Fire Extinguisher for the workshop?

[HopperParticipant @hopper]

Case in point: I was just out in the workshop this morning tack welding the legs on my ongoing Stirling engine fan project when I felt my own leg getting vaguely warm. I thought it a bit odd as I was only tacking, not running long welds. Then I smelt a hot burning smell so flipped the mask up for a look around.

A discarded rag on the floor was well ablaze. No doubt it was good and oily. Flames over a foot high already. Now, fortunately I do all my welding on the concrete driveway outside my shed, for this exact reason. And I was wearing my work boots for welding. So I was able to stamp it out with no major dramas. Then pick up the rag and douse it under the nearby garden water tap.

But only four feet away on the other side of the tin shed roller door was my leaky old 1942 Harley, which I had running earlier in the day and had noticed a slight petrol smell after I forgot to shut the fuel petcock after running the bike. The old carby tends to weep a bit sometimes if the needle does not seal fully on the float.

And of course surrounding the bike is all the usual workshop detritus of oily rags, drip tray under the bike containing leaked oil, almost empty jerry cans of petrol, half-used 5-litre plastic bottles of engine oil and hydraulic oil and an old refrigerator full of tins of paint, thinners, spray cans etc. And a couple of other old bikes with half full petrol tanks and carburettors not known for their leakproofness (Amal, I am talking about you).

It could have been a disaster. Or I could have grabbed the large full-sized fire extinguisher I keep by the door and averted it if need be – maybe.

It just goes to show, yes a fire extinguisher or two are essential in the workshop.

But so is taking sensible precautions like not leaving oily rags lying around on the floor. And keep your workshop rubbish bin outside the workshop because it usually ends up full of oily rags, paper, empty spray cans etc etc that are the perfect firestorm.

And do your welding/silver soldering and grinding outside – weather permitting – but make sure you clear the old rags away first and move the outdoor rubbish bin away.

[Bo’sunParticipant @bosun58570]

Morning All,

Picking up on a couple of points from old mart & Hopper.

I’m guessing that not all foam extinguishers are dielectric and suitable for electrical fires, because various FE suppliers still say no.

As I understand it, rags soiled with solvents & oils can self combust if left in a bin.  I always dispose of mine in the outside dustbin.  Maybe still a risk, but at least it’s not in the workshop.

[Bo’sun]

On Bo’sun Said:

….
As I understand it, rags soiled with solvents & oils can self combust if left in a bin.  I always dispose of mine in the outside dustbin.  Maybe still a risk, but at least it’s not in the workshop.

I hadn’t heard that one before. My workshop bin being  black plastic and left outside in the tropical sun is probably a prime candidate! I might have to move it a bit further from the workshop again.

[Hopper]

On Hopper Said:

On Bo’sun Said:

….
As I understand it, rags soiled with solvents & oils can self combust if left in a bin.  I always dispose of mine in the outside dustbin.  Maybe still a risk, but at least it’s not in the workshop.

I hadn’t heard that one before. My workshop bin being  black plastic and left outside in the tropical sun is probably a prime candidate! I might have to move it a bit further from the workshop again.

The issue is that the Drying Oils used in Oil Paint and some Varnishes ‘dry’ by absorbing Oxygen during which process they heat up.  The heat is dissipated safely when the paint is drying on a surface, but it can build to ignition point when soaked into a bundled up rag, that’s kept well insulated by dropping it into a dustbin full of other cosy rags.

Many, many incidents over the years because paint jobs often generate a lot of oily rags and other inflammables that end up festering in in a bin, plus the waste bin is likely to be near unused oil-paint and solvents that go up after the fire starts.    The culprit most often mentioned in fire reports is Linseed Oil, as in this 1991 Philadelphia example.   Linseed Oil is also used to improve woodwork.

I get rid of rags contaminated with Linseed Oil by soaking them in water and putting them unfolded and generously wet into their individual plastic bag.    Probably overkill, though it gives me peace of mind!  Although spontaneous combustion is real, it’s pretty rare, with many a busy workshop carelessly disposing of tons of Linseed Oil soaked rags over several decades without incident.  And then some poor soul has their house burnt down after polishing a cricket bat once.  Gremlins have a weird sense of humour!

Dave

 

[bernard towersParticipant @bernardtowers37738]

surely it must be a lot less trouble to walk in the garden with a box of swan vestas!!!

[Robert Atkinson 2Participant @robertatkinson2]

Cooking oil on rags can also self combust. More than one curry house has burnt down from linens waiting to be laundered.
As Dave says if you try to demonstrate it it won’t work but when you don’t want it to happen it will.
Putting any oxidiser near a potential fuel is a bad idea.

Robert.

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