IEC 60079-32-1 Explained: Electrostatic Hazards, Guidance

When discussing explosion hazards, engineers often focus on electrical equipment, hot surfaces, or mechanical sparks. However, one of the most overlooked ignition sources in hazardous areas is static electricity.

A small electrostatic discharge that is barely noticeable to a person can carry enough energy to ignite a flammable gas, vapor, or combustible dust atmosphere.

Electrostatic incidents have been responsible for numerous fires and explosions during activities such as tank truck loading, powder transfer, pneumatic conveying, and the handling of flexible intermediate bulk containers (FIBCs).

To address these risks, the industry relies on IEC 60079-32-1 – Explosive Atmospheres – Electrostatic Hazards, Guidance.

This standard provides practical guidance for identifying, assessing, and controlling electrostatic hazards in explosive atmospheres.

Because electrostatic charging can occur in almost every industrial process, understanding IEC 60079-32-1 is essential for engineers, operators, and safety professionals working in hazardous areas.

This article explains what IEC 60079-32-1 is, why it is important, and the major concepts that engineers should understand when evaluating electrostatic ignition hazards.

Quick Answer

What Is IEC 60079-32-1?

IEC 60079-32-1 is the international standard that provides guidance on preventing ignition hazards caused by static electricity in explosive atmospheres.

The standard covers:

• Electrostatic charging mechanisms.
• Electrostatic discharge phenomena.
• Ignition risks.
• Bonding and grounding practices.
• Handling of powders and liquids.
• Personnel grounding.
• Electrostatic risk assessment.

The objective of the standard is to reduce the likelihood that electrostatic discharges become ignition sources in hazardous areas.

Why Is IEC 60079-32-1 Important?

Static electricity is generated in countless industrial activities, often without operators realizing that a hazardous charge has accumulated.

Examples include:

• Liquid transfer operations.
• Tank truck loading.
• Pneumatic powder conveying.
• Filling and emptying containers.
• Movement of personnel.
• Use of plastic materials.
• Operation of conveyor systems.

Many of these activities occur routinely in industries that handle flammable materials.

Without proper controls, electrostatic discharges can ignite explosive atmospheres and result in catastrophic fires or explosions.

Who Uses IEC 60079-32-1?

The standard is widely used by industries where electrostatic charging may occur in the presence of flammable materials.

Typical users include:

• Process engineers.
• Electrical engineers.
• Safety engineers.
• Chemical plant operators.
• Tank terminal operators.
• Pharmaceutical manufacturers.
• Powder handling facilities.
• HAZOP and risk assessment teams.

Electrostatic hazards exist in many industries and therefore the principles of IEC 60079-32-1 have broad practical applications.

What Is Static Electricity?

Static electricity is an electrical charge that accumulates on the surface of materials due to the separation of positive and negative charges.

The charge remains stored until it is discharged to another object or to ground.

In industrial processes, electrostatic charging commonly occurs because of:

• Contact and separation of materials.
• Flow of liquids.
• Movement of powders.
• Friction between surfaces.
• Personnel movement.
• Use of insulating materials.

Under certain conditions, the stored energy may be sufficient to ignite an explosive atmosphere.

Why Is Static Electricity Dangerous in Hazardous Areas?

An explosive atmosphere requires three basic elements:

• Fuel.
• Oxidizer.
• Ignition source.

Electrostatic discharge can provide the ignition source.

Many flammable gases and dusts have extremely low minimum ignition energies, meaning that even relatively small electrostatic discharges may be capable of causing ignition.

For example, hydrogen and certain solvent vapors can be ignited by very small amounts of electrostatic energy.

As a result, electrostatic hazards must always be considered during hazardous area risk assessments.

How Is Static Electricity Generated?

Electrostatic charging can occur whenever materials contact and separate from one another.

Typical charging mechanisms include:

• Flowing liquids through pipes.
• Pouring powders into containers.
• Pneumatic conveying systems.
• Movement of conveyor belts.
• Personnel walking across insulated floors.
• Separation of plastic films.
• Handling of FIBCs and containers.

Because these activities are common throughout industry, electrostatic hazards can exist even in facilities that use very little electrical equipment.

Scope of IEC 60079-32-1

IEC 60079-32-1 provides guidance for identifying and controlling electrostatic hazards that may arise in explosive atmospheres.

