Sprinklers

[JohnP]

A school has just gone up in flames in my area. Usual photos of it burning inside whilst water is put on the outside. Usual cries for sprinklers - but these can be vandalised and could cause problems.

I know about dry risers - usually to Landing Hose Unions - but what about a simple array of pipes in the roof space with open nozzles. In the event of a fire then the Fire Engine hooks up and dowses the fire from the inside using the fixed nozzles - no need to enter the building. Notre Dame would have possibly been saved if such a simple system was in place.

Any thoughts? It seems a compromise to a full sprinkler system but has the advantage of not being automatic and able to flood the building.

[nightjar]

Unlike a sprinkler system, which releases water only in the vicinity of the fire, that would release water throughout the building. Fine if the whole building is on fire, but it could result in unnecessary water damage if the fire were only localised.

There are dry sprinkler systems. They contain compressed air or nitrogen, but they still need a detector head to activate. That releases the gas which, in turn, activates a valve that allows water to enter the system.

[Jim GM4 DHJ ...]

A type of automatic dry riser you mean?...

[JohnP]

"Jim GM4 DHJ ..." [e-mail] wrote in news:zvieH.13617$ [e-mail]:

As I understand it a dry riser usually just feeds hose points on upper floors so they need firement to enter the building and use a safe stairwell.

[JohnP]

nightjar [e-mail]> wrote in news:EsudnUwOvq [e-mail]:

Good point - Perhaps with Zones - selected by the fire brigade.

[Chris Hogg]

IIRC large electrical installations such as large switch rooms in basements etc have CO2 cylinders installed and ready to be discharged in case of fire, thereby depriving the fire of oxygen but not electrocuting anyone by throwing water around. But there's the danger of suffocation if the system goes off and there's someone trapped nearby.

[GB]

I had an MRI scan recently, and the room had a very, very heavy steel door that appeared air tight. I assume that was to protect the rest of the building if the helium boiled?

[Peter Parry]

Sprinkler heads which are recessed so flush with the ceiling are commonly used if there is a problem with idiots smashing the more common head. when triggered by localised heat the head extends and emits a water spray. The head sometimes uses a heat initiated wax motor so no power supply needed.

Being automatic is a considerable advantage, with sprinklers the fire is usually out or well contained before the fire service arrives. Flooding a building is generally a really bad idea, the water damage is often more expensive than the fire damage.

[jon]

I don't think there is anything worse than squeaky voices, especially with weather forecasters.

[Robin]

<snip>

If this was the door through which you entered it may have been just to maintain RF shielding. They don't plan on the patient being left to suffer if quenching leads to increased pressure in the scan room, or for any window to the control room to blow out explosively.

[AJH]

Presumably if the wax stopcock is remote from the sprinkler head it can switch off once the temperature drops and so minimise damage?

[Andrew]

I was an IT contractor at an insurabnce co in Croydon where the door to the computer room on the top floor had two push buttons, one to ring the bell to request entrance, and the other to set off the Halon fire extinguishers. This was actually activated twice during a 4 year period by people who thought it was the door entrance button, despite being protected by a sliding perspex cover and clearly marked.

[Andrew]

"Accompanying nurse from the wards attempted to bring an unchecked oxygen cylinder into the magnet room despite being briefed beforehand in relation to safety around the MRI and specifically the oxygen cylinder. After being stopped by radiographers from taking cylinder any closer to the machine and potentially causing serious harm to both patient and equipment the nurse was unapologetic and did not seem to understand the gravity of the situation despite all the prior warnings." :-

[GB]

Some M&S pants have a little tiny metal badge attached. Mine did, on the day I had a pelvic MRI scan. The radiologist didn't notice it, and I forgot about it. It's some sort of alloy and probably weighs a gram.

It didn't ping into the magnet, so probably non-ferrous. It didn't heat up from the RF radiation. But, it did cast a shadow on the scans. Fortunately, the radiologist had some scissors handy, and it only took an extra 15 minutes to redo the scans.

[T i m]

And the 2000 pigs that recently burned to death , trapped in their tiny pens. ;-(

I can't understand why they didn't have such a thing in the pig farm, after all, there is hardly anything that was likely to be more damaged by water than fire (including the pigs).

Or a fail-safe exit system that gave the poor things a chance to escape such a death (not that they had much of a life, burning to death can't be a nice way to go).

Cheers, T i m

[JohnP]

The wax motor seems a better idea than the glass vials.

[Andrew]

Circumcision or castration ?. :-)

[GB]

I was worried at the time, but it was just a badge-ectomy. :)

[newshound]

Expensive! For every foolproof system.....

[newshound]

It's a bit like the Grenfell argument. You need to do a cost benefit analysis including the cost of false actuation. Apart from paper and desks, schools are mostly not particularly flammable. OK they contain computers these days, but even computers are cheap.

Sprinklers make sense in department stores and many types of factory because the contents are high value, and they prevent spread.

High pressure "misting" systems are used around rotating plant in power stations where there are large lubricating oil tanks. Power stations typically have dry risers too.