Bad day to be a UK TV broadcaster

[ppppenguin]

https://www.bbc.co.uk/news/entertainment-arts-58694894
Too much hanging from a single point of failure. Unlike the Bilsdale TX fire which only(!) took out a limited regional area.

The Register has found an older story from the same field:
https://www.theregister.com/2021/09/27/who_me/

Going back even further, BBC2's opening night was scuppered by a power failure. Didn't matter too much as the number of viewers was probably exceeded by the staff at TC who were trying to find torches and candles.

[Sundog]

Yes some services are to this day still recovering! 
No information about the failure's pathology was available when I looked at the time, but I'm now led to believe that the failure was due to the pressure wave of the suppressant gas causing multiple hard-drive failures. 
Halon gas suppression systems use multiple (up to 100 in my experience) high pressure cylinders that release almost instantly.

This is not a failure mode that many would have envisaged.

[Refugee]

All it takes is one RIFA to set the fire alarm off and the whole lot will get smothered.
What then happens is that the equipment gets written off and dumped without anyone knowing what set the fire alarm off. Nothing will be learned without a simple CCTV camera in the server room to see it before the fire extinguishers cleared the magic smoke away.

[Nick]

Halon was banned by the EU in 2000 and the ban was implemented in the UK in 2003.

There are some special exemption situations, but in my experience halon has been pretty much unknown in most commercial environments for a long time.

Nowadays the trend is towards hypoxic air technology (oxygen depletion) systems that prevent fires starting and spreading in the first place as well as non-ozone-depleting suppression systems such as 3M's Novec.

It's also highly unlikely that an old rifa (or any other) X2 capacitor failure on its own would trigger a full fire suppression response. I have been in data centres in the UK and US with 20,000+ servers in a single space (1,000ft X 300ft space, open cage mainly). These mammoth DCs are failsafe and never bought down by a localised issue. The trick is to contain the problem and deal with it locally.

My experience is mainly in running infrastructure and development for banks and hedge funds in several countries and I haven't seen any halon for 15 years or so

[Raditechman]

I knew someone who worked at Battersea Power station the night of the BBC2 power failure. He used to joke that he switched BBC2 Off.
Last week Radio 4 Today programme had a fire alarm causing interruption to service.
https://www.bbc.co.uk/news/entertainment-arts-59457543

John

[Mark Hennessy]

I think some people use the term "halon" generically - that's my experience, at least. I'm familiar with Inergen systems where I work.

And although I can't go into any detail, we have had a large bunch of hard drive failures caused by the acoustic effects of a release. A similar incident in Sidney some years back was fairly widely reported:

https://www.theregister.com/2014/02/04/l...arm_disks/

As that link mentions, the type of release nozzles makes a difference - and the wrong type were used in our installation (allegedly!).

After our "event", it's definitely something we are aware of across the corporation. But of course, this was Red Bee's building...

[Nick]

I think some people use the term "halon" generically - that's my experience, at least. I'm familiar with Inergen systems where I work.

And although I can't go into any detail, we have had a large bunch of hard drive failures caused by the acoustic effects of a release. A similar incident in Sidney some years back was fairly widely reported:

https://www.theregister.com/2014/02/04/l...arm_disks/

As that link mentions, the type of release nozzles makes a difference - and the wrong type were used in our installation (allegedly!).

After our "event", it's definitely something we are aware of across the corporation. But of course, this was Red Bee's building...

Halon is something very specific and very nasty - it not only is an awful greenhouse gas, it works by rapidly displacing oxygen to extinguish any fire. "Halon" should NOT be used generically (like "Hoover" etc.).

Halon has the unfortunate side-effect of possibly killing or seriously injuring any animal life in the room, including humans. Many years ago (at Smith New Court - a once large City market maker and broker, now owned by Merrill Lynch) I was in their new data centre in Farringdon when some idiot working on the HVAC lit a blow-torch. Normally, if humans are in the room the Halon should have been disabled, but it wasn't. The alarm went off (30-seconds warning) and you've never seen a large room (size of three tennis courts) fully of very expensive equipment clear of people so quickly. The alarm was cancelled but the risk of either suffocation or serious physical injury due to the heavy floor tiles flying around is enormous.