The standard applies to processes involving flammable gases, vapors, combustible dusts, powders, liquids, and materials that can accumulate electrostatic charges.

The guidance covers:

• Electrostatic charging mechanisms.
• Electrostatic discharges.
• Ignition risks.
• Bonding and grounding practices.
• Electrostatic risk assessment.
• Personnel grounding.
• Handling of liquids and powders.
• Use of insulating materials.

The standard is widely applied across the oil and gas, chemical, pharmaceutical, food processing, and powder handling industries.

Major Topics Covered by IEC 60079-32-1

Although IEC 60079-32-1 contains extensive technical guidance, several key subjects form the basis of electrostatic hazard management:

• Generation of electrostatic charges.
• Types of electrostatic discharges.
• Electrostatic ignition mechanisms.
• Bonding and grounding methods.
• Control measures.
• Electrostatic risk assessment.

Understanding these topics is essential because static electricity is generated in numerous industrial processes that appear harmless under normal conditions.

Types of Electrostatic Discharges

IEC 60079-32-1 describes several forms of electrostatic discharge that can occur in industrial processes.

Each type of discharge has different ignition capabilities and may present different levels of risk.

• Spark discharges.
• Brush discharges.
• Propagating brush discharges.
• Cone discharges.
• Corona discharges.

The ability of these discharges to ignite explosive atmospheres depends on the energy released and the sensitivity of the flammable material.

Spark Discharges

Spark discharges occur when an electrically charged conductive object suddenly discharges to another conductive object or to ground.

Examples include:

• Ungrounded metal containers.
• Tank trucks.
• Portable metal equipment.
• Process vessels.
• Metal drums.

Spark discharges can release significant energy and are capable of igniting many flammable gases and dusts.

Brush Discharges

Brush discharges occur from charged insulating materials such as plastics and synthetic surfaces.

Examples include:

• Plastic sheets.
• Plastic containers.
• Plastic piping.
• Coated surfaces.
• Insulating hoses.

Although brush discharges generally release less energy than spark discharges, they can still ignite sensitive gases and vapors.

Propagating Brush Discharges

Propagating brush discharges are high-energy discharges that may occur in certain insulating structures, particularly where conductive layers are separated by insulating materials.

These discharges are considered especially hazardous because they may possess sufficient energy to ignite a wide range of explosive atmospheres.

Examples may include:

• Some flexible liners.
• Certain coated materials.
• Multi-layer insulating structures.

IEC 60079-32-1 provides specific guidance for avoiding conditions that could produce propagating brush discharges.

Cone Discharges

Cone discharges may occur during the filling of powders and granular materials into silos, hoppers, or containers.

As the material forms a cone-shaped pile, electrostatic charges can accumulate and eventually discharge.

Cone discharges are particularly important in:

• Powder processing facilities.
• Pharmaceutical plants.
• Grain handling systems.
• Chemical powder manufacturing.
• Food processing facilities.

Certain combustible dusts may be particularly sensitive to this type of ignition source.

Corona Discharges

Corona discharges occur in regions where strong electric fields ionize the surrounding air without producing a complete spark.

These discharges generally release lower levels of energy and are less likely to ignite many explosive atmospheres.

However, their ignition capability should still be evaluated as part of an electrostatic risk assessment.

Bonding and Grounding

Bonding and grounding are among the most effective methods for preventing the accumulation of dangerous electrostatic charges on conductive objects.

Bonding involves electrically connecting conductive objects together so that they remain at the same electrical potential.

Grounding involves connecting conductive objects to earth so that accumulated charges can dissipate safely.

Typical applications include:

• Tank truck loading operations.
• Storage tanks.
• Process vessels.
• Metal drums.
• Transfer piping systems.
• Portable containers.

Proper bonding and grounding practices can significantly reduce the risk of electrostatic spark discharges.

Electrostatic Hazards During Liquid Transfer

The flow of liquids through pipes and hoses can generate significant electrostatic charges, particularly when:

• Low-conductivity liquids are handled.
• Flow velocities are high.
• Splash filling occurs.
• Filters are installed.
• Two-phase flow is present.

Examples of low-conductivity liquids include:

• Gasoline.
• Diesel fuel.
• Jet fuel.
• Hydrocarbon solvents.

IEC 60079-32-1 provides guidance for controlling these hazards through grounding, bonding, and appropriate operating procedures.

