Electronic Fire Extinguisher...Smart or Stupid? - Page 1
Forum section: electronics / general

author: Cyberdragon
author_rank: Super Contributor
timestamp: October 30, 2017, 07:48:30 pm
content: https://plumis.com/automist.htmlI have to say, it's not piss ant like I thought it would be, but I still think it's needlessly overcomplicated, with potential for failure in an emergency.

author: Halcyon
author_rank: Unknown
timestamp: October 31, 2017, 04:35:09 am
content: Great in very specialist applications but pointless for almost everything else.There is a reason why fire suppression systems are as simple as possible involving little to no electronic logic. In the case of a complete failure of a building's electrical system, fire suppression should still be at least partially functional.Clive Mitchell actually did a very good explanatory video yesterday on how sprinkler heads work.Larger buildings and towers will generally have an auxiliary pump which will kick in if one or more sprinkler heads are triggered -- the circuit will sense a drop in water pressure and start a diesel pump to boost water pressure, further water pressure can be added by connecting the building directly to a fire truck (you'll see "booster valves" and inlets on many buildings). The water pipe is also connected to a bell on the outside of the building so that the all that is needed is water flow to make the alarm bell sound.Electronic systems will "fail over" to a fault condition if it's unable to protect any part or all of the building or detects an anomaly (other than fire or smoke). A fault alarm still sends a signal back to the Fire Brigade and will dispatch fire trucks to check the building and the system. The only time a fire system won't report "back to base" is if someone forces the system or particular zones into "isolate" mode.

author: tooki
author_rank: Super Contributor
timestamp: October 31, 2017, 06:17:45 am
content: Quote from: Cyberdragon on October 30, 2017, 07:48:30 pmConsider editing the thread title: you mean sprinklers. Despite the fact that sprinklers and other fire suppression systems can extinguish fires, the term "fire extinguisher" means specifically and exclusively the handheld metal cylinders (the giant aerosol cans, basically).As for this thing, I'm baffled as to what problem it solves. It adds tons of complexity, with the added points of failure this brings, and I can't see what advantage it has. They praise the low water flow, but given that most sprinklers will use zero water throughout their entire lives, what's this accomplishing?? And surely the cost of this electronic gizmo is higher than that of a few extra feet of pipe and another sprinkler head.

author: glarsson
author_rank: Frequent Contributor
timestamp: October 31, 2017, 07:08:26 am
content: If it can perform the same function with a much lower water consumption then that is a huge advantage as it reduces the risk of water damage to the building.

author: Halcyon
author_rank: Unknown
timestamp: October 31, 2017, 08:19:21 am
content: Quote from: glarsson on October 31, 2017, 07:08:26 amUntil the fire brigade turn up with their really long, leaky hoses. Some of their hoses are actually designed to weep water along their length to prevent burning material from making holes in the canvas/rubber when they are dragged through burning buildings or through burning scrub fires. Not to mention the larger diameter hoses at full pressure can empty a fire truck in less than a minute... that's a lot of water!

author: G7PSK
author_rank: Super Contributor
timestamp: October 31, 2017, 08:57:19 am
content: It's not just the amount of water from a fire truck, it is also the pressure that causes damage, I have seen fire hoses not only knock plaster off walls but also knock block wall over. Watching a fire crew go to work is like watching legalized vandalism.

author: innkeeper
author_rank: Unknown
timestamp: October 31, 2017, 09:01:48 am
content: maybe i miss understood the demo but... looks like there it will put out grease fires?

author: timb
author_rank: Super Contributor
timestamp: October 31, 2017, 12:12:30 pm
content: Quote from: innkeeper on October 31, 2017, 09:01:48 amYes. These don’t appear to work like standard ceiling sprinklers, which spray droplets of water.On the other hand, these generate a fine mist, which would get caught in the updraft from the fire, preventing it from settling in the pan like larger water droplets would.

author: sokoloff
author_rank: Super Contributor
timestamp: October 31, 2017, 12:37:48 pm
content: Quote from: timb on October 31, 2017, 12:12:30 pmIsn't that almost exactly what you want though for a grease fire? You don't want to get liquid water down into the >100°C grease as that just boils, spatters, and spreads the fuel around more, exposing more of the fuel to oxygen and tending to flare up the fire. Small droplets of water (provided you have enough mass flow rate of them) will tend to evaporate, consuming the  latent heat of vaporization from the updraft, cooling it, and helping to break the updraft.

