The fires.

[terryc]

On Thu, 12 Feb 2009 00:42:27 -0800, kreed wrote:

If you have a petrol / diesel / LPG powered generator used for running
a fire fighting pump, wouldnt it be at risk of stopping / misfiring /
losing power, just when its needed, if the available oxygen is
depleted by fire ? or "choked" from intense smoke ?

Possibly. AFAIUI, the problem for humans is not the abscence, but the
reduction in oxygen in the air. 21% oxygen is the normal level with some
people suffering breathing problems when it drops as low as 15%.

I suspect a motor would probably just act as if it was choked. Caveat,
they are either broke or working in my limited skills.

Would some sort of "air supply" be practical in this case ? Just another
possible thing to consider in planning a fire protection system.

I do not know how critical continuous pumping would be when the firefront
is passing. My understanding is that you want to wet down prior and have
a bit of water on the roof and in the gutter to extinguish smaller
embers/burning leaves, burning twigs, etc when they land on the roof.

When the fire front as passed, you would most likely want the sprays to
continue, but also be able to use fire houes firstly on any part of the
house that is alight, then move wider a field to sheds, etc. So
easy restart would be important.

 

[terryc]

On Thu, 12 Feb 2009 18:44:57 +1100, Sylvia Else wrote:

I'd go for compressed air, myself. Pure oxygen's toxic at atmospheric
pressure.

Not to mention that leaking oxygen makes a burning match a flaming
torch.

 

[Sylvia Else]

Rheilly Phoull wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:gn0k1c$cqk$1@aioe.org...
Clifford Heath wrote:
terryc wrote:
On Thu, 12 Feb 2009 16:02:44 +1100, Clifford Heath wrote:
Umm how fast does a bad smelling fart spread?
Ok, point taken... some significant fraction of 342m/s I'm
guessing ;-)

AFAIUI, it isn't just about the oxygen disappearing, but the percentage
of
oxygen dropping (normal 21% to 15% for problem to appear) and the
increasing prescence of carbon monoxide. My 2c is that if there is
smoke,
then there is incomplete combustion and likely to be significant carbon
monoxide.
Ok, that'd be a problem even in the presence of oxygen.
CO poisons your haemoglobin. Need to ensure that you aren't
at the bottom of a gully where it'll flow in I guess, and
having emergency oxygen would help somewhat.
I'd go for compressed air, myself. Pure oxygen's toxic at atmospheric
pressure.

Sylvia.

You may want to check that Sil

Nup. I'm sure.

But if you don't believe me

http://en.wikipedia.org/wiki/Oxygen_toxicity

Sylvia.

 

[Clifford Heath]

terryc wrote:

Possibly. AFAIUI, the problem for humans is not the abscence, but the
reduction in oxygen in the air. 21% oxygen is the normal level with some
people suffering breathing problems when it drops as low as 15%.

Possibly true, though the partial pressure of oxygen at 10,000
feet (lowest altitude where some folk start, after a day or more,
to experience altitude sickness) is the equivalent of 12% (since
the atmos. pressure there is 60% of sea level).

I doubt that problems from low oxygen start at 15%. In a short
duration event, I'd guess more like 8%.

Clifford Heath.

 

[terryc]

On Thu, 12 Feb 2009 22:53:16 +1100, Clifford Heath wrote:

I doubt that problems from low oxygen start at 15%. In a short
duration event, I'd guess more like 8%.

The problem with your lower figures is that you are thinking healthy
people.

 

[K Ludger]

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:gn0vdt$n13$1@aioe.org...

Rheilly Phoull wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:gn0k1c$cqk$1@aioe.org...
Clifford Heath wrote:
terryc wrote:
On Thu, 12 Feb 2009 16:02:44 +1100, Clifford Heath wrote:
Umm how fast does a bad smelling fart spread?
Ok, point taken... some significant fraction of 342m/s I'm
guessing ;-)

AFAIUI, it isn't just about the oxygen disappearing, but the
percentage of
oxygen dropping (normal 21% to 15% for problem to appear) and the
increasing prescence of carbon monoxide. My 2c is that if there is
smoke,
then there is incomplete combustion and likely to be significant
carbon
monoxide.
Ok, that'd be a problem even in the presence of oxygen.
CO poisons your haemoglobin. Need to ensure that you aren't
at the bottom of a gully where it'll flow in I guess, and
having emergency oxygen would help somewhat.
I'd go for compressed air, myself. Pure oxygen's toxic at atmospheric
pressure.

