Short answer: yes, it can. An optical smoke detector measures how particles in the air scatter light, and it cannot tell a glycol droplet from combustion smoke; beam detectors and aspirating systems are even more sensitive. The fix is not to switch zones off at the panel. Turkey's fire safety regulation, the Binaların Yangından Korunması Hakkında Yönetmelik published in the Resmî Gazete of 19 December 2007 (No. 26735, decision 2007/12937), requires fire detection and alarm systems to be kept in working order, and when a system is out of service for any reason it requires extra security staff to patrol the unprotected areas until it is back. What actually works is simpler: tell the venue about the effect early, test it on load-in day with the air handling running in show mode, and write down the result. Below, the relationship each effect has with the venue and its detectors: fog, haze, low fog, CO2 jets, confetti and snow.
Fog, haze and low fog are not the same thing
Three products, three behaviours. A fog machine heats a glycol or glycerin based fluid and produces a dense, visible cloud that thins out within minutes. A hazer leaves a much finer mist. Its job is not to make a cloud but to make light beams and lasers visible, which is why it stays suspended for hours and is the hardest one on detectors. Low fog sits on the floor and is made with dry ice or with fog chilled by liquid carbon dioxide or nitrogen. Dry ice turns straight into gas at roughly minus 78.5 degrees Celsius at atmospheric pressure, skipping the liquid phase entirely. The ANSI approved ESTA standard E1.23 lists the materials used in these effects one by one: glycols, glycerin, white mineral oil, water, liquid nitrogen, liquid oxygen and liquid carbon dioxide. If the quotation does not say which one will be used, your correspondence with the venue starts incomplete.
Why does a fog machine trip the alarm?
A detector does not see smoke, it sees particles. A point type optical detector measures the light scattered by whatever enters its chamber, and a glycol droplet looks a lot like a combustion product in that measurement. Beam detectors send light from one end of the room to the other and react as airborne density rises, which is the usual solution in high ceilinged ballrooms. Aspirating systems draw air continuously through pipework and pick up very low concentrations; you meet them in concert halls, museums and heritage venues. Heat detectors are unaffected by fog because they watch temperature. The second variable is air handling. The explanatory part of E1.23 notes that heating and cooling equipment can carry fog from an area where it does not trip detectors to one where it does, and it asks for testing to be done with the air handling in performance conditions. The same section adds a warning worth remembering: detectors may not trip immediately, so wait at least 20 minutes after the test.
Can detectors be isolated, and who decides?
The organiser never touches the alarm panel. Article 67 of the Turkish regulation requires detection and alarm systems to be kept operational, and its third paragraph puts periodic inspection, testing and maintenance on the building owner or manager. Article 74 requires the detection system to be operated in line with TS EN 54 and, where a system goes out of service for any reason, it requires patrols by additional security staff in the unprotected areas until the system is restored. International practice points the same way. ANSI E1.23-2010 (R2015) prohibits interrupting detection during a temporarily installed fog effect, with a single exception that applies only when three conditions are met together: approval of the authority having jurisdiction, approval of the venue owner or the owner's agent, and an approved fire watch on site capable of directing every detection and life safety system in the building. The standard also requires the systems to be returned to normal as soon as the risk of false alarms has passed. Venues hold this line for a reason: according to İstanbul Metropolitan Municipality fire department figures, the city saw 27,820 fire responses in 2025, with an average response time of 7 minutes 2 seconds.
How do you plan the test?
E1.23 makes testing mandatory. The effect is run before the event under conditions as close as possible to the real ones, confirming that critical visibility is not lost and that the aerosol does not drift into unintended areas. The standard also lists the conditions that matter: lighting, heating, cooling and ventilation air flow, and the placement of scenery and personnel. For haze effects, monitoring during the event is accepted in place of a pre-event test. On site the sequence runs like this. The venue's technical manager and the alarm maintenance contractor are present, the silence and abort procedure is agreed beforehand, the monitoring station is informed if the system sends an automatic call to the fire brigade, the fog is increased in stages, and everyone waits 20 minutes after the test ends. Then write it down: time, fluid and quantity used, what happened in which zone, who was in the room. That short note ends the argument when the same question comes up again on show day.
