Detection
CO₂ Alarms & Carbon Dioxide Detectors
Carbon dioxide is colourless, odourless and heavier than air. In cellars and dispense rooms a leaking CO₂ cylinder or bulk tank can displace oxygen at floor level within minutes.
- Low-level sensor siting — CO₂ pools at floor level
- Alarms typically at 1.5% and 3% by volume
- Internal and external sounder beacons at cellar access
Where CO₂ alarms are needed
- Beer cellars with CO₂ or mixed-gas cylinders and bulk tanks
- Dispense and syrup rooms behind bars
- Basement stores and confined plant spaces with CO₂ lines
- Restaurants with in-house carbonation systems
Alarm levels and outputs
| Level | Typical threshold | Response |
|---|---|---|
| Pre-alarm | 1.5% CO₂ | Internal sounder, ventilation boost |
| High alarm | 3% CO₂ | Do not enter beacon outside the door, evacuate |
| Fault | Sensor or wiring | Panel fault relay |
Servicing
NDIR CO₂ sensors are stable but still need annual gas-applied calibration and a functional sounder test. Cellar hatches, cylinder changes and drainage layouts all affect detector position — re-survey after any cellar refit.
Frequently asked questions
Is a CO₂ alarm a legal requirement in a cellar?
Employers have duties under COSHH and the Confined Spaces Regulations. Where CO₂ is stored or used in a poorly ventilated space, a fixed alarm is the standard control measure.
Is CO₂ the same as carbon monoxide?
No. CO₂ is an asphyxiant from stored gas or fermentation; CO is a toxic product of incomplete combustion and needs a separate detector.
Related guides
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Ambient air quality monitoring in kitchens and restaurants.
Carbon Monoxide Detection
Fixed CO monitors for boiler and plant rooms.
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Air pressure switches, airflow sensors, current monitors, e-stops.
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Ventilation interlock, airflow proving and CP42 compliance.
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