Overview
This case study outlines an electrostatic (static) risk assessment carried out by OTECSA Consulting for a UK manufacturer considering bringing flammable solvent drum filling operations in-house.
The proposal involved filling 200 L blue HDPE drums within an existing indoor hazardous area. While commercially attractive, the use of non-conductive containers introduced significant electrostatic ignition risks that required detailed evaluation.
Project Background and Electrostatic Risk Assessment Context
- Client: UK manufacturer of flammable liquids (confidential)
- Operation: In-house filling of 200 L HDPE drums
- Location: Indoor filling area, within a currently ATEX zoned area
- Regulatory context: Existing DSEAR and hazardous area classification identified as ATEX Zone 1 and Zone 2 around the operation
The project built on prior DSEAR and Hazardous Area Classification work and required a focused electrostatic risk assessment to determine whether the proposed change could be justified from a safety and compliance perspective.
The Challenge
HDPE drums are widely used due to their durability and cost-effectiveness. However, they are electrically insulating, making them unsuitable for use in areas where flammable atmospheres may be present.
During filling operations:
- Static charge can be generated through liquid movement and splash filling
- Charge can accumulate on insulating surfaces
- A discharge in the presence of flammable vapour may result in ignition
The key challenge was determining whether this operation could be safely implemented, and if not, what measures would be required to reduce risk.
Electrostatic Risk Assessment Approach
OTECSA carried out a structured electrostatic risk assessment, including:
- Review of existing DSEAR and hazardous area classification
- Inspection of current filling systems and proposed modifications
- Interpretation of IEC TS 60079-32-1 guidance
- Evaluation of site-specific operating conditions
- Development of a technical guidance note outlining compliance and risk reduction measures
Key Findings from the Electrostatic Risk Assessment
Insulating Containers
Standard HDPE drums cannot be effectively earthed. Guidance discourages their use in hazardous areas where flammable atmospheres may occur.
Static Charge Generation
Filling processes, particularly splash filling and high flow rates, increase the likelihood of electrostatic charge build-up.
Ignition Risk
A discharge from a charged surface could ignite a flammable vapour/air mixture, particularly within Zone 1 or Zone 2 environments.
Compliance Challenges
Even with controls, the proposed operation would not align with best practice and could be difficult to justify as fully compliant.
Risk Reduction Strategy
OTECSA advised that if the client chose to proceed, a layered approach to risk reduction would be required.
This included a combination of engineering and procedural controls designed to:
- Minimise charge generation
- Prevent charge accumulation
- Reduce the likelihood of ignition
Multiple safeguards would need to be implemented together to achieve a tolerable level of risk.
Practical Considerations
From a best practice perspective, conductive or static-dissipative containers would be preferred, as they can be earthed and align with electrostatic safety guidance.
However, these options were considered commercially impractical by the client.
The recommended controls would reduce risk but introduce:
- Increased operational complexity
- Longer filling times
- Additional maintenance and verification requirements
This required a balance between commercial drivers and safety expectations.
Outcome and Value Delivered
- A clear independent position on compliance with electrostatic guidance
- Identification of key hazards and limitations of the proposed design
- Practical, layered recommendations to reduce ignition risk
- Support for informed decision-making based on risk, cost, and compliance
This project demonstrates the value of a robust electrostatic risk assessment in bridging the gap between regulatory expectations and real-world operational constraints.
Expert Insight
“The guidance is clear: using insulating containers in a hazardous filling area is not recommended. If the client chooses to proceed, a combination of engineering and procedural controls is needed to reduce risk, but the decision and residual risk acceptance remain theirs.”
— David Fox, Senior Process Safety Consultant, OTECSA
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