author: m98
author_rank: Frequent Contributor
timestamp: October 31, 2017, 01:54:41 pm
content: Looks like a great invention to extinguish most kinds of fires that occur in homes and offices. Regular ceiling sprinklers react much slower and do create a lot of damage in case of their activation.I think Halcyon missed the point, this product is designed so a fire can't even reach the point where firefighters need to extinguish it, which isn't possible with passive mechanical systems. A ceiling sprinkler reacts when you're already dead and the room is in flames. That's too late, regardless whether it extinguishes the remains reliably or not.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: October 31, 2017, 04:12:58 pm
content: I remember hearing about water mists many years ago, I think it also cools the fire as well as preventing stuff from combusting. I vaguely remember a guy with a high pressure cylinder on his back blasting the spray into a lit room and the fire going out very quickly. Ah yes, the mist evaporates quickly and draws out heat quicker than normal water drops, and also takes away the oxygen from the fire.http://fire.nist.gov/bfrlpubs/fire00/PDF/f00180.pdfAnother good idea awaiting development,Ken

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: October 31, 2017, 06:56:30 pm
content: While sprinklers are very effective at fire suppression they are also incredibly destructive if they go off unintentionally. Particularly in domestic buildings with non water resistant materials like drywall and chipboard.It also has to be remembered that water getting into switchgear canstarta fire. That happened at an airfield about 100 miles from here. They lost three aircraft and had several more damaged in the ensuing blaze, caused by a leak in the hangar roof dripping onto the switchgear.If this idea provides a controlled stream that is shut off once the fire is out, then it is potentially better.Anyway, call that fire extinguisher? Huh.Thisis a fire extinguisher!

author: Cerebus
author_rank: Super Contributor
timestamp: October 31, 2017, 11:38:34 pm
content: Quote from: tooki on October 31, 2017, 06:17:45 amIn places where there is a sensible fire code the cost of a sprinkler system is much more than that. When the Grenfell fire was the subject of discussion on here I did a little bit of research and the UK fire code for sprinkler systems calls for huge header tanks, or basement tanks with self contained, self powered pumping systems. Even a small domestic system would run to £10,000 or more, for a commercial building or high rise, start at £100,000 and work up.

author: timb
author_rank: Super Contributor
timestamp: November 01, 2017, 12:09:00 am
content: Quote from: sokoloff on October 31, 2017, 12:37:48 pmYes, that’s exactly what I was trying to say. I had more to my post but must have accidentally deleted it or something. No matter, you did a good job of summarizing what I was trying to say.

author: Cyberdragon
author_rank: Super Contributor
timestamp: November 01, 2017, 12:11:58 am
content: But there inlies the question. Does this thing actually meet fire codes, or is this purely a special case device?

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 01, 2017, 12:24:14 am
content: Quote from: Cyberdragon on November 01, 2017, 12:11:58 amIt looks to be a device that's nice to have if it works, with nothing lost if it fails. That would be a definite no on the fire code.

author: hermit
author_rank: Frequent Contributor
timestamp: November 01, 2017, 02:29:31 am
content: Can I exempt my fireplace?

author: Mr. Scram
author_rank: Super Contributor
timestamp: November 01, 2017, 02:32:26 am
content: Quote from: hermit on November 01, 2017, 02:29:31 amMostly yes.

author: BradC
author_rank: Super Contributor
timestamp: November 01, 2017, 03:11:58 am
content: Quote from: Kilo Tango on October 31, 2017, 04:12:58 pmWe looked at mist suppression many years ago, and it does all you say. It's also a boon for areas with electronics (like IT closets or rooms with a large array of active equipment that does not have gas suppression) as it really does minimise damage. Of all the water based systems it's certainly the lesser evil.Quote from: Kilo Tango on October 31, 2017, 04:12:58 pmNot really, it has been developed to death and there are many companies offering variants. This is just a domesticated version with a bit more complexity to offset it not being part of an integrated solution.The problem is it's maintenance intensive. The mist nozzles are necessarily tiny and are prone to clogging, the pressures required are higher than your average wet or dry head sprinkler, so more infrastructure required and you need some form of reliable trigger system. Nothing offered to date is as reliable as the old wet head sprinkler.On the other hand, as already mentioned it's effective for a number of fire types that sprinklers are not, minimises damage to the building and its contents and is super effective at suppressing the fire. Minerals in the water can be an issue, as is routine testing/maintenance.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 01, 2017, 03:18:13 am
content: What about have the "smart" sprinkler be the first stage with an ordinary "dumb" sprinkler as the backup?

author: BradC
author_rank: Super Contributor
timestamp: November 01, 2017, 03:52:43 am
content: Quote from: NiHaoMike on November 01, 2017, 03:18:13 amYep. The issue there is your detection for the first stage needs to be significantly more sensitive than the thermal bulb on the sprinkler. So something like VESDA. I can't see how you'd get a thermal or rising rate thermal to discriminate early enough to prevent the conventional sprinkler going off.A bit like putting a 20A circuit breaker upstream of a 16A and expecting the 16A to trip first. It might, but then it might not.

