IEC 60079-29-2 Explained: Selection, Installation, Use and Maintenance of Gas Detectors

A gas detector is only useful when it is correctly selected, properly installed, operated as intended and maintained throughout its service life. This is the main focus of IEC 60079-29-2.

While detector performance standards address how detection equipment is evaluated, IEC 60079-29-2 focuses on its practical application: selection, installation, safe use and maintenance.

The standard is relevant to engineers, system designers, commissioning teams, operators and maintenance personnel working with gas detection equipment in industrial facilities.

What Is IEC 60079-29-2?

The full title of the standard is:

The source identifies IEC 60079-29-2:2015, Edition 2.0, published on 16 March 2015, with a stability date of 2028. It provides guidance and recommended practice rather than serving as the primary detector performance standard.

The Four Stages of the Gas Detector Lifecycle

The most practical way to understand IEC 60079-29-2 is to consider the complete lifecycle of gas detection equipment.

Stage	Main question
Selection	Which detector is suitable for the target gas, application and environment?
Installation	Where and how should the detector be installed?
Use	How should the equipment be operated safely?
Maintenance	How should detector performance be checked and maintained?

These stages are connected. A suitable detector can still be ineffective if it is installed in the wrong location, operated incorrectly or poorly maintained.

Detector Selection: Start With the Gas

The first question should not simply be which detector is normally used for a particular facility. It should be which gas or vapour needs to be detected, and how will it behave if released?

Factors that can influence detector selection and location include:

• Relative density.
• Flammability and physical properties.
• Vapour pressure and temperature.
• Release conditions.
• Ventilation and air movement.
• Environmental conditions.

These factors influence how gas or vapour disperses and where it may accumulate. The selected detector must be appropriate for the target gas and intended detection function.

Gas vs Vapour

A gas may be released directly from a pressurised process, while vapour can be produced when a liquid evaporates. The behaviour of a release depends on the material, temperature, release conditions and surrounding environment.

For example, a hydrocarbon liquid release can produce vapour whose movement depends on evaporation, temperature and ventilation. These conditions should be considered when selecting and positioning detection equipment.

Gas Density and Detector Location

Relative density is an important consideration when determining detector location. A gas heavier than air may accumulate in low areas under suitable conditions, while a lighter gas may rise toward elevated or poorly ventilated locations.

However, density alone does not determine the correct detector position. Release velocity, temperature, ventilation, air movement, process equipment and surrounding structures can all influence gas dispersion.

Detector placement should therefore be based on the actual release scenario rather than a simple rule such as installing every heavy-gas detector low or every light-gas detector high.

Ventilation and Gas Dispersion

Ventilation can significantly affect how a released gas disperses. Air movement may dilute a release, redirect the gas cloud or create areas where gas can accumulate.

When evaluating detector locations, consider:

• Potential release points.
• Airflow direction and ventilation equipment.
• Potential stagnant zones.
• Structures that obstruct gas movement.
• Process equipment layout.

The objective is to position detectors where they have a reasonable opportunity to encounter the gas release they are intended to detect.

Fixed Gas Detection

Fixed detectors are permanently installed at selected locations within an industrial facility. Typical applications include:

• Oil and gas processing areas.
• Petrochemical facilities.
• Compressor stations and pump areas.
• Tank farms.
• Loading and unloading facilities.
• Gas processing units.

A fixed detector may provide signals to a controller, alarm system, shutdown system or other safety-related equipment, depending on the facility design.

Identify Potential Release Sources

Detector placement should begin by identifying where flammable gas or vapour could realistically be released. Depending on the process, potential sources may include:

• Flanges and valves.
• Pumps, compressors and mechanical seals.
• Sampling points and process connections.
• Drains and vents.
• Pressure-relief systems.

The actual sources depend on the process and equipment configuration. A detector should not be positioned solely because a mounting location is convenient. Structures may shield the sensor from a gas flow, while excessive distance from a release source may delay detection.

Open-Path Gas Detection

Open-path detectors use an optical path to detect gas over a distance rather than measuring concentration at a single point. IEC 60079-29-2 includes considerations for this type of detection.

Installation considerations include:

• Beam path and alignment.
• Obstructions.
• Mounting stability.
• Environmental visibility and atmospheric conditions.
• Potential movement of the gas cloud.

The optical path must remain suitable for the intended detection function during operation.

Environmental and Installation Conditions

Gas detectors may operate in demanding industrial environments. Relevant factors can include:

• Ambient temperature and humidity.
• Dust, condensation and contamination.
• Vibration and mechanical impact.
• Corrosive atmospheres.
• Sunlight and atmospheric conditions.

The equipment must be suitable for the actual operating environment, in addition to meeting its gas detection and hazardous-area requirements.

Installation Quality

Installation should consider the detector's intended function as well as practical access for inspection and maintenance.

• Mounting position and orientation.
• Mechanical protection.
• Cable routing and electrical connections.
• Suitable cable glands, conduit and enclosure entries where applicable.
• Earthing and bonding where required by the equipment design.
• Access for calibration, inspection and sensor replacement.

For equipment installed in hazardous areas, the electrical installation must also comply with the requirements applicable to its selected Type of Protection.

Selecting the Measuring Principle

Different gas detection technologies are suitable for different gases and applications. IEC 60079-29-2 includes guidance on measuring principles, including a dedicated normative annex.

Examples of industrial detection technologies include:

• Catalytic combustion.
• Infrared absorption.
• Open-path infrared detection.
• Other application-specific sensing technologies.

The appropriate technology depends on the target gas, measurement requirements and environmental conditions. Selection should be based on the application rather than familiarity with a particular technology.

Portable and Transportable Gas Detectors

Portable Gas Detectors

Portable detectors are carried by personnel or used temporarily for personal or area monitoring. Typical applications include:

• Maintenance and inspection.
• Confined-space activities.
• Gas-free work.
• Temporary monitoring.

Users need to understand the detector's operating procedures, alarm functions, limitations and response requirements. A portable detector should not be treated as an instrument that can simply be switched on and ignored.

Transportable Gas Detectors

Transportable detectors can be moved between locations and may provide a more substantial instrument arrangement than equipment intended primarily for personal carrying. IEC 60079-29-2 addresses fixed installations, transportable equipment and the safe use of portable equipment.

Gas-Free Work and Oxygen Measurement

Gas-Free Work

Gas detection can support gas-free work procedures. Before certain maintenance or hot-work activities, the atmosphere may need to be checked to determine whether dangerous concentrations are present.

IEC 60079-29-2 identifies gas-free work permits among the applications of gas detection. Readings must be interpreted according to the site's permit-to-work procedure and applicable safety requirements.

Oxygen Measurement and Inertisation

IEC 60079-29-2 also provides guidance concerning oxygen deficiency and oxygen measurement for certain applications.

This is relevant to inertisation, where reducing oxygen concentration forms part of an explosion-prevention strategy. Oxygen concentration can become a critical process-safety parameter, so the measurement equipment and operating procedures must be appropriate for the application.

Alarm Functions and System Integration

Gas detection equipment may provide signals that initiate alarms or other safety-system actions. The overall alarm philosophy belongs to the facility's safety system rather than to the detector alone.

Depending on the system design, relevant considerations include:

• Alarm levels and operator notification.
• Shutdown functions and reset procedures.
• Fault indication and loss-of-signal response.
• Interfaces with controllers and safety systems.

The intended functions and responses should be defined through the project safety philosophy, system design and manufacturer documentation.

Use, Training and Operating Procedures

IEC 60079-29-2 includes a dedicated section addressing training of operational personnel. Training is important because equipment is only effective when users understand its operation, alarms and limitations.

Depending on their responsibilities, personnel may need to understand:

• How to start and check the detector.
• How to interpret readings.
• How alarms operate and how to respond.
• How to identify equipment faults.
• When testing, calibration or maintenance is required.

