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An electrostatic ignition source is a discharge resulting from the generation and accumulation of electrostatic charges. Electrostatic charge generation most frequently occurs when any two materials – liquids and/or solids – make contact with each other and then separate.

The generation and accumulation of electrostatic charge is not generally in and of itself hazardous. Rather, a hazard is created when the accumulated charges give rise to electrostatic discharges that are sufficiently energetic to ignite a surrounding flammable liquid or gas as well as a combustible dust atmosphere.

For an electrostatic hazard to occur, the following criteria must be fulfilled; there should be a flammable atmosphere which may be gases, vapours, suspended droplets or suspended dusts; there should be a process giving rise to charge generation, the charge must accumulate, the charge accumulation must be large enough to produce an electrical breakdown of the local atmosphere and the electrostatic discharges so produced must be energetic enough to ignite the flammable atmosphere.

To prevent the accumulation of hazardous levels of electrostatic charge and hence energetic sparks, the electrical resistance to the ground of all conductive items of a plant including metal pipes, equipment, vessels, and containers should be checked. If the resistance is greater than 10 ohms, direct ground connection will be required. Additionally, it is important that the ground connections are checked regularly, and that their purpose is known to the operators and maintenance personnel.

Understanding static electricity: charge generation, charge accumulation and discharge

To control and assess electrostatic hazards, the first step is to understand how it is generated. Static electricity can give rise to a fire or explosion hazard when three conditions occur:

Static electricity charges are generated (charge generation): When two different materials come into contact, electrons may prefer one material over the other, leading to an electron transfer across the interface. If these materials are separated, the electrons might not fully return to their original material. In cases where both materials are good conductors, the transferred charge will return through conduction at the last contact point, leaving no trace of the charge exchange. However, if one or both materials are insulators, the transferred charge cannot move back easily, resulting in one material becoming positively charged and the other negatively charged.

Static charges accumulate: Static electric charges accumulate on an object’s surface when the rate of charge generation exceeds the rate of discharge. This phenomenon, known as charge accumulation, occurs when the balance between the incoming and outgoing charges is disrupted. Depending on their volume resistivity, solid materials are categorized into three distinct groups to reflect their ability to accumulate or dissipate electrostatic charges.

  • low resistivity powders, with volume resistivities 𝜌≤1 𝑀Ω∗𝑚
  • medium resistivity powders, with volume resistivities 1 𝑀Ω∗𝑚<𝜌≤10 𝐺Ω∗𝑚
  • high resistivity powders, with volume resistivities 𝜌>10 𝐺Ω∗𝑚 Low resistivity powders can retain the charge although they are in an earthed container or in contact with earthed material.

Electrostatic Discharge (ESD): An electrostatic discharge (ESD) of sufficient energy can happen when there’s a hazardous atmosphere present, triggered by the accumulation of electrostatic charge on an object. As the charge builds up, the electrical energy associated with it increases, which is linked to the object’s electrical potential or voltage, its size, and how close it is to ground potential. The danger from the charge on a liquid or solid material arises only if it is released to another body, typically to the earth. When there’s a potential difference between two objects, as they get closer, the electric field between them intensifies until it surpasses the air’s breakdown strength. At this critical point, the air becomes ionized, allowing charges to move from the higher voltage object to the lower voltage one. This movement of charge is what we refer to as an electrostatic discharge.

Some risks associated with static electricity:

  • Electric shock due to the flow of current through the body, causing a person everything from an uncomfortable zap to falls, burns, or stopping the heart
  • Fires or explosions due to the ignition of flammable or explosive mixtures
  • Production disturbances in the processing of paper, plastics, composites, powder, granules, and liquids
  • Damage to electronic equipment and components from electrostatic discharge (ESD)
  • Damage to mechanical components such as bearings due to sparking through the oil films on the bearing surface

Electrostatic Hazard Assessment (EHA)

Electrostatic Hazard Assessment (EHA) is a critical safety process in industrial settings, particularly in environments where combustible materials are processed or handled. It involves the systematic evaluation of risks associated with the accumulation and discharge of static electricity, which can be a significant ignition source for fires or explosions. Key components of EHA typically include:

Identification of Static Electricity Sources: Determining where and how static charges are generated in the facility, often through activities such as material handling, processing, or the movement of personnel.

Assessment of Material Properties: Analyzing the properties of materials being handled, such as their ability to accumulate static charge and their combustibility or flammability.

Evaluation of Environmental Conditions: Considering factors like humidity and temperature, which can affect the generation and dissipation of static electricity.

Inspection of Equipment and Infrastructure: Checking for proper grounding and bonding of equipment, which are essential for safely dissipating static charges.

Analysis of Work Practices: Reviewing operational procedures and practices to identify activities that may contribute to static electricity risks.