Advantages of IEC 60079-32-1

IEC 60079-32-1 provides practical guidance for identifying and controlling one of the most overlooked ignition sources in hazardous areas: static electricity.

Without a systematic approach to electrostatic hazard management, facilities may unknowingly create conditions where electrostatic discharges can ignite explosive atmospheres.

Key advantages of IEC 60079-32-1 include:

• Provides internationally recognized guidance for electrostatic hazard control.
• Addresses both gas and combustible dust atmospheres.
• Supports effective bonding and grounding practices.
• Helps prevent electrostatic ignition incidents.
• Provides guidance for liquid and powder handling operations.
• Supports electrostatic risk assessments.
• Improves process safety management.
• Promotes safer operating procedures.

For many industries, compliance with IEC 60079-32-1 forms an important part of their overall explosion prevention strategy.

Limitations of IEC 60079-32-1

Although IEC 60079-32-1 provides comprehensive guidance, electrostatic hazards are often highly dependent on process conditions and material properties.

Some limitations include:

• Electrostatic charging can be difficult to predict.
• Material properties may vary significantly.
• Environmental conditions can affect charging behavior.
• Some hazards require specialized testing.
• Electrostatic risk assessments often rely on engineering judgment.
• Process modifications may require reassessment.

For these reasons, electrostatic hazard evaluations should be performed by competent personnel familiar with the process and the materials involved.

Electrostatic Hazards During Powder Handling

Powder processing operations are among the most common sources of electrostatic charging.

Examples include:

• Pneumatic conveying.
• Filling and emptying bags.
• Powder transfer operations.
• Mixing and blending processes.
• Grinding operations.
• Silo filling.

Fine powders can accumulate substantial electrostatic charges during handling, particularly when conveyed through insulating pipes or flexible hoses.

Certain powders can generate electrostatic discharges with sufficient energy to ignite combustible dust clouds.

Electrostatic Hazards During Tank Truck Loading

Tank truck loading operations represent one of the best-known electrostatic hazards in industry.

Electrostatic charges can be generated by:

• Flowing low-conductivity liquids.
• Splash filling.
• High loading velocities.
• Filters and strainers.
• Two-phase flow conditions.

If the tank truck is not properly bonded and grounded, dangerous charge accumulation may occur and result in spark discharges.

IEC 60079-32-1 therefore provides detailed guidance on bonding and grounding practices for liquid transfer operations.

Flexible Intermediate Bulk Containers (FIBCs)

Flexible Intermediate Bulk Containers, commonly known as bulk bags or big bags, can present significant electrostatic hazards.

The movement and filling of powders inside FIBCs can generate substantial electrostatic charges.

IEC 60079-32-1 recognizes several categories of FIBCs:

• Type A.
• Type B.
• Type C.
• Type D.

Each type has different electrostatic properties and different limitations regarding use in hazardous areas.

The incorrect selection of FIBCs has been associated with several serious industrial accidents.

Personnel Electrostatic Charging

People themselves can become sources of electrostatic ignition.

Walking on insulated floors, removing protective clothing, or handling certain materials can result in significant charge accumulation on the human body.

Control measures may include:

• Conductive footwear.
• Antistatic clothing.
• Conductive flooring.
• Humidity control.
• Personnel grounding systems.

Personnel charging is particularly important in facilities handling sensitive gases or powders with very low minimum ignition energies.

Use of Insulating Materials

Insulating materials can accumulate electrostatic charges because they do not allow charges to dissipate easily.

Examples include:

• Plastic containers.
• Plastic pipes.
• Plastic films.
• Synthetic fabrics.
• Coated surfaces.
• Insulating hoses.

The use of insulating materials in hazardous areas should therefore be carefully evaluated as part of an electrostatic risk assessment.

Electrostatic Risk Assessment

IEC 60079-32-1 encourages the use of systematic risk assessments to identify situations where electrostatic charging may create ignition hazards.

A typical assessment may consider:

• The flammable material involved.
• The minimum ignition energy.
• The charging mechanisms present.
• The likelihood of charge accumulation.
• The effectiveness of control measures.
• The consequences of ignition.

The results of the assessment help determine whether additional safeguards are required.

Common Mistakes in Electrostatic Hazard Management

Experience throughout the industry has shown that several deficiencies occur repeatedly.