Sylvia.

You may want to check that Sil

Nup. I'm sure.

But if you don't believe me

http://en.wikipedia.org/wiki/Oxygen_toxicity

Sylvia.

maybe how its applied:

http://msds.chemalert.com/?id=21&file=0010678.pdf

 

[ian field]

"Clifford Heath" <no@spam.please.net> wrote in message
news:49937CCD.9060503@spam.please.net...

terryc wrote:
It is clear that there has been fires of varying intensity in different
places. For some of those fires, you would definitely have need an
underground fire cellar, which has not been a prior recommendation.

I helped out with the cleanup in Cockatoo after the Ash Wed fires.
Behind the place I helped at, just over the crest of the hill and
set into a slight slope was a 2-storey double-brick house which an
engineer had built with a nuclear bunker under the north-east ground
floor, which was a 9" thick reinforced concrete slab on footings each
side weighing nine tonnes.

The slab was collapsed into about eight big sections, and had changed
so you could break off pieces in your hand - it was like Weetbix.
So much for his nuclear shelter.

As they left during the start of the initial firestorm, an aluminium
dingy, unpainted and stored on its side in a cutting (so mostly below
ground level) beside a steel shed, *burst into flame*.

The cement-sheet house below the road was occupied the whole time and
was untouched by the fire. Firestorms are like that, I saw the same
thing in the Adelaide hills where I'd been 3 days after the fires.

The underground bunker or dugout is the only possible thing that can
survive such a fire. They used to have multiple doors, made of wet
hessian, to allow air exchange.

It's time that every house in such an environment was required to
have one within 50 metres. Other defences too, if they're to get
insurance at the same place that other folk shop.

There appears to be evidence that many people didn't attempt to leave their
house, I'm wondering why?!

 

[ian field]

"terryc" <newssevenspam-spam@woa.com.au> wrote in message
news:4993b3eb$0$42548$c30e37c6@pit-reader.telstra.net...

On Thu, 12 Feb 2009 16:02:44 +1100, Clifford Heath wrote:


I think that TV has overstated the danger.
That is the nature of TV; idiot presenter making ludicrous comments. If
you look at the images presented and idependently assess them, then you
can see it was the full range of fires..

It's true that some folk have died in dugouts, but many many more
have survived that would have died. The oxygen in the dugout won't
selectively migrate out to feed the fire, I don't think partial
pressures work that way, not quickly enough anyhow.

Umm how fast does a bad smelling fart spread?
AFAIUI, it isn't just about the oxygen disappearing, but the percentage of
oxygen dropping (normal 21% to 15% for problem to appear) and the
increasing prescence of carbon monoxide. My 2c is that if there is smoke,
then there is incomplete combustion and likely to be significant carbon
monoxide.

In the UK one TV station news showed footage of a motorcycle abandoned on
the side of the road, the rider had only made a few yards on foot before
collapsing and dying. As far as I could see there was no signs of fire
damage to bike or rider.

 

[terryc]

On Thu, 12 Feb 2009 17:03:36 +0000, ian field wrote:

In the UK one TV station news showed footage of a motorcycle abandoned on
the side of the road, the rider had only made a few yards on foot before
collapsing and dying. As far as I could see there was no signs of fire
damage to bike or rider.

Last night, on ABC's Q&A, they related how a woman tried to walk to the
oval to join the fire trucks and didn't make it either. Again, no burns,
but she died.

 

[John G.]

"ian field" <gangprobing.alien@ntlworld.com> wrote in message
news:ewYkl.6451$4%2.751@newsfe12.ams2...

