Aspirated Smoke Detector Airflow Divider
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Solution Overview
Problem
Aspirated smoke detectors face challenges in avoiding pollution of the detection chamber and associated filters due to dust and other airborne pollutants, which can lead to errors in smoke detection.
Innovation Solution
The implementation of an airflow divider and virtual impactor system that separates particles into two groups, using inertia to direct larger particles away from the detection chamber, allowing only a smaller sample of air to enter, which reduces contamination and minimizes filter pollution. This system utilizes separate scattering volumes for measuring particle concentrations, with backward scattering for larger particles and forward scattering for smaller particles, and calibrates amplifiers to distinguish between dust and smoke.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fan or blower draws ambient air through the detection chamber, then smoke particles can be detected, but dust and airborne pollutants contaminate the chamber and filters
Solution Approach 1:
The air stream is segmented into two paths: a first path directing larger particles away from the chamber, and a second path directing a smaller sample of air through the chamber for detection. This segmentation separates harmful large particles from useful small smoke particles.
Solution Approach 2:
The invention extracts only a smaller sample of air (second path) from the total air stream for chamber analysis, while removing larger particles through the first path. This extraction reduces the amount of contaminating air entering the chamber while still capturing smoke particles.
2Object-affected harmful factors
If filters are used to remove dust, then chamber cleanliness is improved, but filters become polluted and require maintenance
Solution Approach 1:
The airflow divider performs preliminary separation of particles before air enters the chamber or reaches filters. By directing larger particles away in the first path before chamber entry, the system prevents contamination in advance, extending filter and chamber service life.
3Measurement precision
If the entire air stream is analyzed, then comprehensive particle detection is achieved, but larger particles cause detection errors
Solution Approach 1:
The invention applies different quality treatment to different particle sizes within the air stream. Larger particles are directed away through the first path, while a controlled sample for detection is taken through the second path. This local quality differentiation ensures that only appropriate particles are analyzed for smoke detection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution extends the service life of the detector by keeping the chamber clean, reducing errors, and minimizing filter pollution, ensuring accurate smoke detection by isolating larger particles and focusing on smaller smoke particles.
Implementation Method 1
separates particles into two groups using inertia to direct larger particles away from the detection chamber
Implementation Method 2
backward scattering for larger particles and forward scattering for smaller particles
Implementation Method 3
backward scattering for larger particles and forward scattering for smaller particles
Data Source
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AI summary
An aspirated smoke detector includes an ambient air flow separation element in combination with a smoke sensing chamber. The flow separation element can be an active or a passive element. Separated ambient, carrying relative small particles can flow into the sensing chamber. Ambient carrying relatively larger particulate matter is excluded from the sensing chamber.