Fog machines and smoke detectors

Was lookin at buying a fog machine and was just curious if it will trip my smoke detectors. I don't want to spend money only to find it causing the fire department to show up on my doorstep lol.

Any input would be great!

Thanks

I have never had it trip my smoke detector. Don't smoke detectors dectect carbon in the air?

The battery operated ones are set off by fog machines, I don't know about ones built in to a system.

Regards rog8811

The smoke detectors at my house are line-voltage wired and they trip from my fog machine. They're not very sensitive to it though so as long as you unplug the detectors in the rooms you will be fogging it will be ok.

Smoke detectors can either be ion chamber based or optical.

Ion chambers have a little bit of radioactive material that sets up a charge in a little chamber. Any airborne particles like smoke and fog droplets disrupt the charge and the alarm goes off. Optical smoke detectors work simply by shining a light on a sensor - any smoke or fog reduces the light that hits the sensor and the alarm goes off.

It seems that over the last few years, many of the venues we play private gigs at (weddings, corporate events, etc) have adopted a "no-fogger" policy, generally the issues cited are residues (common to old oil hazers and cheap, glycerine-based fog fluids) and/or the potential to set off sprinklers ... In the 5 years I have done music production as a full-time job, as well as the 12 years prior to that when I was doing it part-time to suppliment my income, I have NEVER seen a sprinkler of smoke alarm set off in a club by fog (even really, REALLY heavy fog).

I would imagine there are smoke detectors based on optical sensors (airborne particulates, etc) that could possibly be tripped by a fogger, but those would be in places where ANY source of ignition would be strictly prohibited - try not to book any gigs in a grain elevator or production painting plant and you should be just fine squirting a little fog for your lasers just about anywhere!

SIDE NOTE: If you are using a heat-type fogger, I highly recommend either MARTIN I-Fog or FROGGYS Swamp Juice instead of the crap they give you with the fogger or the American DJ/Chauvet crap that most music stores and costume places sell. You will spend a bit more ($35/gal shipped as a rule) but you will use MUCH less of it due to efficiency, better dispersion and hangtime, etc and the added bonus is the good clean quality fluids kepp you from having to clean your machines as often or worse, throwing them away because they're clogged...)

OR - Buy a Martin or LEMaitre haze generator, residue-free, very controlled room dispersion, and a gallon of haze fluid will last you 6 months even with a 4 night + a week schedule (trust me!)

(Oops - I thought we were talking commercial venues, not something as confined as a room - shoulda read more first, sorry!)

Oh, and considering the hazers I mentioned are capable of 10K cubic feet plus per minute at wide open throttle, might wanna forget that part too, sorry!

rog8811 said:

The battery operated ones are set off by fog machines, I don't know about ones built in to a system.

Regards rog8811

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I have never had one set off by a fog machine...and I had the room filled with so much fog, you couldn't see 5 feet in front of you!!! Maybe yours are just ultra sensitive.

I had the room filled with so much fog, you couldn't see 5 feet in front of you!!!

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When I was decking out one of our rooms as a haunted house for halloween on my first test the smoke alarm went off within seconds of the fog machine being cranked up..... I found removal of the battery solved the problem. :

Regards rog8811

same, i always remove the batteries first...

rog8811 said:

I had the room filled with so much fog, you couldn't see 5 feet in front of you!!!  

Click to expand...

When I was decking out one of our rooms as a haunted house for halloween on my first test the smoke alarm went off within seconds of the fog machine being cranked up..... I found removal of the battery solved the problem. :

Regards rog8811

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Really,,....Maybe there was something wrong with mine.? :-?

Well i think ill just take the batteries out of it, and im not planning to do this in a room in my house, its going to be in my basement. Its nothing serious, just wanna get some really nice beam shots.

Thanks for the input

Another option is covering them with a shower cap.

Earlier smoke detectors use a collimated LED beam on one end and a Cadmium telluride photo-diode on the other end...any airborne particle that drifts between the two with sufficient density of obstruct light, changing the signal voltage of the photo-diode [or, if its a cadmium sulfide photo-resistor, then a sudden change in resistance] and trips the alarm...
Then there was a Gen II that was much less sensitive to airborne dust. The photo-diode is mounted perpendicular to the beam of the light. The theory of operation goes that when theres sufficient dust in the atmosphere light will scatter and some will hit the photo-diode and trips.

But now everything made in China, a cheaper but more technically-difficult-to-understand version came about using a small unit of a specific radioactive isotope [usually Americium-241, half life 432.2 years...aren't you glad they didn't use Americium-243 with a half life of 7370 years? :] in an ionization chamber with two electrodes separated like a capacitor and a low current bias across the electrodes. incoming smoke or other airborne particles will absorb beta [or was it alpha? :-/] particles and break the ionization and therefore cuts off the current flow between the electrodes...creating an open circuit and will scream like a banshee until its removed.
Occasionally a quick spray of canned air can alleviate the squee...but other times the ball peen hammer comes out and...and never never trust the hush button will work when you need for it to work

Whether or not it will depends on a couple different things.

***Dimensions of your room***
+fog will quickly distribute itself on the floor...under the assumption what your using [glycerin] is denser than air and therefore clings to the ground, it will take some considerable time for it to reach the detector if theres room on the ground to faciliate its expansion

***Nearest source of airflow***
+While the fog is rolling around, if your HVAC utility is running [AC/heat/fan] the fog may circulate in the room and if your alarm is in the path of it...then yes

***Sensitivity of your alarm***
+assuming that its the ionizing version [if you see a black cylinder beside the battery tray it most likely is] the proximity of the electrode/plates and the current stability of the forward bias. the farther the plates the less sensitive it is.

Of 8 alarms one kidde brand was way too sensitive and would go off in the hall after I took a hot shower and opened the bathroom door...and its also the fastest battery drainer in the house. I finally got ticked off one day and took it outside, lay on ~10mg of powdered magnesium on it then...

But anyway, with sufficient fog within close proximity of the smoke alarm...it will go off. As mentioned above...with our current smoke alarm technology we have not been able to create something that distinguishes between smoke and other pollutants :-?

I have found that covering a smoke detector with a latex glove work well.

pamperchu said:

I have found that covering a smoke detector with a latex glove work well.

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I'm surprised to know it can stretch to that size

lol i did a laser show up at the school for Halloween and we had a fog machning. this was in the cafeteria and its a pretty big area. well after about an hour the fog i gues got so thick it set off the fire alarm in the school...... ya so not cool lucky it didnt activate the sprinkler because their set on a delay and we were able to get it shut off in time ......