"Clifford Heath" <no@spam.please.net> wrote in message
news:49937CCD.9060503@spam.please.net...
terryc wrote:
It is clear that there has been fires of varying intensity in different
places. For some of those fires, you would definitely have need an
underground fire cellar, which has not been a prior recommendation.

I helped out with the cleanup in Cockatoo after the Ash Wed fires.
Behind the place I helped at, just over the crest of the hill and
set into a slight slope was a 2-storey double-brick house which an
engineer had built with a nuclear bunker under the north-east ground
floor, which was a 9" thick reinforced concrete slab on footings each
side weighing nine tonnes.

The slab was collapsed into about eight big sections, and had changed
so you could break off pieces in your hand - it was like Weetbix.
So much for his nuclear shelter.

As they left during the start of the initial firestorm, an aluminium
dingy, unpainted and stored on its side in a cutting (so mostly below
ground level) beside a steel shed, *burst into flame*.

The cement-sheet house below the road was occupied the whole time and
was untouched by the fire. Firestorms are like that, I saw the same
thing in the Adelaide hills where I'd been 3 days after the fires.

The underground bunker or dugout is the only possible thing that can
survive such a fire. They used to have multiple doors, made of wet
hessian, to allow air exchange.

It's time that every house in such an environment was required to
have one within 50 metres. Other defences too, if they're to get
insurance at the same place that other folk shop.

There appears to be evidence that many people didn't attempt to leave
their house, I'm wondering why?!
The current advice by the authorities is

Decide Early
1 Leave if you are unable to defend.
2 Stay if you are prepared and think you can save the house.

The stories form survivors of last Saturday are all that they found out Too
late to leave and some that did were killed on the road either directly by
the fire or in crashes in the smoke.
Reports today say the fire front moved at around 100 kms per hour in some
areas.

John G.

 

[terryc]

On Thu, 12 Feb 2009 16:55:35 +0000, ian field wrote:

There appears to be evidence that many people didn't attempt to leave
their house, I'm wondering why?!

People have the choice of going early or staying and defending their
property.

The CFA oppose compulsory mass evacuations as people had panicked and been
killed in accidents during these events.

A lot of people left it too late to evacuate. If you are going to
evacuate, you need to go early, very early in the day. Not wait until the
flames appear.

Lots of people had absolutely no warning. I understand that the fires in
Marysville were burnt and gone before the authorities found out that there
was a fire there.

Some of the fires were not natural in their spread.

The CFA are now saying that many people were just not prepared in any way
shape of form despite the warning that have been given out in the days
prior.

 

[Sylvia Else]

K Ludger wrote:

"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:gn0vdt$n13$1@aioe.org...
Rheilly Phoull wrote:
"Sylvia Else" <sylvia@not.at.this.address> wrote in message
news:gn0k1c$cqk$1@aioe.org...
Clifford Heath wrote:
terryc wrote:
On Thu, 12 Feb 2009 16:02:44 +1100, Clifford Heath wrote:
Umm how fast does a bad smelling fart spread?
Ok, point taken... some significant fraction of 342m/s I'm
guessing ;-)

AFAIUI, it isn't just about the oxygen disappearing, but the
percentage of
oxygen dropping (normal 21% to 15% for problem to appear) and the
increasing prescence of carbon monoxide. My 2c is that if there is
smoke,
then there is incomplete combustion and likely to be significant
carbon
monoxide.
Ok, that'd be a problem even in the presence of oxygen.
CO poisons your haemoglobin. Need to ensure that you aren't
at the bottom of a gully where it'll flow in I guess, and
having emergency oxygen would help somewhat.
I'd go for compressed air, myself. Pure oxygen's toxic at atmospheric
pressure.

Sylvia.
You may want to check that Sil
Nup. I'm sure.

But if you don't believe me

http://en.wikipedia.org/wiki/Oxygen_toxicity

Sylvia.


maybe how its applied:

http://msds.chemalert.com/?id=21&file=0010678.pdf

Even there it doesn't indicate that it's safe for any period at 100% at
sea level. Yet if you have a cylinder of the stuff, and are using it
during a bush fire, the only way to avoid 100% is to accept some air
from the environment. That air would contain smoke, and maybe dangerous
concentrations of carbon monoxide.