Training should be appropriate to the role of each person using, maintaining or supervising the equipment.

Maintenance and Calibration

Detector performance can change during service. Potential causes include sensor ageing, contamination, environmental exposure, mechanical damage, loss of calibration, blocked sampling paths, optical contamination and component deterioration.

The maintenance programme should consider the detector technology, application, manufacturer's instructions and site requirements.

Calibration

Calibration checks detector response against a known reference. The method depends on the sensing principle and equipment design.

A calibration programme may define:

• Calibration method and reference gas where applicable.
• Calibration interval.
• Acceptance criteria.
• Documentation requirements.
• Corrective action when calibration fails.

IEC 60079-29-2 provides recommendations for establishing maintenance and calibration intervals. Manufacturer instructions and applicable site requirements must also be considered.

Calibration vs Functional Checking

Calibration and functional checking are not automatically the same activity. A functional check confirms that the detector and associated functions respond as intended.

Depending on the equipment, checks may include:

• Sensor response.
• Alarm operation and display indication.
• Output signals.
• Fault indication.
• Communication with the control system.

The actual procedure should follow the manufacturer's instructions and site procedures.

Maintenance Records

Maintenance activities should be documented. IEC 60079-29-2 includes an informative annex containing a typical maintenance record for flammable gas detectors.

A useful record can include:

• Detector identification and location.
• Inspection date and test results.
• Calibration information.
• Faults identified and corrective actions.
• Technician identification.
• Next scheduled activity.

Maintenance Intervals

There is no single maintenance interval that is automatically appropriate for every detector and application. The interval should consider manufacturer recommendations, sensor technology, operating environment, gas exposure, historical performance, regulatory requirements and site safety requirements.

What Happens When a Detector Fails?

A gas detection system should have a defined response to detector faults. Depending on the system architecture, a fault may result in:

• A fault alarm or loss-of-signal indication.
• Maintenance notification.
• Use of redundant detector information, where provided.
• Other safety-system actions defined by the facility design.

The appropriate response depends on the facility's safety philosophy and control architecture. It should not be assumed that every detector failure triggers the same automatic shutdown action.

Gas Detection vs Hazardous-Area Classification

Gas detection and hazardous-area classification are related but different engineering activities.

Subject	Main purpose
Hazardous-area classification	Defines the likelihood and extent of explosive atmospheres.
Gas detection	Detects or measures gas concentrations.
IEC 60079-29-2	Provides guidance for selecting, installing, using and maintaining gas detection equipment.

Gas detection should not be treated as a substitute for hazardous-area classification. Both activities serve different purposes in the overall safety design.

IEC 60079-29-2 vs IEC 60079-29-1

The two standards have complementary historical roles.

Standard	Main focus
IEC 60079-29-1	Performance requirements for detectors for flammable gases.
IEC 60079-29-2	Selection, installation, safe use and maintenance.

IEC 60079-29-1 was historically focused on detector performance, while Part 29-2 addressed practical application. The source material identifies IEC 60079-29-1:2016+A1:2020 as withdrawn and replaced by IEC 60079-29-0:2025.

This change should not automatically be interpreted as withdrawal of IEC 60079-29-2. The source identifies IEC 60079-29-2:2015 as Edition 2.0 with a stability date of 2028. Confirm the latest applicable publication and project requirements before issuing specifications or procurement documents.

Procurement Checklist

Before purchasing or approving a gas detector, review the following information against the project datasheet and specification.

Review item	What to confirm
Target gas	Specific gas or vapour to be detected.
Detection function	Required detection purpose and measuring range.
Equipment type	Fixed, portable or transportable.
Measuring principle	Suitability for the target gas and application.
Hazardous area	Zone and installation conditions.
Ex certification	Applicable protection concept, EPL, gas subgroup and temperature class, where relevant.
Ambient conditions	Site temperature, ingress protection and environmental exposure.
Outputs and interfaces	Required signals, alarms and control-system connections.
Calibration and maintenance	Methods, intervals and access requirements.
Documentation	Manufacturer information, applicable certificates and maintenance instructions.

