Gav:
but incredibly dangerous to a firefighter,
and it's called a backdraft.
- Man: Open it up. - Backdraft initiated.
Dan:
- Whoa! - Whoa!
God!
Probably one of the most terrifying videos that I've shot.
'Cause it leads you to imagine,
you know, what could happen in real life.
Just to see smoke coming out of there one second.
The next second, there's huge explosion.
We once again put the Phantom
in an incredibly dangerous position.
Whoa!
( both sigh )
We should really stop doing that.
But once again, it survived.
Dan:
that seemed to be a bit cooked, but the Phantom was okay.
One of the most interesting shots, I thought.
was when all the marshmallows, they all got knocked
just from the force of the explosion.
So it could easily blow you off your feet.
Dan:
I feel like a lot of the time when we're doing an intro to a video,
we're stood somewhere quite nice and comfortable
and then we go on to do the experiment.
That was the most stressful intro I've ever been a part of.
Not gonna lie, in the intro I was trying to be all casual and cool.
Like, "Yeah, yeah, yeah."
Like, trying to make a gag about how it was cold outside.
I was like, "I've gotta get out of here." It was just so hot.
Quite cold outside, so I'm going to warm myself up a little bit.
I think I'm warm enough, actually.
- All right. Oh, it's pretty hot! - Let's head outside.
I came out, and I was just like, "Holy cow."
Yeah, I had the cameras roll right after we got of there
so we could talk about what it was like
to be inside a burning room with a rollover on the ceiling.
Okay, so we just finished the intro to part one.
I mean, if you're gonna learn to do an intro
in one take or two takes, I feel like
-
just 'cause it was getting so hot
and stood back up to do the second take.
But obviously you sort of retain a lot of the heat
-
And the end of the second take,
I felt like the last ten seconds of that just got so hot.
The air I was breathing was hot.
My shoulder-- my left shoulder boiling.
Dan:
Like, it's still hot.
I felt your shoulder here. This part is still warm.
My actual like skin through all those layers is still, like, hot.
That was an experience.
All right, here's one of our wide shots.
It sort of had the boomiest wide that we had.
Um, and using your very technical marshmallow sticks,
we can figure out the speed
of this backdraft at its fastest.
Yeah, so I think I'll start timing
- past this one to this one. - Marshmallow one.
Gav:
- Dan:
So at our shooting frame rate of 1,000,
it went from here to here in 145 frames.
That's five feet.
The speed was 35 feet per second.
- So that's 23 miles an hour. - Yeah.
Which is sort of Olympic sprinter speeds.
You have to be literally an Olympic sprinter.
It would be a real dramatic scene
running in front of a backdraft.
You'd have to already be at full tilt
going that way at this point to not get hit by that.
And then it sort of slows down as it gets further along.
I'd say that's the fastest point
that we can measure on this.
Dan:
So you've seen it in action,
but to find out more about what causes a backdraft,
we spoke to Fire Chief Ken,
who's... there.
There he is, yeah.
We're here with Chief Ken Bailey
from Travis County Fire Rescue.
- Good to see you guys. - Hello.
- That was a good handshake. - That's a solid handshake.
That is a solid handshake, yeah.
So, what exactly is a backdraft and how does it work?
So, a backdraft is where
all the contents are started on fire,
and then all the oxygen is consumed
in a sealed container.
What ends up happening
is we reintroduce oxygen
and we have a rapid explosion of the gases
which were the products of combustion.
And how often would that happen in normal firefighting?
You know, most people go a career without seeing it.
- So it's a very rare occurrence. - Right.
- But a very sudden and dangerous one. - Exactly.
I heard somewhere that you have less time
to get out of a house fire now.
So, back when our parents had furnishings in the house,
it was probably made of cotton or wool,
and those will only let off so much heat over a certain period of time.
The heat release rate on those were different.
And the products that we buy today,
they're cheaper, they're Styrofoam.
Look at it as solid fuel.
And so the heat release rate
is much, much faster on that.
It very quickly consumes the oxygen.
If the home was sealed,
and then the fire department shows up,
they open the door, and we have that
introduction of oxygen in that sealed compartment,
it gives us the challenge of the potential backdraft.
I was just blown away when we were in there doing our intro
just how hot you still feel through all the gear.
- Dan: I'm still cooling off now. - Gav: Yeah.
It was like half an hour ago. I'm, like, still warm.
