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Introduction

Gas analysis is an essential part of many industrial processes, including oil and gas production, refineries, petrochemical manufacturing, chemical processing, hydrogen production and pharmaceutical manufacturing.

However, selecting a Gas Analyzer for a hazardous area requires considerably more attention than selecting a conventional analyzer for a safe-area installation.

Industrial plants may contain flammable gases, vapours or dust that can create potentially explosive atmospheres. In such environments, the analyzer and associated equipment must be selected according to the site's hazardous-area classification and applicable safety requirements.

A suitable Industrial Gas Analyzer must therefore satisfy two fundamental requirements:

1. It must provide reliable and accurate gas measurement.

2. Its construction and installation must be appropriate for the hazardous environment.

This article explains the important considerations when selecting Gas Analyzers for Hazardous Areas, including analytical technology, hazardous-area classification, certification, sample conditioning, installation and lifecycle cost.

What Is a Gas Analyzer?

A Gas Analyzer is an analytical instrument designed to measure the concentration of one or more components in a gas stream.

Depending on the application, a gas analyzer can measure:

• Oxygen (O₂)

• Hydrogen (H₂)

• Carbon monoxide (CO)

• Carbon dioxide (CO₂)

• Methane (CH₄)

• Sulfur dioxide (SO₂)

• Nitrogen oxides (NOx)

• Hydrogen sulfide (H₂S)

• Ammonia (NH₃)

• Moisture

• Hydrocarbons

• Other process gases

Gas analyzers can be used for:

• Process monitoring

• Combustion optimization

• Safety monitoring

• Product quality control

• Hydrogen purity monitoring

• Environmental monitoring

• CEMS

• Process control

For hazardous-area applications, the analyzer technology must be evaluated together with the protection method and installation environment.

Why Are Hazardous-Area Gas Analyzers Different?

A conventional laboratory or safe-area analyzer may not be suitable for installation in an area where flammable gas or vapour can be present.

Potential ignition sources in electrical equipment include:

• Sparks

• Electrical arcs

• Hot surfaces

• Static discharge

• Excessive electrical energy

Hazardous-area equipment is designed and certified according to applicable explosion-protection requirements to reduce the possibility of ignition.

Therefore, selecting a hazardous-area Gas Analyzer involves both:

Analytical performance + Explosion protection

What Is a Hazardous Area?

A hazardous area is a location where a potentially explosive atmosphere may be present.

An explosive atmosphere can occur when a flammable gas, vapour or dust mixes with air within an appropriate concentration range and an ignition source is present.

Industries where hazardous areas can occur include:

• Oil and gas

• Refineries

• Petrochemical

• Chemical

• Hydrogen

• Pharmaceutical

• Natural gas processing

• Solvent manufacturing

• Fuel storage and handling

The hazardous-area classification should normally be determined by the plant's engineering and safety teams.

Hazardous Area Zones for Gas and Vapours

For gases and vapours, hazardous areas are commonly classified using zones.

Zone 0

An explosive gas atmosphere is present continuously, for long periods or frequently.

Zone 1

An explosive gas atmosphere is likely to occur occasionally during normal operation.

Zone 2

An explosive gas atmosphere is not likely to occur during normal operation, but if it does occur, it is expected to exist only for a short period.

The analyzer must be appropriate for the actual zone in which it will be installed.

Gas Analyzer Technologies for Hazardous Areas

Different analytical technologies can be used for industrial gas measurement.

The appropriate technology depends on the gas being measured, concentration range, process conditions and required performance.

NDIR Gas Analyzer

NDIR, or Non-Dispersive Infrared analysis, measures infrared absorption by gases.

It is commonly used for gases such as:

• CO

• CO₂

• CH₄

• Other infrared-active gases

NDIR analyzers can be suitable for industrial process applications when the analyzer configuration and installation meet the applicable hazardous-area requirements.

Paramagnetic Oxygen Analyzer

Paramagnetic analyzers use the magnetic properties of oxygen to determine its concentration.

They are used for oxygen measurement in applications such as:

• Combustion monitoring

• Process control

• Industrial gas analysis

The specific analyzer configuration must be checked for hazardous-area suitability.

Electrochemical Gas Analyzer

Electrochemical sensors detect gases through an electrochemical reaction.

They can be used for gases such as:

• O₂

• CO

• H₂S

• Other gases depending on sensor design

Sensor life, cross-sensitivity and environmental conditions should be evaluated carefully.

Thermal Conductivity Analyzer

Thermal conductivity analyzers determine gas concentration based on differences in thermal conductivity.

