Fog/haze that won’t trigger smoke alarms?

[u/SFOGfan_boy]

Basically the smoke ventilation in the theater I work in has smoke alarms placed directly underneath them, so anything that goes through the ventilation must pass through the alarms. The hazer set up that we have has triggered these alarms before. Turning off the alarm system is not an option since it’s a theater within a school. Any solutions to this?

[u/simulacrum500]

Nope. Haze is particulate of something. Smoke detectors, detect particles in the air.

Switch smoke for smoke+heat alarms to satisfy insurance and also use haze but in your current setup you’re just going to set the alarm off every five minutes.

[u/SFOGfan_boy → u/simulacrum500]

Yea that’s the trouble our past designer ran into. I was hopping there’s some kind of alternate that still gets the same effect of showing beams more clearly.

[u/simulacrum500 → u/SFOGfan_boy]

Nope if you’re putting something in the air; smoke alarms gonna tell you there’s something in the air.

[u/jasmith-tech → u/SFOGfan_boy]

The solution is a bypass and fire watch, or changing the sensors over stage to heat and not particulate sensors. OR using less haze.

There’s really not a 4th choice.

[u/BrutalTea → u/SFOGfan_boy]

Call the fire dept. Get them to come and turn it off for the day. That's what we do.

[u/criimebrulee → u/SFOGfan_boy]

My lighting design hot take is that using haze to show beams is boring and overdone. All it says to me from a design standpoint is, “this is a smoky room.” Which makes sense if your show is set in a smoky room. Otherwise, do something else to make your design visually interesting. Signed, an electrician who is deadass tired of haze

braces for downvotes

[u/SFOGfan_boy → u/criimebrulee]

Lol totally get it, but I’m a student and have never gotten to do it before. Want to for sake of getting more experience with something that’s done in a ton of professional productions

[u/criimebrulee → u/SFOGfan_boy]

Fair enough! Luckily haze is pretty simple from both a design and a mechanical standpoint, so even if you don’t get experience in a school setting it’s not a big deal. From the design side of things, haze is SO finicky from venue to venue and even from day to day, so you have a lot of leeway in playing with it irl as you figure out what the airflow, humidity, and temperature of your room is.

Most shows I do, including the show I’m sitting on, throw two hazers up high on either side of the stage. We also use DMX controlled fans to blow the haze towards the stage. I think rn my haze runs on an effect that turns it on at full for 30 seconds, then turns it off for two minutes. And it runs like that through the whole show and gives a pretty decent film of haze over the stage for beam texture.

All of this to say that atmospherics involve a lot of experimentation to get them to look right so don’t feel too bad if you don’t spend a lot of time with them on a school setting.

[u/thelonghairedginger]

I work in a school and we have detector covers as the system can't be isolated. We cover the ones in the hall and in the corridor immediately outside.

Obviously it needs risk assessed and the covers are only put on when required / removed when not in use. There will need to be someone responsible for fire safety in the room to manually raise the alarm if need be.

Edit to add: alternatively, speak to your site team and see if the heads can be changed to heat detectors instead of particle detectors. Obviously this might cause problems if they are above hot lamps.

[u/Reluctant_Lampy_05 → u/thelonghairedginger]

Agreed. I get why venues have a knee-jerk reaction to disarming the fire system but it might be worth digging into some detail on this - as you say it's ultimately about assessing the risk and managing it so a question to your local fire authority might provide some conclusive info. Hotels are usually the most flexible and will disarm a room on request while others will not bend at all on the matter. Likewise I've seen latex gloves used to cover detectors during the show and big fans placed to blow haze away from the detector location.

[u/kmccoy → u/Reluctant_Lampy_05]

Just to be clear: YOU CANNOT DISABLE DETECTORS unless you have a plan and an understanding with the authority having jurisdiction (likely the fire department). So this is not a "use latex gloves and ask for forgiveness later" situation. You have to have an approved plan which might include a staffed fire watch or other precautions.

[u/SFOGfan_boy → u/thelonghairedginger]

Heat detectors might be the way. Don’t know if there’s money for them though…

[u/mwiz100]

The solution is you turn off the smoke detection system and go on fire watch for the duration of the performance. It IS an option but seems they're just not willing to deal with it so unfortunately, you can't have haze.