And with, like, a beard, which I wouldn't have
- if I was a firefighter. - Non-regulation.
The seal on my mask was letting in hot air, too.
So that was-- I've got-- think I'm gonna shave this off before we go back in.
Next time you come back, you should just shave,
like, a strip for the gas mask.
So, say I'm just a person in the house,
my house has caught fire, I called the fire department.
Is there any state that I can leave my house
that's safer from backdrafts
or shall I just get the hell out of there?
Getting out of the house is the most important.
We would much rather you burn your house down and save your life
than try to stay with it or delay 911 by--
That's one of the problems we have, is people will--
will think, "Hey, we can handle this situation."
And then that delays a call to 911,
and then when we get there, it's a much larger fire than it needed to be.
So if you're in a room with all locked doors and there's a fire door,
and there's a window, and there's a fire,
how should you get out?
How's the best way to get out safely?
So if you're in an interior corridor
and you're trying to make it through the fire area,
the area that's involved,
and you have the choice between that and a window,
I'd choose the window before the other.
All it takes is a couple of breaths of that carbon monoxide
and hydrogen cyanide and some of the other products of combustion,
and your chances are that you won't make it to the door.
We tried to contact a lot of people
to get this simulated
and you guys are one of the very few people
who said that you'd be up to recreate a backdraft.
And you actually did it,
so we're extremely grateful that you could help us out
- and make this video with us. - Yeah, very much, Ken.
- That was really informative. - Thank you. It was our honor.
- Also scary, as well. - We appreciate it.
All right, back to you, Gav and Dan.
Thanks, us.
Now, very few people will come into contact
with a real, full-sized backdraft like that.
- Thank goodness. - But there is a much smaller version of a backdraft
that people might be familiar with.
So why don't we go outside and do an experiment?
- All right. - All right.
You know, Dan, I'm really glad we film this in winter.
Yeah, it's nice, isn't it? Good barbecue weather.
Nice time for a barbie.
- Yeah. - So, using what we've learned,
you think you can create a mini backdraft with this?
- I think so. - All right.
I'll set the scene. It's the summer.
It's not raining. Got a nice, hot barbecue.
It's been on for awhile. Hot coals.
And we got our chicken.
It's gonna be covered in oil,
'cause that's how you cook chicken, isn't it?
If I just introduce the fuel--
so this is like the wood in the back of the container.
I'll just pop that on the thing.
- Oh, you can tell it's already hot. - Yeah, it's already hot.
- Immediately lit up. - Then I close this down, shut the flames down,
and then when I reintroduce the oxygen...
it should pop out.
- Very nice. - See that?
That was great.
- Dan:
Dan:
- Gav:
Gav:
The smoke's kind of getting sucked back around.
Dan:
Gav:
- Dan:
for a second there. Look at that.
Dan:
Gav:
Dan:
Gav:
Dan:
and then allowing the fuel to burn again.
Gav:
Dan:
'cause it had been starved of oxygen.
Gav:
that's gone out as being out, really.
Dan:
So that was sort of a medium backdraft.
This time I'm gonna skip the chicken out
and just pretend I'm some sort of Muppet
who's never used a barbecue before.
"Oh, looks like it's going out!"
So I'll put a bunch of fuel on it, which is this oil here.
You got a message for anyone watching at home?
Uh, probably just, "Don't do it"?
Kids, just don't-- don't do it.
Don't try at home.
- Oh, it's gonna-- - I know.
- I'll cover that up. - Gonna be colossal.
- Are you nervous? - Nah, I'll be all right.
- All right. - Tell me when you're ready.
- Ready. - Here we go.
Whoa. Potentially delicious.
Dan: "Po-tench."
Gav:
Dan:
Full-- just an oil meal.
Just eating some oil.
-
That was significantly bigger.
Dan:
behind a waft of pure fire there.
Gav:
Look at that. It's dragon smoke.
- Dan:
Dan:
-
Dangerously beautiful that one.
Dan:
Gav:
That's your "I've just singed my eyebrows" face.
Dan:
More fuel in them than in the oil.
Gav:
( both laugh )
I really enjoyed that episode. We got some good footage.
- It was very informative. - Oh, totally, yeah.
Also, don't try the experiment at home.
- It's quite dangerous. - That it is.
Hopefully, you enjoyed that episode.
Feel free to subscribe to the Slow Mo Guys,
and make sure you check out other episodes
from "Planet Slow Mo."
- What? - Nothing.