Sylvia.

 

[Mark Harriss]

Not forgetting pure oxygen would allow anything slightly
flammable to burn so fast and hot that the contents of the
room including the people would be incinerated at the
slightest spark.

 

[Clifford Heath]

Mark Harriss wrote:

Not forgetting pure oxygen would allow anything slightly
flammable to burn so fast and hot that the contents of the
room including the people would be incinerated at the
slightest spark.

Medical oxygen devices don't supply it pure. It's pretty pure
in the bottle, but it gets mixed through a regulator&flowmeter.

 

[Mr.T]

"terryc" <newssevenspam-spam@woa.com.au> wrote in message
news:4993f4c9$0$42548$c30e37c6@pit-reader.telstra.net...

When the fire front as passed, you would most likely want the sprays to
continue, but also be able to use fire houes firstly on any part of the
house that is alight, then move wider a field to sheds, etc. So
easy restart would be important.

Assuming it has not already been destroyed by the fire of course.

MrT.

 

[Mr.T]

"terryc" <newssevenspam-spam@woa.com.au> wrote in message
news:4993f54d$0$42548$c30e37c6@pit-reader.telstra.net...

On Thu, 12 Feb 2009 18:44:57 +1100, Sylvia Else wrote:

I'd go for compressed air, myself. Pure oxygen's toxic at atmospheric
pressure.

Not to mention that leaking oxygen makes a burning match a flaming
torch.

Not to mention air fills are far cheaper than oxygen, so why bother!

MrT.

 

[Mr.T]

"terryc" <newssevenspam-spam@woa.com.au> wrote in message
news:49941efa$0$42550$c30e37c6@pit-reader.telstra.net...

The problem with your lower figures is that you are thinking healthy
people.

Unhealthy people should be evacuated very early, so no real problem.

MrT.

 

[Sylvia Else]

kreed wrote:

On Feb 12, 1:04 pm, terryc <newssevenspam-s...@woa.com.au> wrote:
On Thu, 12 Feb 2009 12:35:09 +1100, Clifford Heath wrote:
The slab was collapsed into about eight big sections, and had changed
so you could break off pieces in your hand - it was like Weetbix.
So much for his nuclear shelter.
How big was the slab? If it collapsed, it sounded like the
supports/walls gave way.

I'm not worried about the changed nature of the slab,but the collapse.
the purpose is to protect life. Replacing the slab as part of
rebuilding seems sensible.

The underground bunker or dugout is the only possible thing that can
survive such a fire. They used to have multiple doors, made of wet
hessian, to allow air exchange.
I suspect that air cylinders might be required. TV carried a few comments
from people about difficulty of breathing when the fire was around and
intense fires can deplete available oxygen.



If you have a petrol / diesel / LPG powered generator used for running
a fire fighting pump, wouldnt it be at risk of stopping / misfiring /
losing power, just when its needed, if the available oxygen is
depleted by fire ? or "choked" from intense smoke ?

Fires suck in fresh air as the hot air rises. If they didn't, they'd
smother themselves. So once the fire front's passed, and if the house is
still standing, I can't imagine a generator being prevented from running.

Sylvia.

 

[L.A.T.]

This thread can now be laid to rest.
Germaine Greer has finally told us what we did wrong.

 

[Sylvia Else]

L.A.T. wrote:

This thread can now be laid to rest.
Germaine Greer has finally told us what we did wrong.

She has an unfortunate way of expressing her view (characterising us all
as arsonists), but she's not so far wrong.

As I've commented on a DT article that discussed her views, the
arsonists have merely lit fires now that would otherwise have happened
sooner or later by natural causes (or accident). It was just a question
of time.

It would be a mistake to think that arsonists are the cause, and that if
we could somehow deter people from arson, the problem would go away.
Because it wouldn't.

Sylvia.