Examples include:

• Assuming that grounding alone eliminates all electrostatic hazards.
• Using insulating hoses in hazardous areas.
• Ignoring personnel charging.
• Using unsuitable FIBCs.
• Ignoring low-conductivity liquids.
• Failing to bond portable containers.
• Overlooking dust accumulation hazards.
• Failing to reassess hazards after process modifications.

Many of these deficiencies have contributed to fires and explosions throughout the process industries.

Relationship Between IEC 60079-32-1 and Other Standards

IEC 60079-32-1 forms part of the broader hazardous area framework and should be used together with several other IEC 60079 standards.

Standard	Purpose
IEC 60079-10-1	Classification of explosive gas atmospheres.
IEC 60079-10-2	Classification of combustible dust atmospheres.
IEC 60079-14	Selection and installation of electrical equipment.
IEC 60079-31	Equipment protection for combustible dust atmospheres.
IEC 60079-32-1	Electrostatic hazards and guidance.

Together, these standards provide a comprehensive approach to managing ignition risks in hazardous areas.

Why Engineers Should Understand IEC 60079-32-1

Electrostatic discharges are among the most frequently overlooked ignition sources because they are often invisible and difficult to predict.

A basic understanding of IEC 60079-32-1 helps engineers:

• Recognize electrostatic hazards.
• Improve bonding and grounding practices.
• Evaluate powder and liquid handling operations.
• Conduct better risk assessments.
• Reduce ignition risks.
• Improve operational safety.
• Prevent fires and explosions.

Because electrostatic charging occurs in countless industrial processes, IEC 60079-32-1 remains one of the most important guidance documents for engineers and safety professionals working in hazardous areas.

Frequently Asked Questions (FAQ)

What is IEC 60079-32-1?

IEC 60079-32-1 is the international standard that provides guidance for identifying and controlling electrostatic hazards in explosive atmospheres. It addresses electrostatic charging mechanisms, ignition risks, and protective measures for industrial processes involving flammable gases, vapors, and combustible dusts.

Does static electricity really cause explosions?

Yes. Electrostatic discharges have been responsible for numerous industrial fires and explosions involving flammable liquids, gases, and combustible dusts. Even small discharges may have sufficient energy to ignite sensitive explosive atmospheres.

What is the difference between bonding and grounding?

Bonding electrically connects conductive objects together so that they remain at the same electrical potential. Grounding connects those objects to earth so that accumulated charges can safely dissipate.

Can people become electrostatic ignition sources?

Yes. Personnel can accumulate significant electrostatic charges through movement, clothing, and contact with insulating materials. In certain situations, these charges may be sufficient to ignite sensitive explosive atmospheres.

Are all plastics dangerous in hazardous areas?

Not necessarily. However, insulating materials such as plastics can accumulate electrostatic charges and therefore require careful evaluation before being used in hazardous areas.

Why are low-conductivity liquids a concern?

Low-conductivity liquids such as gasoline and hydrocarbon solvents can accumulate electrostatic charges during transfer operations, increasing the risk of spark discharges if proper controls are not implemented.

Conclusion

IEC 60079-32-1 is one of the most important guidance documents for managing ignition risks caused by static electricity in explosive atmospheres.

The standard recognizes that electrostatic charging occurs in countless industrial processes and that static electricity can become a significant ignition source even when no electrical faults or hot surfaces are present.

Proper bonding, grounding, equipment selection, personnel protection, and electrostatic risk assessments are essential elements of controlling these hazards.

A solid understanding of IEC 60079-32-1 helps engineers identify overlooked ignition sources, improve process safety, and reduce the likelihood of fires and explosions in facilities handling flammable gases, liquids, and combustible dusts.

Technical Review

References

• IEC 60079-32-1 – Explosive Atmospheres – Electrostatic Hazards, Guidance.
• IEC 60079-10-1 – Explosive Atmospheres – Classification of Areas – Explosive Gas Atmospheres.
• IEC 60079-10-2 – Explosive Atmospheres – Classification of Areas – Combustible Dust Atmospheres.
• IEC 60079-31 – Explosive Atmospheres – Equipment Dust Ignition Protection by Enclosure "t".
• IECEx System – International Certification System for Equipment Used in Explosive Atmospheres.
• International Electrotechnical Commission (IEC).
• EN IEC 60079-32-1 – Explosive Atmospheres – Electrostatic Hazards, Guidance.