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The Bellinghman
Date: 2011-08-11 20:10
Subject: Sorry
Security: Public
I appears that I need to apologise to the north half of Royston tonight.

It started a little before 16:00. I was working away at some code that is meant to generate PDF files, trying to persuade an underlying component of the virtues of CMYK, when beyond my monitor, I saw something flying up into the air, trailing coloured smoke. Since this is an industrial estate, on the north edge of a small town, my brain contradicted my immediate first reaction, which was that someone had just fired a smoke grenade.

Yes, I know there have been rioters in some parts of England, but for Royston, mid afternoon, to be the first place that British police started deploying such countermeasures? No way. It must have been an odd reflection on the inside of the window.

But I looked again, and could see a yellowy-brown smudge drifting leftwards behind the Hotel Chocolat offices.

OK, something really there, and it was just our side of a building that is on the main road of which our office's side road is.

Well, someone had had a mishap.

Presumably whichever company it was would sort it out pretty sharpish. I was fairly sure it was a company that did printed circuit boards.

And so for five or ten minutes, we watched from a distance, and our disquiet mounted, since there was now quite a strong plume of ochre smoke coming from behind that hedge. After a bit, I wandered out through our car park, across the car park beyond (the one shared by us, Hotel Chocolat and the sorting office as an overflow), and got close up to the fence. From there, I could see into the back yard of the company in question. There didn't seem to be anyone around.

Not too good.

There was a large tank - about a metre high, a metre in diameter - which had a now-open opening on its top, maybe 20 cm across. Out of that opening was coming a solid pillar of the fumes which dissipated pretty quickly in the air.

I then went back to our reception, and we used Google Maps to zoom in to find the name of the company in question - Tru-lon Printed Circuits. Our receptionist Yelsel called their number, which was answered fairly quickly. Somewhat to our surprise, it turned out to be someone in Stevenage, which is a different town halfway down the county from us. It looks like the reason that nobody at Tru-lon was doing anything was that there was nobody there - the premises had been closed a while back. The person in Stevenage guessed from our description that the fumes were nitric acid, and said they'd send a chemist up to deal with it.

All well and good, but about 20 minutes after the initial pop, it was still smoking, even if nothing like as badly as it had been:

The smoking tank

So, we called the Fire Brigade.

About half an hour later, they were taking it quite seriously. We had a visitor telling us to stay indoors. At lkeast, that's what we think he said — it can be a tad difficult to understand someone speaking through a respirator:

New company dress code


And then, just before 18:00, the police arrived in force to evacuate us.

The road blocked off

That's an impressive array of vehicles there.

It appears that both roads into the industrial estate were closed off, and that even the route into town from the A505 was closed off.

So, this is my apology. If we'd not done anything, that tank would probably have continued fuming at a low level, without anyone being put out, until it finally evaporated. Instead, there was near gridlock in town. I can only think they react this strongly because they're prepared for problems at Johnson Matthey
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Kari Sperring
User: la_marquise_de_
Date: 2011-08-11 19:26 (UTC)
Subject: (no subject)
I guess they were also worried that there might be other chemicals nearby that might also burn. I'm underwhelmed by the owners, who left that lying around unmonitored.
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Alex McLintock
User: alexmc
Date: 2011-08-11 19:40 (UTC)
Subject: (no subject)
Well, I don't know. It looked like there was a very visible signal as soon as a problem started - a plume of coloured smoke soon attracted attention

;-)
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The Bellinghman
User: bellinghman
Date: 2011-08-11 23:44 (UTC)
Subject: (no subject)
During daylight working hours, yes ...

"By day a pillar of smoke, by night a pillar of fire ..."
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The Bellinghman
User: bellinghman
Date: 2011-08-11 20:36 (UTC)
Subject: (no subject)
Indeed so. The premises in question are actually boarded up, hence the lack of quick response. On the other hand, if it had happened when we didn't have people looking in that direction, who knows what could have happened.
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dorispossum
User: dorispossum
Date: 2011-08-11 19:30 (UTC)
Subject: (no subject)
You (or rather the chemical event) were on local news. Hope it's all over now, and you're all fine.
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The Bellinghman
User: bellinghman
Date: 2011-08-11 20:32 (UTC)
Subject: (no subject)
Oh, we're fine. The majority of whatever got vented came out in the first few minutes, and by the time the cleanup happened, there was pretty much nothing left to worry about.

But yes, they did need to check it in case.
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Muninn and Huginn
User: muninnhuginn
Date: 2011-08-11 21:45 (UTC)
Subject: (no subject)
Ooh! I guess that rather trumps our watching the fire engines arrive to deal with this as we left the house this morning.
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The Bellinghman
User: bellinghman
Date: 2011-08-11 23:22 (UTC)
Subject: (no subject)
Well, I think we had at least four engines, and probably about a dozen squad cars. Though on any other day, I'd have given your fire a few points.