Risk Assessment: Evaluating the likelihood of static electricity leading to ignition and the potential consequences of such events.

Development of Control Measures: Implementing strategies to mitigate identified risks, which may include improving grounding and bonding systems, altering material handling processes, changing environmental conditions, or using antistatic devices.

Training and Awareness: Educating employees about the risks associated with static electricity and training them in safe work practices and emergency procedures.

Documentation and Compliance: Ensuring that the findings and recommendations of the EHA are well-documented and that the facility complies with relevant safety standards and regulations.

Continuous Monitoring and Review: Regularly monitoring the effectiveness of control measures and reviewing the EHA to keep it up-to-date with any changes in processes, materials, or equipment.

Prime Process Safety Center Electrostatic Hazard Assessment

Electrostatic hazard analysis focuses on hazards that can be caused by static charge generation, build-up, and discharges that could serve as ignition sources to cause fire or explosion hazards. Prime Process Safety Center’s Electrostatic Hazard Assessment/Analysis will:

  • Visit to your facility to review and evaluate the efficacy of existing static hazard control measures and determine the missing measures
  • Identify all possible flammable atmospheres and establish the energy required to ignite them. For all powders it is necessary to test samples of the material being handled (i.e., MIE: Minimum Ignition Energy);
  • Identify those places where static charge could be generated and accumulated (considering the characteristics of the substances handled, the processes and the operating conditions);
  • Where static charge is generated and allowed to accumulate, sooner or later there will be an electrostatic discharge. The next stage of the assessment is to quantify the energy of discharges that could occur;
  • Review and evaluate the efficacy of existing static hazard control measures and determine the missing measures (if applicable) in your facilities
  • Recommend any further, alternative, or different safety measures for controlling static hazards in your facilities

Provide supporting services to assist you in implementing changes and safety measures to prevent static hazards as an ignition source of explosions and flash-fires

Why perform electrostatic hazard assessment

Performing an Electrostatic Hazard Assessment in the process industry is vital due to the inherent risks associated with static electricity in environments handling flammable or combustible materials. In industries such as chemical manufacturing, pharmaceuticals, and petrochemicals, static charges can accumulate and, if not properly controlled, lead to ignition of flammable vapors, gases, or dust, resulting in fires or explosions. These assessments help in identifying and evaluating the sources of electrostatic generation, the potential accumulation points, and the effectiveness of existing grounding and bonding systems. By systematically analyzing these factors, industries can implement appropriate safety measures to mitigate the risk of static-induced incidents. This not only ensures compliance with safety regulations but also enhances overall operational safety, protecting both personnel and assets from the potentially devastating consequences of electrostatic discharges.

Why Work with Prime Process Safety Center

  • Expertise in Static Electricity Risks: Our team possesses specialized knowledge in identifying and managing risks associated with static electricity, particularly in industrial environments.
  • Customized Assessment Strategies: We tailor our Electrostatic Hazard Assessments to your specific industry and operational context, ensuring a focused and relevant evaluation.
  • Advanced Diagnostic Tools: Utilizing state-of-the-art diagnostic equipment, we accurately measure and analyze static electricity generation and accumulation in your facility.
  • Comprehensive Risk Management: Beyond mere identification, we provide comprehensive strategies for managing and mitigating electrostatic risks, including grounding and bonding solutions.
  • Regulatory Compliance Assurance: Our assessments ensure that your operations comply with relevant industry standards and regulatory requirements, helping you avoid potential legal and financial repercussions.
  • Training and Education Services: We offer training programs to educate your staff about electrostatic hazards and safe practices, fostering a culture of safety and awareness.
  • Proven Track Record: With a history of successful assessments and interventions, our expertise is backed by tangible results in improving workplace safety.
  • Ongoing Support and Consultation: We provide continuous support and follow-up consultations to ensure that implemented safety measures are effective and sustainable.
  • Innovative Solutions: Our team stays abreast of the latest developments in electrostatic safety, offering you innovative and effective solutions.
  • Detailed Reporting and Documentation: We provide thorough documentation of our assessments, including clear explanations and actionable recommendations, aiding in decision-making and compliance tracking.
  • Own Laboratory: Prime Process Safety Center has a state-of-the-art laboratory (located in Houston Texas) which provides accurate, reliable and defensible data that meets industry and regulatory standards. Our laboratory facilities are equipped to conduct testing needed to reaction mechanisms or process and materials.


1. What is Electrostatic Hazard Assessment?

It’s an evaluation process to identify and assess risks associated with electrostatic charges in industrial environments, which can lead to fires, explosions, or other safety hazards.

2. Why is Electrostatic Hazard Assessment important in industrial settings?

It’s crucial for preventing accidents caused by static electricity, particularly in industries handling flammable materials, where electrostatic discharge can ignite vapors, dust, or gases.