They can be useful for:

• Hydrogen analysis

• Binary gas mixtures

• Process gas monitoring

Hydrogen applications require particular attention to hazardous-area classification and equipment suitability.

Zirconia Oxygen Analyzer

Zirconia technology is widely used for oxygen measurement, particularly in combustion applications.

Typical applications include:

• Boilers

• Furnaces

• Heaters

• Kilns

• Process combustion

The installation arrangement and analyzer configuration must be suitable for the process environment.

TDL Gas Analyzer

Tunable Diode Laser (TDL) analyzers use laser absorption spectroscopy to measure selected gases.

Applications can include measurement of:

• H₂O

• NH₃

• O₂

• CO

• Other gases depending on the laser wavelength

TDL systems can offer highly selective measurements for demanding process applications.

Gas Chromatograph

Gas chromatographs separate gas components before detection.

Process GC systems are commonly used in:

• Refineries

• Petrochemical plants

• Natural gas processing

• Hydrogen systems

• Chemical plants

For hazardous-area installations, the specific GC configuration and associated equipment must meet the required installation classification.

Gas Analyzer Working Principle

The Gas Analyzer Working Principle varies according to the analytical technology.

For example:

• NDIR analyzers measure infrared absorption.

• Paramagnetic analyzers measure oxygen's magnetic properties.

• Electrochemical analyzers measure an electrochemical response.

• Thermal conductivity analyzers measure differences in thermal conductivity.

• TDL analyzers measure laser absorption.

• Gas chromatographs separate and detect individual components.

The analytical principle should be selected according to:

• Target gas

• Concentration

• Gas matrix

• Accuracy

• Detection limit

• Response time

• Process conditions

The hazardous-area certification is a separate consideration from the analytical measurement principle.

ATEX and Gas Analyzers

ATEX is a European framework concerning equipment and protective systems intended for use in potentially explosive atmospheres.

Where applicable, ATEX-certified equipment provides a conformity route for equipment intended for hazardous environments within its specified conditions.

When purchasing an ATEX Gas Analyzer, the purchaser should review the actual equipment marking and certification documentation rather than simply relying on a statement such as "ATEX compliant."

IECEx and Hazardous-Area Gas Analyzers

IECEx is an international certification system associated with equipment used in explosive atmospheres.

Depending on the project and location, customers may specify:

• ATEX

• IECEx

• Both

• National or project-specific requirements

The required certification should be confirmed with the plant owner, consultant or engineering contractor before equipment selection.

Gas Groups

Gas groups are another important consideration.

Hazardous-area equipment may be classified for different gas groups, commonly including:

• IIA

• IIB

• IIC

The gas group relates to the characteristics of the explosive atmosphere.

Hydrogen, for example, presents demanding explosion-protection requirements and must be considered carefully when specifying equipment.

The actual hazardous-area documentation for the site should determine the required gas group.

Temperature Classes

The temperature class indicates the maximum surface temperature of equipment under specified conditions.

Common temperature classes include:

• T1

• T2

• T3

• T4

• T5

• T6

The required temperature class depends on the ignition characteristics of the gases or vapours present.

A Gas Analyzer installed in a hazardous area must have an appropriate temperature classification for the application.

Explosion Protection Methods

Different explosion-protection concepts may be used depending on the analyzer and installation.

These can include:

Intrinsic Safety

The electrical energy in the circuit is limited to prevent ignition under specified conditions.

Flameproof/Explosion-Proof Construction

The equipment is designed to contain an internal explosion and prevent flame propagation to the surrounding atmosphere.

Pressurization or Purging

A protective gas or controlled pressure can be used to prevent the hazardous atmosphere from entering a protected enclosure.

The appropriate protection concept depends on the equipment design and hazardous-area classification.

In-Situ vs Extractive Gas Analysis

Hazardous-area installations can use either in-situ or extractive analysis.

In-Situ Analysis

The analyzer or sensor is installed directly at or near the process measurement point.

Advantages can include:

• Fast response

• Short measurement path

• Reduced sample transport delay

However, the analyzer is exposed more directly to process and environmental conditions.

Extractive Analysis

A sample is extracted from the process and transported to the analyzer.

A typical system is:

Process → Sampling Probe → Sample Conditioning → Gas Analyzer

The analyzer may be installed in a safe area, while the sampling equipment is located at the process.

This arrangement can simplify maintenance in some applications, but the complete sample system must still be engineered correctly.

Sample Conditioning for Hazardous Areas

Sample conditioning is a critical component of many industrial gas-analysis systems.