Fog must never hide the exit signs
The standard is blunt here. Aerosols shall not be distributed in a way that hides hazards, egress paths or warning signs, and a procedure must exist for prompt remedial action if obscuration becomes excessive. The Turkish regulation supplies the measurements. Article 73 requires directional signs to be white on a green background, to read ÇIKIŞ at normal exits and ACİL ÇIKIŞ at emergency exits, and to be at least 15 cm high. Maximum viewing distance is defined too: 100 times the sign height for externally or edge lit signs, and 200 times for internally lit ones. So a 15 cm internally lit sign is engineered for 30 metres. Heavy fog filling the room cuts that distance in practice. The same article puts signs between 200 and 240 cm above the floor and requires emergency wayfinding to run for at least 60 minutes, rising to 120 minutes where the occupant load is above 200. When you plan a fog heavy finale, the first thing to look at is not the stage but the exit door at the back of the room.
The invisible risk in CO2 jets and low fog
Carbon dioxide is colourless, odourless and heavier than air, so it collects under the stage, in the orchestra pit and in basement dressing rooms. Turkey sets a number for it. Annex 1 of the regulation on health and safety in work with chemical agents, the Kimyasal Maddelerle Çalışmalarda Sağlık ve Güvenlik Önlemleri Hakkında Yönetmelik published in the Resmî Gazete of 12 August 2013 (No. 28733), gives carbon dioxide an eight hour occupational exposure limit of 9000 mg/m3, equal to 5000 ppm. E1.23 covers the oxygen side, requiring oxygen levels to be monitored; its explanatory section cites OSHA for the point that levels should not fall below 19.5 percent, while anything above 23.5 percent counts as high and will accelerate a fire. Storage is a separate matter. Dry ice and liquid CO2 dewars should not be kept in confined spaces with poor ventilation, because the vessels vent pressure as they warm. Liquid synthetic air carries a separation risk as well: nitrogen boils at minus 196 and oxygen at minus 183 degrees, so the nitrogen vents first and depletes oxygen in the storage area. In practice: run jets in a ventilated area, secure the cylinders, keep bare hands off the hose end without cryogenic gloves, and clear the crew working under the stage before the cue.
Confetti, snow and foam: slips and cleanup
Residue creates two separate problems. The first is slipping, and the standard requires residue building up on walking surfaces to be monitored and controlled. Snow fluid and foam make a stage slick fast, so if there is choreography, dancing or anyone in heels, move the effect off the stage line or assign someone to wipe the deck during the break. Confetti works on different arithmetic. You decide the quantity, the venue is left with the cleaning, and most venues attach a cleaning surcharge to it while some ban it outright. If the contract does not say who pays for what, the invoice shows up at the end of the night. The second problem is contamination: the same standard asks for measures against fluid residue collecting on fire detection optics, stage lighting and projection equipment. A finale that fires confetti in front of an LED wall or a projector leaves you a maintenance list for the next morning. Spark and flame effects sit in another category altogether, since they count as pyrotechnic articles and require a certified operator.
What to put in writing to the venue and the supplier
Eight lines will do. The type of effect and the safety data sheet of the fluid. The venue's detection type: point optical, beam, aspirating or heat. The zones the effect will reach, and whether those zones send an automatic call to the fire brigade. Who performs the isolation if one is needed, and whose written approval covers it. Who holds the fire watch role while the effect runs. The test slot, and which mode the air handling will be in at that hour. Cleaning responsibility and any surcharge for confetti, snow and foam. For sparks or flame, the product category and the operator's certificate number. All of it is settled before load-in day, because nobody negotiates next to the alarm panel on show night. Treat this as a general framework; how a venue applies the fire regulation and how the local fire brigade works can differ, so confirm the detail with the venue's fire officer. Tales Event is based in İstanbul and produces gala nights, launches, dealer meetings and year-end parties with one team covering sound, lighting, staging, LED screens and stage effects. If you are planning an effect driven finale, send us the venue's detection type and we will build the test plan and the venue correspondence with you.
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