3. What industries commonly require Electrostatic Hazard Assessments?

Industries that handle flammable liquids, gases, powders, or solvents, such as chemical manufacturing, pharmaceuticals, petrochemicals, and food processing, typically require these assessments.

4. How is an Electrostatic Hazard Assessment conducted?

It involves measuring and evaluating static charge generation and accumulation, identifying potential ignition sources, and assessing the effectiveness of existing grounding and bonding systems.

5. What are the common sources of electrostatic hazards in industries?

Common sources include the flow of liquids or powders through pipes or chutes, the mixing of materials, and the friction or separation of materials in process operations.

6. What are grounding and bonding, and why are they important?

Grounding and bonding are techniques used to prevent the accumulation of static electricity. Grounding ensures that equipment is at the same electrical potential as the earth, while bonding equalizes electrical potentials between different pieces of equipment.

7. How often should Electrostatic Hazard Assessments be conducted?

Regular assessments are recommended, especially when there are changes in processes, materials, or equipment that could affect static electricity risks.

8. What are the key measures to control electrostatic hazards?

Key measures include proper grounding and bonding, using conductive or dissipative materials, controlling environmental conditions (like humidity), and implementing safe work practices.

9. Can personal protective equipment (PPE) mitigate electrostatic risks?

Yes, PPE like anti-static footwear, clothing, and gloves can help reduce the risk of static electricity build-up on personnel.

10. What role do environmental factors play in electrostatic hazards?

Environmental factors, particularly humidity, significantly affect the generation and dissipation of static charges. Low humidity environments can increase the risk of electrostatic discharges.

11. What are the Preventive Measures of Electrostatic Hazard?

Static hazards are dealt with by avoiding charge generation, preventing charge accumulation or by removing the charge before there is any possibility of a discharge

  • Avoiding charge generation is likely to require altering the process in some way. In many cases a small change in temperature or humidity may be all that is necessary;
  • Prevention of charge accumulation is often achieved by ensuring all conducting items (including personnel, portable equipment, and fixed plant) are properly grounded. However, this has no effect on insulating equipment and materials. It is also often not appreciated that connecting metal plant to earth may have no effect on the materials being handled inside the plant;
  • In some situations, there will be no alternative but to accept that charge will be generated and begin to accumulate: if the charge is accumulated on the insulating dust, one way forward is to neutralize the charge before it becomes a hazard, ensuring an appropriate relaxation time.

12. How can static electricity be controlled?

Ignition hazards from static electricity can be controlled by the following methods:

  • Removing the ignitable mixture from the area where static electricity could cause an ignition-capable discharge
  • Reducing charge generation, charge accumulation, or both by means of process or product modifications
  • Neutralizing the charges, the primary methods of which are grounding isolated conductors and air ionization
  • Operating outside the flammable range

13. How can conductive materials be bonded and grounded?

It is generally recommended that fixed conductive surfaces and equipment be grounded such that their resistance-to-ground are less than ten (10) ohms (Ω).  However, a resistance-to-ground of as much as 1 x 106 ohms (1 MΩ) can be allowable for rotating and moving conductive parts of mechanical equipment, such as screw feeder screws, blender rotors and conductive probes inside of equipment.  A resistance-to-ground of less than 1 x 106 ohms is generally sufficient to prevent the accumulation of a potentially hazardous level of charge on conductive surfaces and equipment.  The lower value, 10 Ω, is generally recommended for fixed metallic equipment, however, since it is easily achievable, and a higher resistance generally suggests a problem with the grounding system or pathway. The grounding of conductive surfaces and equipment should be checked regularly by measurement as a part of a safety-critical Mechanical Integrity program.

14. How can we control static electric charge on personnel?

The human body is a conductor and subject to charge accumulation when isolated from ground. The maximum stored energy on a human body is generally not expected to exceed 30 mJ.  However, the grounding of personnel is generally recommended when they may be exposed to a flammable atmosphere having a Minimum Ignition Energy (MIE) of less than 100 mJ. Personnel should be grounded such that their resistance-to-ground is less than 1 x 108 ohms (100 MΩ) to prevent the accumulation of a potentially hazardous level of electrostatic charge. However, their resistance should be no lower than 5 x 104 ohms (50 kΩ) in order to protect them from potential electrocution hazards. Steps to prevent charge accumulation include the use of the following:

  • Conductive or static dissipative flooring and footwear
  • Personnel-grounding devices
  • Antistatic or conductive clothing

15. What are the applicable standards for static control in flammable and combustible atmospheres?

NFPA 77 guides on “identifying, evaluating, and controlling static electric hazards to prevent fires and explosions. Other applicable codes and standard includes API RP 2003: Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents and IEC 60079-32-1: Electrostatic Hazards – guidance