Edited at 2011-08-11 11:24 pm (UTC)
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Simon Bradshaw: WTF Adama
User: major_clanger
Date: 2011-08-11 21:50 (UTC)
Subject: (no subject)
Keyword:WTF Adama
You were near a leak of RED FUMING NITRIC ACID?

That stuff's the 'toxic' bit in 'toxic hypergolic rocket propellants'. Running away upwind is very, very prudent.
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The Bellinghman
User: bellinghman
Date: 2011-08-11 23:21 (UTC)
Subject: (no subject)
I'm not sure it was all the way to red fuming - the fumes were more yellow.

But looking at the page, hmmm, 30% is quite strong enough, thank you.
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The Bellinghman
User: bellinghman
Date: 2011-08-12 08:42 (UTC)
Subject: (no subject)
Not having checked the MSDS myself, I'll take your word for it. But it will have been nasty stuff.

And yes, I think your degradation in a sealed container was exactly what had been going on, and a nice warm afternoon finally got it to the point that the cap couldn't hold the pressure any more.
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Sion: home page portrait
User: sion_a
Date: 2011-08-12 10:13 (UTC)
Subject: (no subject)
Keyword:home page portrait
White fuming nitric does indeed build up a nice head of NOx when heated in a sealed (plastic) container, and gives off the resulting red/yellow cloud when pressure is released. I know, because my first summer job involved heating fuming nitric acid in PTFE pressure containers. NOx is deeply unpleasant, and fuming nitric is the scariest thing I handled in my wet chemistry days (beating out liquid nitrogen). I think the fire-brigade's response was entirely proportionate.
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Jos Dingjan
User: happydisciple
Date: 2011-08-12 12:40 (UTC)
Subject: (no subject)
Liquid nitrogen is fiiine, as long as you're a bit sensible. Worked with it (and liquid helium) when I was a student.

My research group colleagues at the time told me about their experience working with liquid hydrogen, in glass dewars. Windows open, just in case a dewar would go pop. Oh, and somebody outside their window with a blowtorch. They asked them to stop doing that.

Scariest I've worked with is HF, never again if at all possible.
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HairyEars
User: hairyears
Date: 2011-08-12 17:31 (UTC)
Subject: A dark and stormy Nitre

No, I think it was White Fuming Nitric Acid - WFNA. As delivered, this has no added nitrogen tetroxide (unlike Red Fuming Nitric Acid) and a maximum specified concentration of dissolved nitrogen oxides of 0.5%

It degrades over time, and the proportion of dissolved oxides goes up: you'll see light-brown fumes of NO2 at the surface - but not the cedar-wood reddish-brown fumes of Nitrogen tetroxide mixed with the dioxide. That's RFNA, not WFNA! That or very old, and very badly-stored old acid.

Needless to say, allowing NO2 fumes to build up is extremely dangerous - far more so than venting these toxic gases to the atmosphere! (Or through a filter, which is what you're actually supposed to do when storing it in bulk).

Among other issues, the pressure in an unvented container allows much more gas to dissolve; when the safety-valve eventually pops, the whole lot fizzes out of solution at once, creating a fog of Nitrogen dioxide gas and aerosolised Nitric Acid.

This is the yellowish smoke that you saw.

This smoke is scalding hot as well as toxic and corrosive: Nitric Acid reacts vigorously with water and the aerosol will heat up, even from the half-percent or so of water in the air.

The fire brigade had reason to be cautious: water could've caused a violent explosion, scattering corrosive liquids capable of starting fires. The source of the acid - the container - will have been dealt with by pumping-out into a safe receptacle and *maybe* neutralising the contents, very carefully and very slowly.

As for the affected area: eventually they'll have satisfied themselves that the gases have diffused to a degree that mitigates this danger, and sprinkled (not hosed!) the contaminated zone with water.

The company responsible (or irresponsible) are liable for cleanup costs, but the fines are surprisingly small - the vast majority of industrial accidents and pollution incidents, even ones that we would think of as serious, go to the magistrates and no further.


Edited at 2011-08-12 05:46 pm (UTC)
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The Bellinghman
User: bellinghman
Date: 2011-08-12 20:02 (UTC)
Subject: Re: A dark and stormy Nitre
I think you're probably right. Except there's a possibility that this might not have been terribly clean Nitric anyway since the company that had been there was a PCB company, and it's possible that this was used rather than fresh. If so, there will have been interesting copper salts in there too.
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Linz
User: k425
Date: 2011-08-12 11:27 (UTC)
Subject: (no subject)
it can be a tad difficult to understand someone speaking through a respirator

They need Darth Vader to translate.
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lewis_p_bear
User: lewis_p_bear
Date: 2011-08-12 20:55 (UTC)
Subject: Boom
You might like to look at the opposite view: I.e. if not stopped the dam thing might have gone BOOM and that would have upset considerably more people. Anyone who find it annoying to be on fire, for example.

We say Good on you!!!.
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The Bellinghman
User: bellinghman
Date: 2011-08-13 10:56 (UTC)
Subject: Re: Boom
Indeed so ... my apology was mostly tongue in cheek.
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