Depending on the application, the system may include:

• Sampling probe

• Filters

• Heated sample lines

• Gas cooler

• Condensate separator

• Pressure regulator

• Sample pump

• Flow controller

• Calibration valves

The sample-conditioning system must be designed for:

• Gas composition

• Temperature

• Pressure

• Moisture

• Dust

• Corrosive gases

• Hazardous-area classification

A high-quality analyzer cannot compensate for an incorrectly designed sampling system.

Hazardous-Area Gas Analyzer Applications

Oil & Gas

Gas analyzers may be used for:

• Hydrocarbon analysis

• H₂S monitoring

• O₂ measurement

• Moisture analysis

• Process optimization

Hazardous-area requirements are especially important around hydrocarbon-handling equipment.

Refineries

Refineries use gas analysis throughout various process units.

Applications include:

• Refinery gas analysis

• Hydrogen purity

• Combustion monitoring

• Process control

• Flue-gas monitoring

Petrochemical Plants

Petrochemical processes can involve flammable gases and vapours.

Gas analyzers may monitor:

• Hydrocarbons

• H₂

• CO

• CO₂

• O₂

• Moisture

Chemical Plants

Chemical manufacturing can involve combustible gases and solvent vapours.

Gas analysis can support:

• Process control

• Product quality

• Safety

• Emission monitoring

Hydrogen Plants

Hydrogen production and handling require careful equipment selection.

Applications can include:

• Hydrogen purity

• Oxygen contamination

• Nitrogen contamination

• Moisture

• Electrolyzer monitoring

• Compressor outlet monitoring

Where analyzers are installed in hazardous areas, the required equipment protection must be established from the site classification.

Pharmaceutical Plants

Certain pharmaceutical processes involve flammable solvents.

Gas analysis may be used for:

• Oxygen monitoring

• Solvent vapour monitoring

• Process gases

• Inerting systems

Gas Analyzer Installation in Hazardous Areas

Installation should follow the manufacturer's certified installation instructions and the requirements applicable to the site.

Important considerations include:

• Correct mounting

• Certified cable glands

• Proper grounding

• Appropriate barriers/isolators where required

• Correct electrical connections

• Suitable enclosure

• Environmental protection

• Correct sample-system installation

Only qualified personnel should install and maintain equipment in hazardous areas.

Importance of Certification Documentation

Before purchasing a hazardous-area Industrial Gas Analyzer, request relevant documentation.

Depending on the equipment and project, this can include:

• Declaration of conformity

• ATEX documentation

• IECEx documentation

• Product certificate

• Equipment marking

• Technical datasheet

• Installation manual

• Safety instructions

• Certified accessory information

The documents should be checked against the actual analyzer model and configuration being offered.

Gas Analyzer Price in India

The Gas Analyzer Price in India varies significantly depending on the application and analyzer configuration.

Factors affecting the price include:

• Analytical technology

• Number of gases

• Measurement range

• Accuracy

• Detection limit

• Hazardous-area certification

• Enclosure

• Sample-conditioning system

• Sampling probe

• Heated sample line

• Gas cooler

• Calibration system

• Communication

• Data acquisition

• Installation

• Commissioning

• Service support

A hazardous-area analyzer may cost more than an equivalent safe-area analyzer because of additional explosion-protection design, certification and specialized components.

Therefore, quotations should be compared on a complete technical configuration, rather than simply comparing the equipment price.

How to Select the Right Gas Analyzer for a Hazardous Area

A practical selection procedure is:

Step 1 — Identify the Gas

Determine which gases must be measured.

Step 2 — Determine the Concentration

Specify the expected minimum, normal and maximum concentration.

Step 3 — Define Accuracy

Determine the required measurement accuracy.

Step 4 — Select the Analytical Technology

Evaluate NDIR, TDL, electrochemical, paramagnetic, thermal conductivity, zirconia or GC technology as appropriate.

Step 5 — Define Process Conditions

Specify:

• Temperature

• Pressure

• Flow

• Moisture

• Dust

• Corrosive components

Step 6 — Determine Hazardous-Area Classification

Specify:

• Zone

• Gas group

• Temperature class

• Required protection concept

Step 7 — Determine Sample-System Requirements

Specify:

• Probe

• Filter

• Cooler

• Heated line

• Pressure regulation

• Pump

• Calibration system

Step 8 — Specify Communication

Determine whether the analyzer must provide:

• 4–20 mA

• Modbus

• Ethernet

• Relay outputs

• Other interfaces

Step 9 — Evaluate Certification

Confirm the actual certification and marking of the proposed analyzer.

