Tumble Dryer Fires … Irish article citing spontaneous combustion blames short / cold wash cycles.

[novum]

I just spotted this article in the Irish Independent, quoting an insurance company talking about risks of tumble dryer fires.

They’re claiming that clothes have spontaneously combusted several hours after being dried due to the presence of flammable oils that aren’t being adequately removed in short wash cycles, as people are trying to save energy and that people are skipping the cool down cycle. Seems more about people just pulling clothes out too soon, to avoid waiting rather than energy.

Surely the same oils would be present from fabric softeners etc, but also how hot can a dryer possibly be? If it’s causing clothes to ignite?!

I’m just not quite sure about the facts in this.

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www.independent.ie

 

[combo52]

Vegetable basted cooking oils in clothing

Usually do not wash out completely, and as they start to break down, they create heat and can spontaneously combust. There are many cases or even a basket of clean dry laundry sitting in a laundry room will spontaneously combust. It doesn’t even have to be in the dryer.

It’s probably more likely to happen in the dryer with the added heat toward the end of the drying cycle when the moisture is mostly or completely gone however and then the dryer gets blamed.

John

 

[me]

As far as I know it is only certain types of oil that spontaneously combust due to them oxidising which can generate enough heat to reach their combustion point if they are scrunched up. My father was a keen woodworker and woodturner, and used a lot of Danish oil (a blend of oils including tung oil, I think some contain a catalyst as well) and the cloths used to apply it had to be stored in air tight tins and carefully disposed of to prevent them self combusting.

There's a list of some of these oils here:- https://www.firehouse.com/rescue/article/10528863/the-phenomenon-of-spontaneous-combustion

I guess if a fire starts in a tumble dryer it might in some cases only smoulder if it gets starved of oxygen and flare up when the door is opened, giving the appearance of spontaneous combustion.

There probably are quite a few of the 3.8 million tumble dryers recalled by hotpoint-indesit due to fire risk, still in use without the required modifications. Those would get lint trapped in the seal at the back of the drum and bits could drop out onto the element, ignite and get blown into the drum, or set the seal and the lint stuck to it alight.

I have one of the recalled vented models, that also had a problem with lint escaping through the drum seal and filling the case, from where it could get blown through the element and back into the drum. I think it was caused by the rear drum olite bush wearing out causing the drum to tilt down at the back, which opened up gaps in the drum seals.

 

[novum]

The only dryers here that I always found really WAY too hot are the traditional air-to-air condenser type.

A lot of them were quite ineffective and ran way too hot and you'd also find a lot of people never or very rarely cleaned the condensing unit. You were supposed to remove the whole heat exchanger and wash it out with a shower once in a while, but the reality is a lot of people probably only do that if it blocks.

I don't think most of these issues apply to the most sold type of dryers these days, which are all heat pump based.

 

[henene4]

Many dryers have warnings that any clothing once soiled with oil should not be dried.

Any oil on clothing is way easier to ignite - it's like a wick on a candle.
If you combine that with the heat of a dryer, you can get runaway oxidation reactions easily.
And the more oil remains, the more likely that is.
And the colder and shorter you wash, with less and poor detergent (see those "make your own detergent" trends), the worse it gets.

The article also mentions people skipping the cooldown cycle - and if you just plonk hot clothing in a basket with no airflow that can very much cause heat to build up.

 

[novum]

Most of the more recent dryers are heat pump based and don’t really seem to heat clothes up very much at all.

The scariest ones I’ve seen have been old style condenser dryers that aren’t maintained. I encountered one in a rented apartment that was so clogged up it basically had no airflow. The heat exchanger looked like it had never been rinsed out, and they were operating it with the cover removed, so it was just blowing air into the room - it was in an outhouse so they didn’t care.

I’ve also seen vented dryers that had crazy amounts of lint the ducts and filters.

In general, I find some of those articles tend do take the extreme cases. The biggest issues seem to be lack of very basic maintenance.