Fire alarms vs. haze...

[Andrew C]

Further more the isolate will be a key (or possibly a code I think some places) thus insuring only authorised persons can isolate it.

Ours requires both key and code. The complete @rse of it though, is that each head needs isolating individually. Auditorium ceiling *a few, loft space * a few (open to the stage), under stage, wings etc. It takes about 1/2 hour each way; thus Works sparkies hate doing it and are as obstructive as possible to each request.

[niclights]

Our club has heat detectors. They are connected the same, its just a different type of sensor. They require both heat & smoke to set them off. Just get the sensors changed.

We can still have a problem with ours as we are a rave. Lots of sweaty ravers jumping around produces a lot of heat. I've put big signs near the controller now to warn trigger happy dj's.

They measure how fast the temperature changes. Lots of people in a room cannot set them off.

[dbuckley]

At a theatre at another BR member nearby they have what is a low tech and neat system - in the lighting booth there is a mechanical 30 minute timer which isolates the smoke detectors. The Stage Manager has 'wind the clock up' cues in the script to ensure that the override doesn't get disengaged mid-performance.

 

SOunds much less grief than some systems described herein.

[Blaize110]

Ours requires both key and code. The complete @rse of it though, is that each head needs isolating individually. Auditorium ceiling *a few, loft space * a few (open to the stage), under stage, wings etc. It takes about 1/2 hour each way; thus Works sparkies hate doing it and are as obstructive as possible to each request.

 

Yeah, ours are the same. Luckily we have a very nice and obliging caretaker. And I agree with Grahame that it is VERY annoying when people dont even make an effort, even after being told well in advance. Also the paranoid people who dont believe that there are different types of smoke alarm and that if you so much as think the word 'smoke' it might go off.

 

Though this does remind me to go and check with someone what kind we have in the school. Might save people a lot of unnucessary work if they are the heat kind.

[GridGirl]

At a theatre at another BR member nearby they have what is a low tech and neat system - in the lighting booth there is a mechanical 30 minute timer which isolates the smoke detectors. The Stage Manager has 'wind the clock up' cues in the script to ensure that the override doesn't get disengaged mid-performance.

 

SOunds much less grief than some systems described herein.

 

That would be my venue, and it works like a charm (although we have just had to replace the timer because it was jamming on at 15 minutes!). I should also add that we are in a heritage building, so the restrictions are even tougher (hence the 30 minutes only) but all the relevant authorities are happy with our solution. Another theatre in the city has a simple push-button switch side of stage which isolates all the in-auditorium detectors for 3 hours - there's a whiteboard above it where you write the time you isolated and again, everyone is happy.

[adam2]

Several posts refer to some variety of timer, whereby smoke detectors may be isolated for a set time, and then automaticly re-instated afterwards.

Such schemes sound excellent, since they preclude the smoke detctors being left isolated.

 

My only concern would be WHICH detectors are isolated, I would be uneasy re isolating smoke detectors in empty areas, since any fire in such in area could reach serious proportions before being noticed.

 

Providing however only detectors in the performance space are isolated, then the idea has much to commend it.

[jagardner1984]

Many of the newer spec venues I have toured to recently have heat detectors in the theatre and Smoke Detectors outside. Is that not a sensible way forward ? Removes the need for any kind of manual intervention.

[adam2]

Many of the newer spec venues I have toured to recently have heat detectors in the theatre and Smoke Detectors outside. Is that not a sensible way forward ? Removes the need for any kind of manual intervention.

 

Yes I believe that this is the way forward, for new venues or those being equiped with a new fire alarm.

Not much help though for those stuck with existing systems.

 

Heat detectors have two drawbacks compared to smoke detectors.

 

1) They do not detect fire nearly as quickly, a small smouldering fire, or even overheating materials or equipment that are not yet on fire, will operate a smoke detector quickly.

A heat detector cant be too sensitive or false alarms will occur from lamps and heating equipment.

Therefore a fire can reach serious proportions before a heat detector operates.

 

2) A full test of a smoke detector (not just testing the wiring to the detector) requires the application of smoke, or a suitable substitute. This is easily done with canned smoke applied by a long reach tool, sold for the purpose.

A full test of a heat detector requires the application of heat for test purposes which is more innvolved.

 

The reduced sensitivity of heat detectors compared to smoke detectors is most unlikely to endanger life in a performance space since any outbreak of fire should be obvious.

It could however increase the risk of fire damage and might increase insurance premiums.

 

The ideal system in my view would be sensitive smoke detectors that include a PIR motion sensor.

These would be configured such that if movement is detected, then the smoke detector is disabled until say 5 minutes after the last movement.

This would permit the use of smoke in occupied premises without risk of false alarm, and also be valuable in kitchens (burnt toast) and workshops (soldering, angle grinding)

 

Once the area has been vacated for say 5 minutes, then the smoke detector would be re-activated and give valuable early warning of fire in empty premises or empty areas of partialy occupied premises.

 

AFAIK no such product exists. Is this a business oportunity ? there would appear to be a substantial demand for such detectors, both stand alone battery operated ones for d0m3stic use, and ones suitable for a central fire alarm panel.

[niclights]

I had no problem changing all our original smoke to heat detectors in performance and adjacent areas. AFAIK only the more inaccessible areas such as roofspace/plant remain smoke. This was all easily approved.

