## Common ground
All options are devices designed to detect gas or smoke, commonly used for safety and early warning.
## Options at a glance
**8531.10 – Integrated alarm**
- **Defining trait:** Emits an audible or visual alarm directly from the device, like a standard fire alarm.
- **Typical examples:** Home smoke detectors with beeping alarms, carbon monoxide detectors that chirp when levels rise.
- **Best fit when:** The device’s primary purpose is to alert occupants immediately on detection.
**9027.10 – Analytical detection**
- **Defining trait:** Performs chemical or physical analysis of gas/smoke (e.g., measures concentration, identifies type).
- **Typical examples:** Industrial gas analyzers, lab-grade smoke composition sensors.
- **Best fit when:** The device provides detailed data beyond simple detection (e.g., “CO level: 50 ppm”).
**9027.50 – Optical radiation-based**
- **Defining trait:** Uses UV, visible, or infrared light to detect particles or gas via scattering, absorption, or fluorescence.
- **Typical examples:** Laser-based smoke detectors, infrared gas sensors in industrial settings.
- **Best fit when:** The detection method relies on optical sensing (e.g., beam interruption or spectral analysis).
## Key differences
| Feature | 8531.10 (Alarm) | 9027.10 (Analysis) | 9027.50 (Optical) |
|-----------------------|-----------------|--------------------|-------------------|
| Alarm output | Yes | No (usually) | Optional |
| Measures concentration| No | Yes | Indirectly |
| Detection method | General | Chemical/physical | Light-based |
## How to choose
- Does it sound an alarm directly? → 8531.10
- Does it identify or measure gas/smoke type/concentration? → 9027.10
- Does it use UV, visible, or IR light to detect particles/gas? → 9027.50
## Overlaps & pitfalls
- A device can combine multiple traits (e.g., optical sensor with alarm → fits both 8531.10 and 9027.50).
- If a detector analyzes gas *and* alarms, prioritize the **main function**: alarm for safety devices, analysis for scientific/industrial use.
- “Optical” does not imply alarm — some optical detectors only send signals without sound.
- No priority rule is implied; choose based on the product’s defining feature