author: Halcyon
author_rank: Unknown
timestamp: November 01, 2017, 05:52:51 am
content: Quote from: m98 on October 31, 2017, 01:54:41 pmNot missing the point at all. I said in my first post that the product isgreat in very specialist applications but pointless for almost everything else.These products are specifically marketed as cost effectivehomefire sprinkler alternative with innovative watermist technology. Almost everything points at the domestic market in areas where fire fighters WILL be able to reach.As for being already dead when a typical sprinkler activates, nothing can be further from the truth. A typical sprinkler head will activate within seconds of the ceiling temperature reaching 68°C. That aside, inhabited rooms don't just "burst" into flames, fires spread gradually.If you were to install sprinkler systems in a domestic home, the bedroom is probably the only place I'd consider putting one, but I'd much sooner just install a combination ionisation and photoelectric smoke alarm.

author: CJay
author_rank: Super Contributor
timestamp: November 01, 2017, 07:18:59 am
content: Quote from: BradC on November 01, 2017, 03:11:58 amI've worked in a few data centres with reduced oxygen environments, it's just not possible to start a fire in them but even then they're backed up by halon or whatever the current legal equivalent is.Not sure I'd want a water mist system anywhere near my datacentre if there was a chance it was still running.

author: Halcyon
author_rank: Unknown
timestamp: November 01, 2017, 07:27:09 am
content: Quote from: CJay on November 01, 2017, 07:18:59 amIn any serious server room or data centre, you don't want water anywhere near it. The mist will likely cause more issues than a localised sprinkler head. A room-filling mist of water vapour will be dragged into every bit of equipment through the air flow in those kinds of environments. Instead of maybe having a few racks taken offline, you're now looking at an entire room where equipment will need to be powered off for safety, dried and inspected before returning it back into operation. Spinning magnetic hard disks and tape drives/cartridges really don't like moisture.Anyone who is serious about fire suppression in electrical and server racks/rooms will be using gas, even if it's just plain old CO2.

author: BradC
author_rank: Super Contributor
timestamp: November 01, 2017, 07:47:46 am
content: Quote from: Halcyon on November 01, 2017, 07:27:09 amAnd therein lies the problem. There are a *lot* of organisations with "serious" data centres that are engineered and run by muppets.Heck, I've seen rows of racks with "Rain hats" on them to protect against leakage from the wet pipe system, let alone an unintentional discharge.Nothing like a contractor bumping a head, ruining $6M worth of equipment and causing an "impaired functionality" incident at a major international airport to ruin your day, especially when not 12 months earlier you'd done a risk review and identified the wet pipe as the highest risk to be met with a "It'll never happen here". I'll take an unintentional mist release over a sprinkler activation any day thanks.

author: Halcyon
author_rank: Unknown
timestamp: November 01, 2017, 08:12:06 am
content: Quote from: BradC on November 01, 2017, 07:47:46 amYep, you're quite right. Even those big industrial air conditioning units which are designed for 24/7 operation in server rooms scare me after what I discovered...Many years ago when I worked for one of Australia's largest telcos at the time, I was part of the server/network admin team. We have a major data centre in Sydney which was largely storage for the rest of the sites around the country (by comparison it would be considered a small to medium sized server room these days).We had everything from tape libraries to microwave feeds and large (for the time) SAN racks. The problem was the it was all retrofitted inside a regular office tower, false floors and all.We experience two major failures...One was due to the fact that whoever had wired the comms/server room, had fucked up. As the company increased and more and more workstations were installed on that floor, meant that one of the three phases was being over-loaded. One night my phone went off with non-stop SMSs with servers and routers not responding. Turns out, the phase connecting everything was running red hot and tripped. The other two servicing the floor were cold with very little load.The other was due to a "WUF Error" displayed on the massive air chilling units for about 2 days (from memory they were Emerson units). No one (including me at the time) knew what the hell "WUF" meant. It was still blowing cold air, everything appeared to be normal (at least on the surface). We logged a service call but no one would be out that day.I was running cabling and had to pull up some of the floor tiles when I discovered what the "WUF Error" meant... WATER UNDER FLOOR! Sure enough, there was about 3 centimetres of water under all the racks with network cabling, 240v power outlets and cables feeding the UPS battery bank just swimming around down there. To this day, I'm honestly surprised nothing tripped or shorted out.Turns out, the chillers had been connected to the buildings regular sewer system which also services kitchen and bathroom sinks etc... It had become blocked so the water just started filling the server room.

author: Kilo Tango
author_rank: Regular Contributor
timestamp: November 01, 2017, 09:15:13 am
content: Just thinking for a house fire, how about connecting one of those foam things up to the front door. It would soon fill the place with foam and smother the fire.And as far as electronic equipment getting wet, a quick way of drying it might be just to leave it running. A few years ago I was working on an experimental Radar system in portacabins, racks full of TTL and a massive transmitting tube, all taking quite a few KW of power. Over a bank holiday the air conditioning went on the fritz and we came back to find it dripping in water, everywhere.Basically we just turned it on and fired up the transmitting tube. The heat soon dried everything and it still worked.Thing is if your equipment is turned on and using power, it will stay warm and so unlikely to get water vapour condensing there. It will be in the air circulating but it will stay there, so hopefully the air con will dry it.Ken

author: Brumby
author_rank: Unknown
timestamp: November 01, 2017, 09:27:16 am
content: I always think about one scenario when all this talk about fire suppression systems is in play...What of there is a human in the affected room?

author: Halcyon
author_rank: Unknown
timestamp: November 01, 2017, 09:32:54 am
content: Quote from: Brumby on November 01, 2017, 09:27:16 amUsually little to no impact.Back "in the day" when they used Inergen (I think it's still used today), you'd need to evacuate the room before the gas was released. It wasn't deadly, but it lowered the available breathing air in the room to levels which could be hazardous, but it was much less of a hazard than just CO2.A lot of (most?) gas fire suppressions systems now support human life inside the room, while quenching fires.Although realistically, unless you're engaged in fighting the fire or are otherwise unable to escape, most people would just leave the vicinity. Early warning systems and smoke detectors are very good.

author: tooki
author_rank: Super Contributor
timestamp: November 02, 2017, 05:51:23 am
content: Quote from: Cerebus on October 31, 2017, 11:38:34 pmSorry, I should have specified that I was operating under the assumption that this robot sprinkler was still intended to be attached to a sprinkler plumbing system — my comment was about using multiple traditional sprinkler heads as opposed to fewer of these things. (That was one of the selling points they claim.) If you’re already running sprinkler pipes to a room, then truly it’s just a few feet of difference to add another head in the same room. I wasn’t comparing it tono sprinklers at all.

author: timb
author_rank: Super Contributor
timestamp: November 02, 2017, 07:01:01 am
content: Quote from: tooki on November 02, 2017, 05:51:23 amRight, that’s another point is that these are designed to run off normal 1/2” domestic plumbing, as they contain built in pumps. Now, some might say that you’d still have to run said 1/2” piping into the rooms this will be installed in (bedroom, living room and so forth), so why not just install larger pipes and a regular sprinkler system. Well, you still need a central pump for that, also, it’s a lot easier to run a few feet of 1/2” piping up a wall (and simply tap it off the existing water pipes that run under your house) than it is to run new piping and fixtures throughout your ceiling.There’s also the point of a water misting system doing much less damage than traditional sprinklers should they go off by accident.At the very least, the version that installs onto the base of your kitchen faucets is easy to retrofit and would be very useful, since most home fires start in the kitchen, and it’s safe for grease fires.

author: Cerebus
author_rank: Super Contributor
timestamp: November 02, 2017, 02:52:32 pm
content: Quote from: tooki on November 02, 2017, 05:51:23 amI think then that it'smewho got the wrong end of the stick.

author: jmelson
author_rank: Super Contributor
timestamp: November 02, 2017, 10:11:16 pm
content: Quote from: sokoloff on October 31, 2017, 12:37:48 pmYup. We had a turkey grease fire in our home oven some years ago. We have a water/air extinguisher, which shoots a stream of water. So, we opened the oven door all the way, and I shot a burst of water at the back wall of the oven. This immediately flashed into a shower of droplets and knocked the fire down. A few more timed spurts and the fire was out. A stream of water right on the burning grease would have made a much bigger mess, for sure.Jon

author: jmelson
author_rank: Super Contributor
timestamp: November 02, 2017, 10:19:11 pm
content: Quote from: Kilo Tango on November 01, 2017, 09:15:13 amUh, no! We had a computer system in a building under an industrial-scale chemical engineering lab. They flooded the lab, and the ceiling started dripping all over the computer. Somebody there turned off everything he knew to turn off, but the disk drives stayed powered on. They had a housing closed on the bottom, and a backplane with, I think 50 V DC on it. (These were 40 MB 14" mountable pack drives, very old school.) Well, leaving the 50 V DC on there for a couple hours immersed in dirty water caused traces to be burned off the motherboard. The tech soldered heavy wire where the traces were burned off, and the drives worked fine! Amazing!The 30 KV circuitry on your radar transmitter was sealed for safety and EMI reasons. I can't imagine firing up a 100+ KW magnetron with water on the cathode terminals! KA-POW!Jon