[Andrew C]

Have a look at the newish sophisticated detectors available, this is better than plain "rate of rise" systems, or isolation.

[Goodsparks]

In analogue systems, multi-sensors will probably provide the most accurate form of detection in this type of environment. The detectors incorporate both smoke detection (usually optical) chambers and thermal sensors. There are a number of different algorithms that will cause the head to go into alarm depending on the heat/smoke combination/time. Alternatively most decent FA panels will have day night mode which could be programmed with the multisensors to provide day/performance mode with heat detection only being active during performance times.

 

If smoke detection has been installed as a building regs requirement to compensate for structural deviations (excessive compartment size, travel distance, occupancy/capacity, construction materials) or if the FA uses cause and event to release secure doors / magnetic hold opens, first knock of drencher systems, open smoke vents.... then you really need to get some guidance from a competent fire engineer (not fire alarm engineer) prior to removing / changing or isolating any automatic fire detection.

[schooltechie]

in my old school the premises always told us that it was against his public liability insurance to isolate zones. We were never allowed to use smoke machines or pyro until recently where they flatly refused to use the smoke machine but said we could try the pyro and if it didn't set the alarms off we were allowed to use them. We tried this and no alarms so after years of being told they are smoke detectors they are obviously heat detectors.

 

Alex

[Grahame]

Have a look at the newish sophisticated detectors available, this is better than plain "rate of rise" systems, or isolation.

Correct me if I'm wrong, but I think that these are the ones that are the most troublesome with haze, Andrew; they measure smoke density in the air but can't distinguish between carbonised particles from a fire and water-based haze particles.

[Andrew C]

Going on a demo, I'd guess not. The Reptile showed how the head could be programmed to detect the 'smoke' particles, and wait until either the CO level, or "Rate of Rise" confirmed a fire before triggering. ISTR that the thresholds were variable; however it was a few years back that I was looking into this. (Nothing has happened from a purchase PoV since)

[sleah]

I would point out to those in charge that the main purpose of smoke detectors is to give warning if fire breaks out in UNATTENDED premises, or unattended/seldom visited parts of premises.

They also give valuable early warning in homes, hotels and the like where persons would be sleeping and liable to be killed by smoke without waking.

 

However in a well occupied area such as a performance space, smoke detectors serve no purpose whilst the premises are in use. Any outbreak of fire will be obvious to the occupants, who can evacuate, and operate "break glass" fire alarm call points on the way out, so as to warn occupants elswhere in the building.

 

Therefore I believe that isolating smoke detectors in a performance area is acceptable providing that all the following conditions are met.

 

1) That smoke detectors in other areas remain operable, for example stores, workshops, mess rooms, dressing rooms,offices, plant rooms etc. Any outbreak of fire in such places might not be noticed, and unoticed could be a serious danger. Early warning via smoke detectors, or other approved means thus being vital.

 

2) That all manuall "break glass" fire alarm call points remain operable.

 

3) That a clear written procedure exists to reinstate the smoke detectors before the premises are left either unattended or with only limited occupants.

 

I believe that this is EXACTLY right! Point out to the jobsworths who know NOTHING about fire alarms systems and legal (or not) requiremets that by the time the detectors in the auditorium are triggered, the fire alarm will have been triggered manually, or people will already be dead.

 

The only thing you could do, perhaps, is to try to present them with a proposed solution in terms of a well-thought-through method of isolating the auditorium and surrounding fire alarm zones - only a very limited number of people authorised to carry out the operation at the fire alarm control, a log must be filled in and signed each time the system is isolated, a nominated person(s) is responsible for reactivating the zones at the end of each show (e.g. FOH manager, security guard doing lock-up, performance fireman). Perhaps the fire alarm system even has a facility to reactivate all zones after a certain period of time - I believe some do.

'Better' fire alarm systems (i.e. newer ones as fitted to large buildings) can certainly rearm themselves after a set time period and also even print out a log of when they've been disarmed as well, saving you doing that manually (they also store this log so it can be accessed at any time by fire officers \ building services types). Further more the isolate will be a key (or possibly a code I think some places) thus insuring only aurtherised persons can isolate it. All I have seen or heard of continue to respond to their break glasses whilst isolated.

 

I work in a split site school, on one site the system has been upgraded to a system that works just like this... the sensors in the auditorium (hall :unsure: ) can be isolated, either fully or timed, by key and code. Ideal solution :blink:

 

Hmm... legalities. I doubt there is any legal requirement to have a fire alarm system fitted, at least not an automatic one. It is usually an insurance requirement, and therefore a local officialdome requirement. It's quite likely it IS a requirement in new builds - I'm just thinking of existing systems.

In our school on the 'other' site where the system hasn't been upgraded there are no sensors, only manual trigger points. Is the building illegal? Should it be closed with immediate effect? NO! Why? Because the fire officer and insurance company are satisfied there is adequate protection - that is, enough people around with common sense!

 

Pet hate: (ooops wrong forum but hey ;) )

It begars belief how it's those with responsibilty who are clueless. How can someone who designs a fire alarm system for a building be so clueless about the buildings function and what type of system is needed?

And worse, how can someone with responsibily over fire safety (building manager/caretaker/fire officer) be so clueless about the progress of a fire and how people should/will react?

:blink: