jjcortese]

Had a living room fire last evening... same thing the widows were open and the fire burnt itself out... all that was left of the couch was the springs and a little wood...

Ran a call one time and when we got there, the citizen advised they came and found that there was a fire in their home. Turns out there was a fire in an upstairs bedroom which had burned itself out. One of the windows had been open with the screen still in place. There was enough soot and other by products that had clogged the screen enough to cut out the oxygen supply. Weirdest thing I had seen.

Stay Safe

[cap6888]

Glad to know that I am not crazy. I was thinking it was just my bad luck when I was in a dry spell.

Stay Safe

[mcaldwell]

Watch this, Bob. I love playing this game.

Why wouldn't a FF want to remove the screen?

Cuz you'll let the bugs in...

[erik3911]

50% is what i've always been told and taught. I guess the point is it's ALOT! and if you need to get smoke out quick you need the screen out! Or better yet if in doubt take the whole window!

[ScareCrow57]

Actually, it will depend on the size of the mesh in the screen. But why would you care?

[Jonnee]

Book says 50% here in FL. (IFSTA), although i was told in prior training it was up to 80% .. got it wrong on my test.

Were you taking the test on what was in the book or what every tom, dick and hairy had told you? Test are written from the text book and not from heresay.

FWD, that is the meathod we employ with windows, take it all.

Scarie crow what would you know about it? Youse guys have screens on the trailers?

Can't wait for the lafireeducatorgod to chime in.

[owenscott]

Were you taking the test on what was in the book or what every tom, dick and hairy had told you? Test are written from the text book and not from heresay.

My guess is that most training in the classroom is from a book .. i guess it was different book .... since the every tom, dick, and harry was the instructor in the previous class i took.

[CrnkB8]

Whether it's 50%, 70%, 80%, etc., it's an obstruction and it needs to be REMOVED if you want to efficiently and effectively ventilate a room and/or structure.

[DennisTheMenace]

Why wouldn't a FF want to remove the screen?

To keep the bugs out of the fire?

[DennisTheMenace]

If ventilating during the fire, the screen must go. If just airing things out during overhaul, the screen can stay if it was not yanked out during ventilation operations.