Step 10 — Compare Lifecycle Cost

Consider:

• Purchase price

• Calibration

• Consumables

• Spare parts

• Service

• Maintenance

• Downtime

Hazardous-Area Gas Analyzer Checklist

Before issuing an RFQ, prepare the following information:

Process

• Gas composition

• Sampling point

• Temperature

• Pressure

• Flow

• Moisture

• Dust

• Corrosive components

Measurement

• Target gas

• Measurement range

• Accuracy

• Detection limit

• Response time

Hazardous Area

• Zone

• Gas group

• Temperature class

• Required certification

• Protection concept

System

• Sampling probe

• Sample-conditioning system

• Calibration

• Data acquisition

• Communication

• Installation

• Commissioning

Providing this information can significantly improve the quality of the technical quotation.

Common Mistakes When Selecting Hazardous-Area Gas Analyzers

Choosing Only on Price

A lower initial price does not necessarily represent a lower total cost.

Assuming CE Means ATEX

CE marking should not automatically be interpreted as hazardous-area certification.

Ignoring the Zone

The analyzer must be suitable for the actual classified area.

Ignoring Gas Group

The gas group must be compatible with the equipment certification.

Ignoring Temperature Class

The analyzer's surface-temperature classification must be suitable for the application.

Forgetting the Sample System

The sample-conditioning system is often just as important as the analyzer.

Modifying Certified Equipment

Unauthorized modifications can compromise certified protection.

Not Checking the Actual Certificate

Always verify the certificate and marking against the exact model and configuration.

Frequently Asked Questions

What is a hazardous-area Gas Analyzer?

A hazardous-area Gas Analyzer is an analyzer configured and certified, where applicable, for use in environments where potentially explosive gases, vapours or dust may be present.

Can any Industrial Gas Analyzer be installed in Zone 1?

No. The specific equipment must be suitable and certified for the relevant hazardous-area conditions, including the zone, gas group and temperature class.

What is the Gas Analyzer Working Principle?

It depends on the technology. Common principles include infrared absorption, electrochemical sensing, paramagnetic measurement, thermal conductivity, laser absorption and chromatographic separation.

What gases can hazardous-area analyzers measure?

Depending on the technology, they may measure O₂, H₂, CO, CO₂, CH₄, H₂S, SO₂, NOx, NH₃, moisture and other gases.

Is ATEX the same as CE?

No. CE marking is a broader conformity-marking framework, while ATEX specifically addresses equipment and protective systems intended for potentially explosive atmospheres.

Is IECEx the same as ATEX?

No. They are different certification frameworks, although both address equipment for explosive atmospheres. The project requirements should determine which certification is needed.

What information should I provide when ordering a hazardous-area Gas Analyzer?

Provide the gases to be measured, concentration range, process temperature and pressure, moisture, hazardous-area zone, gas group, temperature class and required certification.

Why is sample conditioning important?

Industrial process gases can contain moisture, dust, corrosive components and other contaminants. Proper sample conditioning helps deliver a representative sample to the analyzer.

How much does a Gas Analyzer cost in India?

The Gas Analyzer Price in India depends on the technology, measurement requirements, certification, sample-conditioning system, communication, installation and service requirements. A technical specification is required for an accurate quotation.

Conclusion

Selecting Gas Analyzers for Hazardous Areas requires a combination of analytical engineering and hazardous-area engineering.

The correct analyzer should be selected according to:

• Target gas

• Measurement range

• Accuracy

• Gas Analyzer Working Principle

• Process temperature

• Process pressure

• Moisture

• Dust

• Sample-conditioning requirements

• Hazardous-area zone

• Gas group

• Temperature class

• Certification

• Communication

• Maintenance requirements

For an Industrial Gas Analyzer, certification should never be considered separately from the complete installation. The analyzer, sample system, electrical equipment and associated components must be evaluated according to the actual application.

Similarly, when evaluating Gas Analyzer Price in India, compare complete and technically equivalent systems rather than comparing only the base analyzer price.

A properly selected and installed gas-analysis system can provide reliable process information while supporting safe and efficient plant operation.

Need Help Selecting a Gas Analyzer for a Hazardous Area?

Hazardous-area gas analysis can involve complex decisions regarding analytical technology, sample conditioning, certification and installation.

Our application team can help evaluate:

• Target gases

• Measurement range

• Analytical technology

• Gas Analyzer Working Principle

• Process temperature and pressure

• Sample-conditioning requirements

• Hazardous-area classification

• Zone and gas group

• Temperature class

• ATEX/IECEx requirements

• Calibration

• Communication

• Installation and commissioning

Talk to our application specialist

Share your process gas composition, measurement range, process conditions and hazardous-area classification with our application team to identify a suitable gas-analysis solution for your application.

Prosoft Automation — Industrial Gas Analyzers, Process Analysis & Analytical Instrumentation Solutions