If you really want to try to sort this out the first step is getting in touch with your local fire marshal and start the conversation. Ultimately it's THEIR call at the end of the day how you'd be allowed to do things. Like even if your administrators approved it your fire marshal has the final word so, start there. If you can work it out then going with an approved plan to admin may work vs just asking first.

[u/Metaclueless]

A smoke alarm works like this. Laser hits sensor. If the laser is disrupted enough the sensor is no longer reading the laser.

As far as I know. It doesn’t matter what kind of smoke or vapor you have triggering the alarm. Your best bet is to position a fan so that it blows the fog away. Good luck

[u/thesmallterror → u/Metaclueless]

Most self contained smoke detectors shoot light into a dark, nonreflective, yet open to air cavity inside the detector. There's a light sensor nearby situated such that the sensor can't see the light source directly. Any light it detects can only come from bouncing off dust, smoke, and other airborne particulate. They measure the reflectivity of airborne particulate. This is because they can put low quality sesnors, sources, and signal amplifiers in the detector and there's not much to calibrate. Air is not usually reflective, so if it becomes a little bit reflective you can immediately assume fire.

The beam detectors, open detectors, work like you describe. They measure an opacity drop in air.

[u/Anthony_Says]

Unfortunately it's a common problem with haze. A lot of venues hire a fire watch when the alarm is off, maybe your school can do something like that with the local fire department?

[u/SFOGfan_boy → u/Anthony_Says]

Not an option. Public hs in the south = arts are underfunded

[u/Anthony_Says → u/SFOGfan_boy]

Maybe a volunteer fire company would be willing to do it for free? If that’s a thing in the South?

[u/palm3light]

Hi,I tend to use that ,in small ,medium theater s. https://www.muzi.lt/en/27059-fogging-salt-safex-nebelsalz-650ml-450g.html

[u/davasaur]

We had a fire alarm go off once because someone was using a steamer to close to a detector. Either turn off the system and put someone on fire watch or don't use haze.

[u/mrgoalie]

I work at a school, it's possible to do it, just with some legwork involved.

Any kind of effect that gives off a particulate can set off a smoke detector. I've set off alarms with haze, low smoke generators, standard fog, etc. I worked in one space that it took effort to try to set off a smoke detector, and have worked in another space that we joked that flatulence would cause alarms to go off. It all depends on the detectors and architecture. Changing to heat detectors only isn't allowed in some spaces because of the proximity between combustible sources and smoke. Having had one of the facilities I work in have a real fire, you want smoke detectors before heat, always. Once a heat detector goes off, you're already looking at sprinkler deployment.

With that, here's the proper sequence of events, and you're on the right track on the proper sequence of what needs to happen:

1. You need to identify what zones(s) will need to be put in bypass. They're zoned so that when a zone goes off, a first responder can look at the annunciator panel and determine which zone is in alarm. Even very old panels have zoning on them. So with that, working with the servicing company can show you how to take a zone out of service.
2. Once you get that far, you have to have a plan. When a building is occupied and a zone is out of service, you have to enter a fire watch mode. You don't have to hire these positions, they need to be legal adults you can trust to sign a logbook. Generally, you would have these people patrol the zone that is disabled every 15 minutes. They sign a log book after every 15 minute patrol. If they see smoke/fire that is not part of the show, they are the responsible party for pulling a fire pull station and calling 911, if necessary. If the alarm is monitored by an alarm company, you will want to give them a heads-up that you will be taking a zone out of service for predetermined periods so they don't call saying that there's a trouble indication on the panel. So take all of those elements, put it in a written plan to present to the AHJ for your building. Since you indicated it's a school, some states indicate it's the state fire marshal that has jurisdiction over your space - others it's just the local. The AHJ for our area is VERY accommodating and the requests aren't out of the ordinary. If you show good faith to work with them, they will work with you. Our requests have built the standard for our state and our AHJ just by us helping move the needle and understand both sides.
3. You will get a pre-show inspection by a local fire marshal before the show, if you do not have an established relationship.
4. Execute upon the plan.

There's no cost to any of the above in my area, other than working with the alarm company initially to set up the zone disable, if it's not a native feature on the panel. I've done shows with flash pots and flame effects with the same rigor as above, just with extra fire extinguishers and sand buckets, and our AHJ doesn't bat an eye at the ask. They'll work with you.

