Aspirating Fire Detector Leak Detection via Pressure Threshold

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Solution Overview

Problem

Aspirating fire detection systems face challenges in effectively detecting leaks within their piping networks, which can reduce static air pressure and hinder fire detection, and leaks can also allow corrosive substances to damage internal components or escape into occupied areas.

Innovation Solution

A method and detector unit configuration that involves blocking airflow out of the detector unit, operating the aspirator at a predetermined power, measuring air pressure downstream, and determining leaks by comparing the measured pressure to a threshold, with options for automatic and periodic operation, and triggering alerts if leaks are detected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a flow meter is provided at the inlet of the central detector unit to detect leaks or blockages, then leak detection capability is improved, but device complexity increases

Engineering Contradiction:
Improveleak detection capabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The detector unit performs self-diagnosis by blocking its own outlet and measuring pressure buildup during aspirator operation to detect leaks in its internal airflow path, eliminating the need for external flow meters or separate leak detection devices

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The leak detection function is extracted from the external monitoring system and integrated directly into the detector unit's control system, allowing the same processor that controls aspirator operation to also analyze pressure data for leak detection

Inventive Principle:
Principle #2Taking out (Extraction)

2Measurement precision

If the outlet of the detector unit is blocked to measure pressure for leak detection, then measurement precision is improved, but loss of time increases due to operation interruption

Engineering Contradiction:
Improvepressure measurement accuracyVSAvoidoperation interruption time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The outlet blocking and pressure measurement process is implemented as a periodic self-test routine that operates at predetermined intervals, allowing the system to maintain normal detection functionality between tests while periodically verifying system integrity

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system performs preliminary checks by monitoring pressure during normal operation before fully blocking the outlet, allowing early detection of significant leaks that would prevent adequate pressure buildup, thus reducing the need for complete outlet blocking

Inventive Principle:
Principle #10Preliminary action

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 allows for reliable detection of leaks in the airflow path, ensuring accurate sampling and preventing damage from corrosive substances, while enabling the system to resume normal operation if no leaks are found, thus maintaining effective fire detection and safety.

Implementation Method 1

Air is drawn in through the sampling holes and along the pipes by means of an aspirator within a central detector unit

Methodology Applied
Scientific EffectPressure difference: Pressure Gradient

Implementation Method 2

measuring an air pressure downstream of the aspirator; The measured pressure may comprise a differential pressure. The differential pressure may be a differential pressure between a pressure upstream of the aspirator and a pressure downstream of the aspirator

Methodology Applied
Scientific EffectPressure differential measurement: Pressure Gradient

Data Source

PatentEP3907484B1Detection of leakage in an aspirating fire detection system
Publication Date: 2023.08.30 CARRIER CORP
  • EP3907484B1 patent drawingFigure 1~2

AI summary

A method of detecting leakage from a central detector unit 2 of an aspirating fire detection system 1 is described. The method comprises actuating a valve 8 to block an outlet 8 of the detector unit 2, operating an aspirator 6 of the detector unit 2 at maximum power, and measuring a differential air pressure across the aspirator 6. If the resulting measured air pressure is below a predetermined threshold, it can be inferred that there is a leak within the central detector unit 2 downstream of the aspirator 6.