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Know Your Detector Type
Fog and haze can activate smoke detectors because their airborne particles may resemble the products of combustion that the detectors are designed to identify. Understanding the system installed in your space is the first step toward minimizing unwanted alarms.
Four common detector types are:
• Ionization detectors: These maintain a small electrical current inside a sensing chamber. Particles entering the chamber can disrupt the current and activate the alarm.
• Photoelectric detectors: These use a light source and sensor. When airborne particles enter the detector, they can scatter light onto the sensor and trigger an alarm.
• Combination detectors: These incorporate both ionization and photoelectric technology. They can be highly sensitive because they are designed to identify multiple types of fire.
• Heat detectors: These respond to a specified temperature or a rapid change in temperature rather than airborne particles.
Detectors may also be connected to a larger fire-alarm or suppression system. Activation could initiate building alarms, notify monitoring services or summon emergency responders. Confirm the system type and response sequence with the venue before introducing atmospheric effects.
Match the Effect to the Space
Begin by defining the effect and evaluating the room. Do you need an instantaneous blast, a slow stream of fog or a continuous haze? Consider the size of the space, ceiling height, detector locations and airflow.
Machine output and fluid selection both matter. A high-output machine can quickly introduce a large concentration of particles, while fluid density and hang time determine how long those particles remain airborne.
For example:
• An Atlas paired with Cryo Burst fluid can produce a high-intensity blast that dissipates in approximately five seconds.
• Apex provides a quick-dissipating effect with a hang time of roughly 30 seconds.
• A Prodigy or Prodigy Plus with Presto fluid can create horizontal fog that dissipates in approximately 20 seconds as it moves across the stage.
These are starting points, not guarantees. Room conditions and detector sensitivity will affect the outcome.
Consider Placement and Airflow
Identify the location of every detector and observe how air travels through the room. HVAC supply vents, return ducts, fans and open doors can carry atmospheric effects in unexpected directions.
Place the machine so the fog has enough time and distance to dissipate before reaching a detector. Because warm fog tends to rise, a horizontal effect placed below ceiling-mounted detectors may provide more control than aiming output upward. Low-lying fog can also reduce upward travel, although air movement can still lift or redirect it.
Run tests under the same HVAC and ventilation conditions expected during the event. A test performed with the air system off may not represent what happens during the show.
Approach Haze Carefully
Haze presents a greater challenge because it is designed to spread evenly and remain suspended, making lighting and lasers more visible without producing an opaque cloud. That same persistence increases the chance that particles will reach a detector.
Venue Coordination & Testing Thresholds:
• Coordinate with a maintenance manager or Fire Marshal to temporarily disable the alarm audio/response system while keeping detector monitoring active.
• Test different haze and fan output settings to determine the maximum safe threshold before triggering a sensor.
Keep in mind that density, particle size, humidity, room airflow and detector sensitivity can all change the result.