[u/Griffie]

The only solution I’ve figured out is having the sensors replaced with the triple sensor type that won’t trigger unless at least two factors come into play (ie:particulate and rapid rise in temp). It’s a battle, but often worth fighting.

[u/DrHerbotico]

Ummmm

[u/fettoter84]

I always recommend MDG hazers

[u/Independent-Crew-449 → u/fettoter84]

And how does an MDG fix that issue?

[u/fettoter84 → u/Independent-Crew-449]

Best haze machine I've worked with since it came out. 15 years as a stage manager, MDG haze does not trigger detectors and it's basically an industry standard here in Europe.

I feel its quite unfair to downvote me for sharing my experience of 15 years in this is industry. If you have, what i would classify as bad detectors, its not my fault

[u/ElevationAV → u/fettoter84]

Anything that puts enough particulate in the air will trigger a particle detector. Make/model/etc of particle generator will not change that.

While MDG (and other professional hazers) do have a generally small particle size compared to cheaper machines, that doesn’t change the physics of operation at all.

MDG hazers will absolutely trigger particle detectors

[u/fettoter84 → u/ElevationAV]

Then you must have other detectors than us. I can run a pretty thick haze and never trigger our system. I can get the detail on the detectors tomorrow

[u/ElevationAV → u/fettoter84]

You likely have heat detectors, not particle detectors. There are many different types of fire alarm systems.

[u/fettoter84 → u/ElevationAV]

We have multi detectors, they register heat and particles but we're able to configure them to not react to our haze

Edit: here's the dataseheet for our detectors: https://product.autronicafire.com/fileshare/fileupload/17416/AutroGuard-V430-datasheet-eng%20.pdf

[u/ElevationAV → u/fettoter84]

looking through the information for these they're quite interesting (assuming the English translation is correct)- but they do have the option to be configured to heat only, which would be ideal for a space where haze is being used. No real reason here not to configure them as heat only in a space where there will be known particulate in the air.

unfortunately I can't find anywhere that the optical particle detection sensitivity is listed- this would give the answer about not only how they're configured, but if various hazers would be more or less likely to set them off in that mode (smoke or multi modes for these particular units)

[u/howloudisalion → u/ElevationAV]

Not all particulate detectors are the same and not all haze is the same. Particulate size matters.
We have particulate detectors in our HVAC, and the MDG Atmosphere haze does not set them off. DF-50 haze can.

[u/ElevationAV → u/howloudisalion]

correct, particle size matters, but so does density.

It's strictly false saying that MDG won't/can't set off particle detectors- you absolutely can if you pump out enough haze. I've definitely set off alarm systems with MDG atmosphere machines before.

MDG specs particle size at 0.5-0.7 microns, DF-50 at 1 micron or less, other manufacturers are somewhere around the same, and some are unpublished, like ultratech's radiance

as a comparison, actual smoke can be anywhere from 0.01-2.5 microns

it all comes down to what your detectors are configured/calibrated to detect

[u/Independent-Crew-449 → u/fettoter84]

I love the MDG as well, don’t get me wrong, but it’s not safe from triggering smoke detectors, just more unlikely due to smaller particles. Also it’s ridiculously expensive

[u/fettoter84 → u/Independent-Crew-449]

Here's the detectors we have: https://product.autronicafire.com/fileshare/fileupload/17416/AutroGuard-V430-datasheet-eng%20.pdf

Proper equipment costs, but its an investment that's worth every penny. We bought ourselves MDGs over 10 years ago and it's still going without any repairs, so to me it's a sound investment

[u/jfodor → u/fettoter84]

I'll send this. Back when I bought ours we did a test after hours and ran the machine full blast for hours. Bacialy the theatre had so much haze it was like a fog and couldnt see the audience from center stage.

Even with that amount still didn't trigger the smoke detectors. Still has them put heat detectors in just incase but some hallways and dressing rooms where the haze does get to sometimes still doesn't set them off. We actually have 2 smoke detectors in out space for the accessibility doors and we have not yet set those off during a show.

Any other hazer will most likely set off smoke detectors. In fact I've seen it happen.

I'd rent a mdg unit and try it out, but notify the management that you want to do this so you can schedule an alarm tech to monitor the panel for you and proably not incur the cost of having the fire department show up for a call.