Intrinsically Safe Laser Spectrometer Design

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Solution Overview

Problem

Spectroscopy-based analyzers face challenges in ensuring safety in hazardous locations due to the need for expensive and bulky explosion-proof enclosures, which are costly and burdensome for certifications like CSA Division 1 and ATEX Zone 1, and existing solutions do not provide effective intrinsically safe configurations.

Innovation Solution

The implementation of intrinsically safe designs for spectroscopy-based analyzers, which limit optical, electrical, and thermal ignition-causing parameters in hazardous areas to prevent ignition, using components like clamping zener diodes, fuses, and active power limiting circuits, and employing fiber optics to reduce the need for electrical connectors and enclosures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If explosion-proof enclosures are used to ensure safety in hazardous locations, then safety is improved, but device weight and cost increase significantly

Engineering Contradiction:
ImprovesafetyVSAvoidenclosure weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent replaces the mechanical explosion-proof enclosure system with an intrinsically safe electrical and optical design. By limiting electrical power and optical output to levels that cannot cause ignition, the system eliminates the need for heavy mechanical protection structures, thereby reducing weight while maintaining safety in hazardous locations.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the operating parameters of electrical and optical components to intrinsically safe levels. By controlling voltage, current, and optical output power within specific limits that cannot ignite explosive atmospheres, the system achieves safety without requiring explosion-proof enclosures, thus reducing weight and cost.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If explosion-proof enclosures are used to ensure safety in hazardous locations, then safety is improved, but manufacturing cost increases significantly

Engineering Contradiction:
ImprovesafetyVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces the expensive mechanical explosion-proof enclosure system with intrinsically safe electrical and optical design. This substitution eliminates complex manufacturing requirements for heavy-duty enclosures, reducing manufacturing cost while maintaining safety through controlled power and optical output levels.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes operational parameters to intrinsically safe levels, which simplifies the manufacturing process. Instead of requiring expensive explosion-proof certified enclosures, the system achieves safety through controlled electrical and optical parameters, reducing manufacturing complexity and cost.

Inventive Principle:
Principle #35Parameter changes

3Ease of operation

If conventional electrical connectors and enclosures are used, then component connection is simplified, but safety in hazardous locations is compromised

Engineering Contradiction:
Improvecomponent connectionVSAvoidhazardous location safety
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent replaces conventional electrical connectors with fiber optic connections for signal transmission. Fiber optics eliminate electrical sparks and overheating risks, providing inherent safety in hazardous locations while maintaining ease of connection through standard fiber optic interfaces.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces fiber optic cables as an intermediary between electrical components and the hazardous environment. The fiber optic medium transmits signals without conducting electricity into the hazardous area, eliminating ignition risks while maintaining communication and control functionality.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Measurement precision

If high optical power is used for spectroscopic analysis, then measurement precision is improved, but ignition risk in hazardous atmospheres increases

Engineering Contradiction:
Improvespectroscopic analysis precisionVSAvoidignition risk
Core Design Contradiction:
Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent changes the optical power parameter to intrinsically safe levels that cannot cause ignition in explosive atmospheres. By operating the laser at reduced power levels within certified intrinsically safe limits, the system maintains sufficient precision for spectroscopic analysis while eliminating the ignition hazard associated with high optical power.

Inventive Principle:
Principle #35Parameter changes

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 reduces the need for heavy, expensive enclosures, simplifies certification processes, and enhances safety and applicability worldwide by maintaining components below incendiary levels and limiting power to prevent ignition, thereby reducing certification costs and enclosure size.

Implementation Method 1

employing fiber optics to reduce the need for electrical connectors and enclosures

Methodology Applied
Scientific EffectOptical fiber transmission: Optical Fibre

Implementation Method 2

using components like clamping zener diodes, fuses, and active power limiting circuits

Methodology Applied
Scientific EffectZener diode voltage clamping: Diode

Implementation Method 3

using components like clamping zener diodes, fuses, and active power limiting circuits

Methodology Applied
Scientific EffectFuse protection:

Implementation Method 4

providing optical power from a laser to a volume of the mixture

Methodology Applied
Scientific EffectLaser emission: Laser

Implementation Method 5

based on the principle of tunable diode laser spectroscopy which is measuring oxygen in potentially explosive atmospheres

Methodology Applied
Scientific EffectTunable diode laser spectroscopy:

Data Source

PatentEP3268723B1Intrinsically safe spectroscopic analyzer
Publication Date: 2023.01.25 ENDRESSHAUSER OPTICAL ANALYSIS INC
  • EP3268723B1 patent drawingFigure 1
  • EP3268723B1 patent drawingFigure 2
  • EP3268723B1 patent drawingFigure 3

AI summary

A laser spectrometer can be operated for analysis of one or more analytes present in a combustible gas mixture. The spectrometer can include one or more features that enable intrinsically safe operation. In other words, electrical, electronic, thermal, and/or optical energy sources can be limited within an hazardous area of the spectrometer where it is possible for an explosive gas mixture to exist.