Energy-Limiting Barrier for Flameproof Hazardous Area Control

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Solution Overview

Problem

Existing process control systems in hazardous environments face challenges with stringent flameproof housing requirements and high costs associated with intrinsically safe barriers, limiting the implementation of convenient features like LCD displays and switches, and making it difficult to access and test emergency shutdown valves.

Innovation Solution

A flameproof apparatus with an energy-limiting barrier that allows for safe operation without complete flameproof enclosures, enabling the use of non-ignition-capable voltage outputs and user interface components in hazardous environments, and a dual power source local control panel for emergency shutdown valves that can be installed using flameproof methods.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If flameproof housing requirements are implemented, then safety in hazardous environments is ensured, but device complexity and cost increase significantly

Engineering Contradiction:

ImprovesafetyVSAvoidhousing requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system is divided into two functional segments: a flameproof housing containing only the energy-limiting barrier and essential components, and a separate non-flameproof housing containing user interface components (LCD displays, buttons, switches). This segmentation allows each housing to have optimized requirements - the flameproof housing ensures safety while the non-flameproof housing provides easy access to controls and displays.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An energy-limiting barrier acts as an intermediary component between the hazardous environment and the non-flameproof user interface. This barrier limits the energy of electrical circuits to levels that cannot cause ignition, thereby mediating the safety requirements and allowing non-flameproof components to be used in hazardous areas.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If intrinsically safe barriers are used, then energy limitation is achieved, but cost and installation complexity increase

Engineering Contradiction:

Improveenergy limitationVSAvoidinstallation cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The energy-limiting barrier functionality is merged with the flameproof housing structure, eliminating the need for separate intrinsically safe barriers. The housing itself is designed to provide the energy limitation through its internal circuitry and component selection, reducing overall system cost and installation complexity.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The system provides its own energy limitation function through integrated circuitry within the flameproof housing, rather than requiring external intrinsically safe barriers. The housing self-regulates energy levels to prevent ignition, making the system self-sufficient and reducing dependency on additional safety components.

Inventive Principle:

Principle #25Self-service

3Reliability

If complete flameproof enclosures are used, then safety is maintained, but access to controls and displays becomes difficult

Engineering Contradiction:

ImprovesafetyVSAvoidaccess to controls

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

4Reliability

If earth ground is provided for intrinsically safe barriers, then energy limitation to earth is achieved, but installation convenience decreases and costs increase

Engineering Contradiction:

Improveenergy limitation to earthVSAvoidinstallation convenience

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP1982397B1Flameproof apparatus using non-grounded energy-limiting barrier

Publication Date: 2019.07.10 FISHER CONTROLS INT LLC

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AI summary

A device intended to meet flameproof approval requirements is configured to have two compartments separated by an energy-limiting barrier. The first compartment of the device houses the wiring terminations that bear ignition- capable energy and, therefore, must be flameproof. The energy-limiting barrier is configured to limit the energy that can reach the second compartment to a level that is not ignition capable. This allows the second compartment to be safe without meeting the flameproof requirements, and allows user-interface elements such as switches and indicators to be designed in a more cost-effective manner.