Dave wrote:
On Fri, 12 May 2006 14:36:37 GMT, Mys Terry
said:


Then my answer is that it doesn't need to be quantified at all,

Reminds me of something someone once said about exams in law school--if you
can't answer the question asked, answer the one you wish had been asked
instead.

???


A bit too abstract for you perhaps. I'm not sure I can say it more
concretely, but trust most readers will understand.


All part of the bullsh*t and lying training necessary for a successful
lawyer.

Dave wrote:

On Thu, 11 May 2006 22:32:22 GMT, Mys Terry
said:

There are few things worse on a boat than having a fire at sea. I'm not entirely
sure that there is anything worse.

No dispute there. Merely pointing out that the initial inquiry was not
whether spontaneous combustion is a risk, but asking that that risk be
quantified.

OK - you keep going on about this when it has already been answered.
If you don't consider the risk of fire a large risk then you don't
need to worry about spontaneous combustion.

In any case, the specific inquiry was about the possibility of rags
contaminated with linseed oil spontaneously combusting. Yes it
happens if precautions are not taken. It is a real risk.

A pile of rags or paper towels soaked with linseed oil can under the
proper circumstances actually start burning without warning, leading
to the manufacturer's warning that all oil-soaked rags should be
stored under water in a covered, metal container, or washed before
storage or disposal.

From a document called
" Fire and Explosion Investigation - Spontaneous Combustion of Drying
Oils as a Fire Cause" January 2000

There are three conditions
which are important in the spontaneous ignition process. These a (i.) rate of heat generation, (ii.) air supply
and (iii.) insulation properties of the immediate surroundings. A loosely packed pile of drying oil soaked
cloths may spontaneously combust whereas a tightly packed pile or a single cloth on a clothes line will not. In
the case of a single cloth on a clothes line, although there is sufficient air supply to accommodate oxidation,
any heat generated will be carried off quicker than it is formed.

Investigation of a spontaneous combustion fire is very difficult due to the fact that there are no significant fire
residues left by this process. Thus, when flaming ignition occurs the chemical detection of residues of the
preliminary material may be impossible. In the investigation of a suspected spontaneous combustion fire there
are a number of diagnostic signs to look for. The major one being the presence of more fire damage to the
middle of a material mass than around the edges. In spontaneous ignition the most severe fire damage will
most often be in the centre of the fuel mass and in very large masses there may also be several separate
pockets of smouldering which may lead to several points of origin, ....
Another indicator of whether or not a fire was caused by spontaneous combustion may be
its behaviour when suppression of the fire is attempted. Initial attempts may only result in momentary
suppression of the flames followed by re-ignition.

This is important when you want to put out the fire - it isn't the
same as a normal fire where you can just wet down or foam the outside
of the pile.

Even in very small amounts, such as grams or ounces, these oils have been documented in laboratory
experiments to result in the spontaneous ignition of their support materials. In these tests the support
materials had a large surface area and were reduced to small volumes by being placed in a pile rather than
being spread out.
It was reported that a single rag the size of a handkerchief, which had been dampened with one of these drying
agents containing modified linseed oil, can burst into flames within 6-8 hours after exposure to the air. Also
the fire can continue to burn for an hour or more after ignition...

Tests carried out by
the Center of Forensic Sciences and the Ontario Fire Marshal’s Office confirmed this, They placed boiled
linseed oil on cotton rags and placed them in large waste containers at a temperature of 16-18°C. Smoke and
acrid odours were produced within one hour of the start of the test with flaming ignition produced 4-5 hours
later.

Some of the References for this article included

(1.) Abraham, C.J. A Solution to Spontaneous Combustion in Linseed
Oil Formulations. Polymer Degradation and Stability. 54: 157- 166.
1996.

(2.) Bertsch, W., Holzer, G. and Sellers, C.S. Chemical Analysis for
the Arson Investigator and Attorney. Huthig. 1993,

(3.) Underdown, G. W. Practical Fire Precautions. Gower Press, 2nd
edition, 1979.

(4.) http://www.interfire.org/res_file/fseab_si.htm This link doesn't
work as listed, but if you go to http://www.interfire.org/ and search
on linseed oil, the section listed will come up as one of the options.

(5) http://www.arson-codes.com/spontcom.htm This link doesn't work
anymore, but if you go to the arson codes website and select Reports
and Articles, the last article in the list is "Spontaneous Combustion
Explained" which says

Cotton rags soaked in linseed oil are very susceptible to spontaneous ignition. This is because the reaction of oxygen and linseed oil (oxidation) is fairly rapid and evolves considerable heat. Spontaneous ignition of the cotton rags can be prevented by restricting the amount of oxygen reaching the rags (placed in sealed metal container) or by providing sufficient ventilation (hanging on a clothesline) to quickly dissipate the heat.

RosalieAnn Figge Beasley, C.I.H.
retired - formerly MOSHA Consultation

"Dave" wrote in message
...
On Fri, 12 May 2006 14:36:37 GMT, Mys Terry
said:

Then my answer is that it doesn't need to be quantified at all,

Reminds me of something someone once said about exams in law school--if
you
can't answer the question asked, answer the one you wish had been asked
instead.