Inergen does not kill people in the room and is kinder to the environment (has some CO2 in it) - it's normally vented from the ceiling rather than ceiling AND underfloor (underfloor is risky as the floor tiles can get thrown around and they are seriously damaging to anything that intersects with their flight path). It's a pretty explosive discharge - basically a series of huge red cylinders containing highly pressurised gas that have big solenoid valves on top that just open really fast and vent down a bunch of 1" to 2" pipes. An impressive sight. You have to have special automatic damper vents that open as the gas is discharged to relieve the pressure, else, to quote Michael Caine, you'll "blow the bloody doors off".

As I previously mentioned, the current trend is just to keep the level of oxygen in the room low enough to prevent fires establishing but high enough to keep people alive. Just stop the problem at source.

[ppppenguin]

Agreed that Halon is nasty. Although it displaces oxygen I thought its primary action was to muck up (technical term, can't be more specific) the chemistry of combustion thus extinguishing the fire. In ancient times carbon tetrachloride was used in some extinguishers and worked this way. The by products of fire and just about any chlorinated hydocarbon include phosgene. Lovely

PS: I looked up Inergen and it works simply by displacing oxygen. This page has a couple of howlers: https://www.firesuppression.co.uk/inergen.aspx
"INERGEN fire suppression systems also have a zero global warming potential,....". It contains CO2.
"..as it is organic in structure ...". It's Argon, Nitrogen and CO2. At a stretch I suppose you can call CO2 organic but it's not usually thought of as such.

While not toxic, it can still kill by suffocation.

[Nick]

Agreed that Halon is nasty. Although it displaces oxygen I thought its primary action was to muck up (technical term, can't be more specific) the chemistry of combustion thus extinguishing the fire. In ancient times carbon tetrachloride was used in some extinguishers and worked this way. The by products of fire and just about any chlorinated hydocarbon include phosgene. Lovely

PS: I looked up Inergen and it works simply by displacing oxygen. This page has a couple of howlers: https://www.firesuppression.co.uk/inergen.aspx
"INERGEN fire suppression systems also have a zero global warming potential,....". It contains CO2.
"..as it is organic in structure ...". It's Argon, Nitrogen and CO2. At a stretch I suppose you can call CO2 organic but it's not usually thought of as such.

While not toxic, it can still kill by suffocation.

Quoting from the Inergen brochure at https://www.nist.gov/system/files/docume...301006.pdf : (always go for the source, Luke!)

INERGEN works by displacing a proportion of the air within the enclosure, thereby lowering the oxygen to a level that cannot sustain combustion and at the same time ensures the  oxygen remains at levels within the enclosure that are safe for humans.

...so it doesn't kill humans. Not if the installation is designed correctly.

[Mark Hennessy]

Please, let's not get hung up on the chemistry, as it's pretty OT for this forum.

Let's also not get too worked up about the fact that some people use the term "halon" generically to refer to fire suppressant systems. Everyone I've heard do that was very much aware that halon is long-obsolete, and they were knowingly (and explicitly: e.g. "halon-like") being generic - and that's because (a) everyone has heard of halon and knows what it is and how it works, and (b) there are several options today, but not everyone has heard of them all. And I'm not sure it's a good look to our new joiner, who - as I gently hinted earlier - was almost certainly using the term generically.

The real point here is the acoustic shock-wave causing head-crashes on the mechanical hard drives. I still remember how amazed I was when I first encountered it, and with my audio engineering hat on, I think it's impressive

And the crucial learning outcome from such incidents is making sure you specify the correct outlet nozzles to minimise the risk of this. When specifying a fire-suppressant system, you can usually leave it to the contractor to worry about which specific gas to use; but if you don't tell them otherwise, they'll - quite understandably - fit the cheapest nozzles they can find. Therefore, we no longer leave that choice to them, and whoever manages the Red Bee building will no-doubt be arranging to have the nozzles swapped out at the earliest opportunity