RFUnderstanding Obscuration in Smoke Detectors
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This article explains the definition of obscuration and its importance in smoke detection.
What is Obscuration?
The term “obscuration” is a unit of measurement used to define the sensitivity of a smoke detector. Essentially, it quantifies how much smoke is required to trigger an alarm.
Obscuration Definition: It is a measurement unit that describes the sensitivity of smoke detectors.
Here’s how obscuration relates to smoke concentration and visibility:
- Higher obscuration value: Indicates higher smoke concentration levels and lower visibility. More smoke is needed to trigger the alarm.
- Lower obscuration value: Indicates lower smoke concentration levels and higher visibility. Less smoke is needed to trigger the alarm.
Obscuration is typically measured in obs/m (obscuration per meter) or obs/ft (obscuration per foot).
Different Smoke Detectors, Different Obscuration Ratings
Different types of smoke detectors have varying obscuration specifications. It’s crucial to select the appropriate smoke detector for a specific application based on factors like the area to be protected and its sensitivity requirements.
The following table outlines the obscuration ratings of commonly used smoke detectors:
| Smoke detector type | Obscuration rating |
|---|---|
| Photoelectric smoke detector | 2% obs/ft to 4% obs/ft |
| Ionization Smoke detector | 0.8% obs/ft to 1.5% obs/ft |
| Laser based Smoke detector | 0.02% obs/ft to 2% obs/ft |
| Aspiration Smoke detector | 0.0015% obs/ft to 6.25% obs/ft |
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