Aspirating Fire Detector False Alarm Reduction
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Solution Overview
Problem
Aspirating fire detector systems face false fault detections due to sudden changes in pressure, which can alter air flow beyond predetermined thresholds, leading to incorrect indications of blockages or interruptions in the conduits.
Innovation Solution
The method involves using a pressure sensor to detect sudden changes in pressure and implementing corrective measures, such as adjusting the ventilator's operating parameters or applying a correction factor to the air flow signal, to prevent false fault detections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the predetermined threshold for fault detection is set at ±20% air flow deviation, then actual faults can be detected reliably, but false fault detections occur due to sudden pressure changes
Solution Approach 1:
A pressure sensor is introduced as an intermediary device to detect sudden pressure changes in the aspirated air. The pressure sensor provides additional information about environmental conditions that affect air flow, allowing the system to distinguish between flow changes caused by pressure variations and those caused by actual conduit faults. This intermediary measurement enables correction of the air flow signal to prevent false fault detections while maintaining reliable fault detection.
Solution Approach 2:
The system implements feedback by continuously monitoring pressure changes and using this information to adjust the interpretation of air flow measurements. When the pressure sensor detects a sudden pressure change, the system feeds back this information to modify the fault detection logic, preventing false alarms. The feedback loop allows the system to adapt to environmental conditions while maintaining compliance with the ±20% threshold for actual fault detection.
2Object-affected harmful factors
If the predetermined threshold is increased beyond ±20% to avoid false detections, then false fault detections are reduced, but actual faults may not be detected and regulatory compliance is lost
Solution Approach 1:
The pressure sensor serves as an intermediary that provides contextual information about environmental conditions. By measuring pressure independently, the system can differentiate between air flow changes caused by pressure variations (not faults) and those caused by actual conduit blockages or interruptions (true faults). This allows maintenance of the strict ±20% threshold for fault detection while avoiding false detections.
Solution Approach 2:
The system changes the parameter being monitored by adding pressure measurement to the existing air flow measurement. Instead of relying solely on air flow threshold comparisons, the system now considers both air flow and pressure parameters. When pressure changes are detected, the system adjusts its fault detection criteria accordingly, allowing it to maintain high sensitivity to actual faults while being robust against false detections from pressure variations.
3Object-affected harmful factors
If pressure compensation is implemented using a pressure sensor, then false fault detections are avoided, but device complexity increases
Solution Approach 1:
A pressure sensor is added as a relatively simple intermediary device to detect pressure changes. The sensor provides pressure data that is used to modulate or correct the air flow signal processing logic. This addition of a single sensor and associated processing represents a modest increase in complexity that yields significant benefits in reducing false fault detections while maintaining regulatory compliance.
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 approach effectively avoids false fault detections caused by sudden pressure changes, ensuring the aspirating fire detector system operates reliably and complies with regulations like EN 54-20.
Implementation Method 1
a pressure sensor configured to detect the pressure of air that is drawn through the inlet and into the fire detector
Implementation Method 2
a flow meter configured to measure the flow of air drawn through the inlet and to the fire detector
Implementation Method 3
a ventilator configured to draw air through the inlet of the conduit and into the fire detector
Data Source
AI summary
A method of operating an aspirating fire detector system (3) including a fire detector (19), a conduit (7) having an inlet and being connected to the fire detector (19), a ventilator (15) configured to draw air through the inlet of the conduit (7) and into the fire detector (19), a pressure sensor (13) configured to sense the pressure of air being that is drawn through the inlet and into the fire detector (19), and a flow meter (17) configured to measure the flow of the air drawn through the inlet and to the fire detector (19).