[QUOTE=kladner;527729]How does a load of trash spontaneously ignite?[/QUOTE]

Happens all the time.

Decomposition is an exothermic reaction. If there's oxygen available but the decomposing material is compacted enough, the temperatures can reach the point of spontaneous ignition.

[QUOTE=kladner;527729]How does a load of trash spontaneously ignite?[/QUOTE]That is not the Saddle Ridge Fire.

There are a bunch of different ways, here are a few:
spontaneous ignition of oily rags,
someone dumping ashes with some hot coals still in and another person dumping cooking oil,
various household chemicals getting mixed from different people (pool chlorine is a common problem,
compression of certain canisters that contain flammable gasses,
batteries getting shorted out.

[QUOTE=kladner;527729]How does a load of trash spontaneously ignite?
[/QUOTE]Given time and other conditions, bacterial action can heat organic material up to the point where inorganic oxidation can take over. Seemingly paradoxically, therefore, wetter material can present more of a hazard. As a teen, I was instructed by my farmer father to leave one particularly heavy small square bale out of the barn, well away from any structure. Normally they weigh 40-50 pounds. That one was the same size but over 100 pounds. It was from a part of a field with very dense growth of succulent weeds due to runoff from the adjacent cattle yard providing plenty of fertilization, which did not dry out much after cutting before the whole field was baled.. After a couple of days delay as it sat in the open air, I split it open in the middle. A few inches inward, the center half looked more like months-old silage than 2 day old hay. The outside looked and felt normal. The center was too hot to touch. I was not sure whether that was steam or smoke given off when I split it open. A bale like that can be the igniter for a very bad barn fire. One wet bale in the hay mow can set off thousands of dry bales and completely destroy the stored crop, structure (usually mostly old dry wood), and any animals trapped in the floor below. [url]https://en.wikipedia.org/wiki/Spontaneous_combustion[/url]

[QUOTE=chalsall;527730]Decomposition is an exothermic reaction.[/QUOTE]
[QUOTE=kriesel;527839]Given time and other conditions, bacterial action can heat organic material up to the point where inorganic oxidation can take over.[/QUOTE]
But, that is not what sets trash truck alight. If it was you would be seeing the "green waste" trucks burning more than those carrying refuse. The sources that I previously listed are far and away the most common. Decomp heating up is what sets compost and mulch piles on fire. In landfills the temp is not an issue if the oxygen is controlled.

[QUOTE=Uncwilly;527843]But, that is not what sets trash truck alight. If it was you would be seeing the "green waste" trucks burning more than those carrying refuse. The sources that I previously listed are far and away the most common. Decomp heating up is what sets compost and mulch piles on fire. In landfills the temp is not an issue if the oxygen is controlled.[/QUOTE]It's a good reason to leave neither a trash truck nor a farmer's forage box loaded for days or weeks.

Typically a refuse collection vehicle will not have a load in it for more than 20 hours. They might be left (partially) loaded overnight and on a rare occasion over a weekend. If they catch fire it will be at the yard, not on the street. It is standard operating procedure if there is a fire to discharge the load on the street. It is easier for the firefighters to put it out that way. They might run the ram back to try to keep the air out, but that is not generally what is done.

[QUOTE=Uncwilly;527870]<snip>
It is standard operating procedure if there is a fire to discharge the load on the street. It is easier for the firefighters to put it out that way.
<snip>[/QUOTE]
I also wonder what might happen to the [i]truck[/i] if it [i]didn't[/i] discharge a load that had caught fire. I'm thinking, it can't be good.

Thanks for all the answers on combustion.


EDIT: I really came here to lament the loss of a fan on my faithful GTX460: my first GPU. Maybe Alibaba will have replacement fans. :rolleyes: :loco:
I should just lay it to rest. It's had an incredible run from its beginning as a $100 closeout at Microcenter. That acquisition is probably recorded somewhere in GPU computing.

Here in lovely Marin county, CA, after decades of the corrupt utility giant PG&E having diverted $billions/year which should have gone to grid maintenance and tree trimming (and perhaps, modernizations including burying power lines where feasible), things are so bad that PG&E is now preemptively shutting down power to entire counties every time high winds are forecast. Our power's been out since Sat. evening (i.e. for nearly 72 hours), just came back on ~30 mins ago, PG&E only knows for how long, but catching up on stuff. (No WiFi during the interim). Anyhow, got a bunch of stuff to catch up on while the power remains on -- greetings from the 3rd-world nation formerly known as California!

[QUOTE=ewmayer;529235]<snip>
Our power's been out since Sat. evening (i.e. for nearly 72 hours), just came back on ~30 mins ago, PG&E only knows for how long, but catching up on stuff.
<snip>[/QUOTE]
Three [i]days?[/i]

:raman:

So much for the perishables in the fridge. :yucky: :sick:

Hopefully, the power will stay on long enough to re-chill everything, if only to keep down the smell until you can get rid of it.

Perhaps folks could pool their resources of ruined fridge food, and have an "all you can eat buffet," exclusively for PG&E execs.

Hmm, without reliable electric power, you may get to revisit the days before electric refrigerators, and use yours as an "ice box." I'm sure there will be enterprising souls willing to provide ice.

[QUOTE=Dr Sardonicus;529244]Three [I]days?[/I]

:raman:

So much for the perishables in the fridge. :yucky: :sick:
.............
Hmm, without reliable electric power, you may get to revisit the days before electric refrigerators, and use yours as an "ice box." I'm sure there will be enterprising souls willing to provide ice.[/QUOTE]
The days before electric refrigerators, or perhaps electricity itself reached some farm state back country places, included one-cylinder gasoline-engine-driven refrigerators. I saw a long-dead example once, in rural Iowa. I think it may have had a stomp pedal starter, but it's been a long time since I saw it.