???

A bit too abstract for you perhaps. I'm not sure I can say it more
concretely, but trust most readers will understand.

Gee Dave, even I understand. :-)

--
"j" ganz @@
www.sailnow.com

Dave wrote:

On Fri, 12 May 2006 16:54:24 GMT, Rosalie B.
said:

It is a real risk.

[Throws up his hands in disgust.]

Well I gave you references and also times and quantities. What do you
want? Some kind of guarantee that one oil soaked rag wadded up in the
corner will burn the boat to the waterline in 5 hours?

Years ago...I watched a guy pour liquid oxygen into a small container.
He then added motor oil. Before he could rig the heavy weight, on a
shaft held up by a pin, to drop into that container...I saw him rapidly
pull his head back and twist it. At that point the mixture exploded.
He was wearing an outfit that looked like what the bomb disposal guys
wear now a days so seemed to have escaped relatively unharmed, perhaps
he's deaf in one ear, who knows.

Hydrocarbons and oxygen...it's a mixture to drive you...

Steve Thrasher wrote:

Years ago...I watched a guy pour liquid oxygen into a small container.
He then added motor oil. Before he could rig the heavy weight, on a
shaft held up by a pin, to drop into that container...I saw him rapidly
pull his head back and twist it. At that point the mixture exploded.
He was wearing an outfit that looked like what the bomb disposal guys
wear now a days so seemed to have escaped relatively unharmed, perhaps
he's deaf in one ear, who knows.

Hydrocarbons and oxygen...it's a mixture to drive you...

Liquid oxygen is indeed powerful stuff. Did you know that asphalt is
flammable when exposed to it? The pads that those tanks sit on have
to be of concrete.

However it is unlikely that you will have Lox on a sailboat.

Roger Long wrote:
We all grew up hearing about the danger of oily rags. It was linseed
oil they were talking about, not motor oil. Now that I (hopefully)
will be rubbing oil on teak for the rest of my natural life, I expect
to producing a lot of these little incendiary bombs.

How much of a danger are these left over rags? Is it something that
happens just once in a blue moon when a bunch are left in the corner
of a shop for a long time in hot weather? If the phone rings and I
forget to take one to the dumpster, is it "Good by" boat? If I do
toss them in the dumpster, am I at risk of starting a big fire in my
favorite marina or boatyard.

Is there an approved way of storing or disposing of linseed oil rags?

Inquiring mind wants to know.

I was working on re-finishing a table and tossed the rag on the
workbench, the next day funny smell from garage and found that
that rag and started burning the bench, the rag and bench was too
hot to touch and you can still see the burn markes today.
Of course it did not help that I was in TX in the
summer time and the garage gets to be like 150+ ................
Now when done with rags I throw them outside inside this metal
container.

Roger Long wrote:
We all grew up hearing about the danger of oily rags. It was linseed
oil they were talking about, not motor oil. Now that I (hopefully)
will be rubbing oil on teak for the rest of my natural life, I expect
to producing a lot of these little incendiary bombs.

How much of a danger are these left over rags?
...

I found this link, which include (about a third of the way down) a
good discussion of the issue.

http://www.woodworkersjournal.com/ez.../webreview.cfm

The oils that are dangerous are "drying oils," in particular nut oils
such as Linseed, Walnut, and Tung, while non-drying, such as canola,
corn, peanut, motor oil, etc. do not spontaneously combust.

One claim was that pure tung oil oxidizes so slowly that it is not a
danger, but that some "tung oil finishes" are mostly linseed, and thus
are extremely dangerous.

Personally, I've avoided even having linseed on the boat, having seen
the results of spontaneous combustion a few times. My previous boat
had a lot of gorgeous teak in the cockpit (seats, grate, etc) and I
went through the various stages of oiling and various finishes.
Finally, I settled on washing once a season with Washing Soda, which
restores the natural look for a few weeks, and otherwise letting it
turn grey.

My current boat has not an inch of wood on the exterior.

Mys Terry wrote:

Spontaneous combustion seems like magic, but it really isn't. I once negelected
to empty a partially full bag of clippings on my lawnmower. Later that evening I
went into the garage to get something and smelled that smell. The grass in the
bag was smoldering and HOT with wisps of smoke and steam rising from it. You
don't really think of damp grass as even being all that flammable if you tried
to light it with a match.


Terry & Skipper, Clearlake Texas

Didn't farmers lose their barns from hay smouldering in the loft?
i believe lots of ventilation was required.

Don White wrote:

Mys Terry wrote:

Spontaneous combustion seems like magic, but it really isn't. I once negelected
to empty a partially full bag of clippings on my lawnmower. Later that evening I
went into the garage to get something and smelled that smell. The grass in the
bag was smoldering and HOT with wisps of smoke and steam rising from it. You
don't really think of damp grass as even being all that flammable if you tried
to light it with a match.


Terry & Skipper, Clearlake Texas

Didn't farmers lose their barns from hay smouldering in the loft?
i believe lots of ventilation was required.

Yes a friend's barn burned down when they had just harvested. They
lost the building and everything in it - fortunately no people or
horses or cattle were harmed.