Design Checklist for Fixed Gas Detection

For a fixed installation, the engineering review should additionally consider:

• Potential gas release sources.
• Gas density and release behaviour.
• Ventilation patterns and airflow.
• Potential accumulation points.
• Detector coverage and mounting location.
• Physical obstructions.
• Accessibility for inspection and maintenance.
• Cable routing and electrical installation.
• Control-system interfaces and alarm philosophy.

This checklist is useful during FEED, detailed engineering, vendor document review and commissioning because detector selection, placement and maintenance are closely connected.

Common Engineering Mistakes

Choosing a Detector Based Only on Gas Type

The target gas is important, but the environment, measuring range, installation arrangement and hazardous-area requirements must also be considered.

Placing Detectors Without Studying Gas Movement

Detector location should consider release sources, gas properties, ventilation and airflow.

Installing Detectors Where They Cannot Be Maintained

A suitable detector can become an operational problem if personnel cannot safely access it for inspection, calibration or sensor replacement.

Ignoring Ventilation

Air movement can significantly influence where gas accumulates and where detection is effective.

Assuming Calibration Alone Is Enough

Calibration is one part of maintenance. Functional checks, inspection, cleaning and other activities may also be required, depending on the equipment.

Ignoring Personnel Training

Users need to understand detector operation, alarm response and equipment limitations.

Frequently Asked Questions

What is IEC 60079-29-2?

It provides guidance and recommended practice for selecting, installing, safely using and maintaining gas detectors for flammable gases and oxygen.

What edition is identified in the source?

The source identifies IEC 60079-29-2:2015, Edition 2.0, published on 16 March 2015, with a stability date of 2028.

Does IEC 60079-29-2 cover detector performance?

Its primary focus is selection, installation, safe use and maintenance. Detector performance is addressed by the relevant performance standards.

Does it cover fixed gas detectors?

Yes. It provides guidance for fixed installations as well as transportable equipment and safe use of portable equipment.

Does it cover oxygen measurement?

Yes. The standard includes guidance concerning oxygen measurement and certain applications involving oxygen deficiency and inertisation.

Does it cover open-path detection?

Yes. The source identifies specific considerations for open-path gas detection.

Does it specify exactly where every detector must be installed?

No universal location applies to every installation. Detector placement depends on the target gas, release sources, ventilation, process layout and other application-specific factors.

Does it specify one universal calibration interval?

No. It provides guidance for establishing maintenance and calibration intervals. Manufacturer instructions, site requirements and applicable regulations must also be considered.

Conclusion

IEC 60079-29-2 addresses the practical lifecycle of gas detection equipment: selection, installation, use and maintenance.

The effectiveness of a gas detection system depends on more than the sensor itself. Gas properties, release sources, ventilation, detector location, installation quality, operating procedures, personnel training and maintenance all influence its performance.

For hazardous-area projects, IEC 60079-29-2 is relevant to engineers, system designers, commissioning teams, operators and maintenance personnel. The objective is to select appropriate equipment, install it where it can detect the intended hazard, operate it correctly and maintain it so that it remains fit for purpose.

Related Reading

• IEC 60079-29-1 Explained: Gas Detectors for Explosive Atmospheres
• IEC 60079-10-2 Explained: Classification of Areas – Combustible Dust Atmospheres
• Equipment Protection Level Explained

Technical Basis

References

• IEC 60079-29-2:2015 – Explosive atmospheres – Part 29-2: Gas detectors – Selection, installation, use and maintenance of detectors for flammable gases and oxygen.
• IEC 60079-29-1 – Gas detectors – Performance requirements of detectors for flammable gases.
• IEC 60079-29-4 – Gas detectors – Performance requirements of open path detectors for flammable gases.
• IEC 60079-10-1 – Explosive atmospheres – Classification of areas – Explosive gas atmospheres.
• IEC 60079-10-2 – Explosive atmospheres – Classification of areas – Combustible dust atmospheres.