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  1. #1
    Join Date
    Apr 2004
    Location
    San Antonio, TX
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    Question FOG & SMOKE MACHINES - TRIPPING SMOKE ALARM

    6/11/11

    Fog/Smoke Machines - Setting off Smoke Alarm

    We just picked up an account to do maintenance of a nightclub, approx 4200 sq ft., three package units. Our duct guys are modifying the supply to hit more of the dancefloor.

    Club has been in operation only since 9/10, so has not been thru a S. Texas summer yet.

    Don't know, but suspect fog machines been op for a while. Issue seems to be the units trip off line by the smoke alarm, and owner has been going up and cycling the disconnects when this occurrs.

    Have a number of things to address here, but has anyone had experience with such a scenario? I have to look up the fog machine specifics, I now nothing about them, but thought they ran on CO2 or water vapor. On the surface, doesn't make sense "fog" would set off smoke alarms?

    (will need the model #'s, but units are Carrier, Weathermaster about 5 years old and were cruising when I did a trouble call @ 130am this morning)
    G T T

    “In the end we will remember not the words of our enemies, but the silence of our friends”

    Martin Luther King, Jr.

  2. #2
    Join Date
    Jan 2009
    Location
    Indiana
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    3,228
    what type of smokies do you have?

  3. #3
    Join Date
    Apr 2004
    Location
    San Antonio, TX
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    Don't know right now. I will be there 3 hours before they open to do some stuff this pm. How many types of "smokies" are there?
    G T T

    “In the end we will remember not the words of our enemies, but the silence of our friends”

    Martin Luther King, Jr.

  4. #4
    Join Date
    Apr 2004
    Location
    San Antonio, TX
    Posts
    311
    OK just read an intro on the smoke/foggers. You got two basic types, heated oil or CO2/N/ Liquid air type. So, thinking a bit here, if it's a heated-oil type, possibility the oil particles "fool" the smoke detectors? Expect to see the fog machine in a little while, any pointers?
    G T T

    “In the end we will remember not the words of our enemies, but the silence of our friends”

    Martin Luther King, Jr.

  5. #5
    Join Date
    Jul 2001
    Location
    Southern NJ
    Posts
    1,241
    All the smoke detectors I'm familiar with "see" smoke when the smoke blocks either a light beam or a beam of radiation.

    I would suspect that even fake smoke could do this.
    Ryan
    Maintenance Guy
    -----------------
    naysayer, skeptic, conspiracy theorist

  6. #6
    Join Date
    Aug 2006
    Posts
    2,593
    Radiation ones will be less likely to see the Fog, than the Photo ones. A lot of modern smoke detectors use both sensors in their units. This is one for the Fire Alarm folks to cure, and it is curable. Don't step out of your trade and get yourself in trouble.

  7. #7
    Join Date
    Jul 2009
    Posts
    247
    Most fog machines i've worked with have been of the heated type, although I think theres more water than oil in the fluid. The fog machines' nozzle heats up to some ungodly temp and a pump forces the fluid through a tiny pinhole in the nozzle, and the fluid vaporizes immediately. Depending on the fluid and/or the fogger, the results will either be a very dense fog, cant see your hand in front of your face type of fog or a very light, more of a haze fog.

    And i'm gonna have to agree with madhat, see what the fire alarm guys have to say.

  8. #8
    Join Date
    Sep 2009
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    S.C.
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    Quote Originally Posted by maintenanceguy View Post
    All the smoke detectors I'm familiar with "see" smoke when the smoke blocks either a light beam or a beam of radiation.

    I would suspect that even fake smoke could do this.
    Hummm... Kinda backwards. In all the Optical ones I've ever seen the sensors (send and receive) Do No point at each other, when smoke, dust, powder or most anything airborne enters the detector it causes the light to bounce and it will end up in the receiver.

    I think they are going to have to change the Optical or an Heat type sensor and you'll be good to go. (I would suggest calling the Insurance Company to be sure they approve prior to making any changes.)

    Yes, I know I Shouldn't But I Just Can't Help Myself...

  9. #9
    Join Date
    May 2007
    Posts
    732
    We had an installation in a bakery where the duct smoke detectors were tripping intermittently. I know, this is not the same environment as fog/smoke machines in a bar but since we learned something I will add this to the thread.

    The detectors giving nuisance alarms were ionization type. I googled "ionization versus photoelectric smoke detectors" and got a number of relevant hits. The documentation is all very scientific, boring, slow reading but the consensus was that ionization detectors will have more nuisance alarms. There are caveats to that general statement, I leave it up to you to read the documents and make your own analysis.

    We changed to photoelectric detectors and stopped having nuisance alarms.

    In nutshell, ionization detectors respond slightly faster to flaming fires, and photoelectric detectors respond slightly faster to smoldering fires, which is why there are detectors with both types of sensing. But either type will have an adequate response time to either type of fire. When detector type is not specified in contract documents or is left up to the installer, more ionization detectors are used in ducts simply because they cost slightly less.

    Of course the local authorities and the insurance company may have a final say. In this installation where we had the problem either type was acceptable.

  10. #10
    Join Date
    Feb 2006
    Location
    Atlanta,GA.
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    877
    it may be the water vapor creating a short in the detector i have a building that has a lab in it that must maintain 70 degrees with 65% humidity humidty kept causing smoke detectors to go off due to water on them changed smoke detectors in the lab area to heat heads been fine

  11. #11
    Join Date
    Feb 2009
    Location
    New Orleans
    Posts
    40
    A Google search for "fog machine smoke detector" will show you that this is a very common problem. Depending on the type and amount of fog they are producing, it may not even be possible to stop this from happening short of bypassing the alarms... (I will assume you are not insane and actually considering that in any way shape or form).

    Anyhow, I agree with the person above who said let the fire alarm guys deal with this. It's nothing but a potential headache for you.

  12. #12
    Join Date
    Sep 2009
    Location
    S.C.
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    Hummm... I had an Ice Machine that was tripping out in an Factory Office and sent the helper to get the Nitrogen. He came back and I proceeded to Blow the Coil clean and then I noticed a Smoke Detector just behind my head (and thought, "Crap... Big Mistake but maybe..." at that very second the Smoke Alarm lights on the walls started Flashing and then "Honk... Flash... Honk.... " Yep, the dust out of the Ice Machine set the Fire Alarm off.
    Yes, I know I Shouldn't But I Just Can't Help Myself...

  13. #13
    Join Date
    Nov 2004
    Location
    Georgia, USA
    Posts
    10
    I had the same problem in a group of meeting rooms. Got permission from Fire Marshal to disable the smokes for that room only during concerts. With adquate personel for fire watch. We had to do a program to make sure system was back to normal after the concert.

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