Aspirating detector false alarms are rare in a well-designed system, but when they happen they are costly. People leave the building, the fire brigade may be called and trust in the system drops.
In this guide, we list the common causes, show how to find the real one and explain what to change. Good news first: most false alarms come from a small number of causes that you can fix.
Why do aspirating detector false alarms happen?
An aspirating detector is very sensitive, so it can react to anything that looks like smoke. The cause is usually in the environment, in the settings or in the pipes, not in the detector itself.
Modern detectors reduce the problem. For example, ClassiFire intelligence in the ModuLaser and MiniLaser learns the normal conditions of the room and separates smoke from dust. Even so, the design must fit the room.
The most common causes
Most cases fit into the table below.
| Cause | Det du ser | Fix |
|---|---|---|
| Dust and dirt | Rising background level, alarms after cleaning or work | Change the filter and check the alarm levels |
| Building work | Alarms during drilling, cutting or welding | Isolate the zone during work and cover the sampling holes |
| Steam, fumes or exhaust | Alarms near kitchens, loading bays or engines | Move the holes or adjust the delay and levels |
| Airflow changes | Alarms when air handling starts | Review hole positions against the airflow |
| Sensitivity too high | Frequent early alarms in a dirty site | Choose the right class and alarm levels for the room |
| Leaking pipe | Airflow faults and odd readings | Seal the joints and repeat the test |
How to find the cause of aspirating detector false alarms
Work in a clear order, and change only one thing at a time.
- Read the event log to see when each alarm happened and at which level.
- Look for a pattern: the time of day, a machine starting or a cleaning round.
- Check the airflow and the filter.
- Inspect the sampling holes and pipes in the area that reported the alarm.
- Compare the alarm levels with the risk of the room.
How to prevent false alarms
Prevention starts at design. Also, place sampling holes away from direct exhaust and supply air. In addition, set alarm levels that fit the room. A clean data hall can use a much higher sensitivity than a dusty workshop. Our guide on aspirating smoke detector sensitivity explains the levels.
Finally, keep up the maintenance, because a clean filter keeps the readings steady.
Products that help
The ModuLaser and MiniLaser both use ClassiFire intelligence and four alarm levels for reliable early warning. Also, AirSense detectors are built to tell smoke from dust in dirty, cold or humid sites. See AirSense for details.
Nøkkeltakeaways
- Most false alarms come from dust, work on site, fumes, airflow or settings.
- Read the event log first and look for a pattern before you change anything.
- Match the alarm levels to the room instead of just lowering sensitivity.
- ClassiFire intelligence in ModuLaser and MiniLaser separates smoke from dust.
Vanlige spørsmål
Why does my aspirating smoke detector give false alarms?
The usual causes are dust, building work, steam or fumes, airflow changes or a sensitivity that is too high for the room.
Can a dirty filter cause a false alarm?
A dirty filter mainly lowers the airflow and raises faults. It can also change the readings, so replace it when the manual says so.
Should I just lower the sensitivity?
Not as a first step. Find the cause first, then adjust the alarm levels so they still protect the risk.
Do aspirating detectors give more false alarms than point detectors?
No, not when they are well designed. Features such as ClassiFire learn the normal conditions and ignore background dust.
Start with the basics in how an aspirating smoke detector works, or see the aspirating smoke detection systems.