Electrostatic adhesion in capsules is a common challenge in pharmaceutical plants. When friction between capsules and insulating surfaces generates electrostatic charge, flow becomes irregular, retention points appear, and productivity drops. Addressing electrostatic adhesion is essential to prevent stoppages, dosing inconsistencies, and quality risks.
How Does Electrostatic Adhesion Occur in the Process?
Even the impact between empty capsules is enough to generate static charge due to their high air-to-weight ratio. In systems equipped with shutoff valves like the Flexivalve, the silicone disc acts as an insulator, intensifying surface electrification and causing adhesion to the elastomer. This effect increases during long campaigns, dry environments, or high transfer speeds.
Main Factors That Increase Adhesion
- Friction between empty capsules during feeding
- Contact with insulating polymeric surfaces
- Process speed and pneumatic turbulence
- Low humidity and lack of charge dissipation
- Materials incompatible with antistatic requirements
These factors create a continuous cycle of charge generation and retention, which requires technical intervention to be controlled.
Impacts of Not Solving Electrostatic Adhesion
Static buildup directly impacts pharmaceutical operations:
Interruptions and Efficiency Loss
Adhesion creates retention points that block flow and cause micro-stoppages, increasing downtime and reducing OEE.
Risk of Contamination and Quality Deviations
Capsules retained in the system may deform or attract unwanted particles, compromising integrity, dosing, and traceability.
Non-Compliance With GMP Standards
Lack of electrostatic control may lead to batch failures, rework, and unfavorable audit outcomes.
Resolving electrostatic adhesion is therefore both a preventive and regulatory action, not just operational.
Solution: Replacing the Silicone Disc With Conductive EPDM
To eliminate adhesion, the applied solution was replacing the Flexivalve’s silicone-coated disc with a conductive EPDM disc designed to dissipate electrostatic charge and maintain a continuous capsule flow.
Why Does Conductive EPDM Perform Better?
- Dissipates charge generated by friction
- Minimizes retention and prolonged surface contact
- Reduces dead spots and adhesion to the elastomer
- Maintains mechanical integrity and sanitary compatibility
- Meets electrical and chemical requirements for the pharmaceutical sector
This modification keeps the entire Flexivalve architecture unchanged, replacing only the disc material.
Implementation Steps
1. Evaluation and Compound Selection
Choosing a conductive EPDM with appropriate resistivity and compliant with FDA, cGMP, and wet-process requirements.
2. Manufacturing the Conductive Disc
Production with controlled thickness, precise tolerances, and uniform conductivity.
3. Testing and Validation
Flow, friction, charge dissipation, and repetitive-cycle testing to ensure performance under real operating conditions.
4. Installation
Replacing only the coated disc, preserving the Flexivalve body and mechanism.
5. Training and Support
Guidance for the maintenance team on inspection, monitoring, and electrostatic control during operation.
Benefits Observed by the Customer
Higher Productivity
Elimination of micro-stoppages and improved capsule-flow stability.
Quality Reliability
Fewer retention points, fewer deformations, and reduced risk of cross-contamination.
Regulatory Compliance
More predictable and traceable processes aligned with GMP expectations.
Lower Operational Costs
Less rework, reduced mechanical wear, and lower product waste.
Comparison Table: Silicone vs. Conductive EPDM
| Criteria | Silicone Disc | Conductive EPDM Disc |
|---|
| Conductivity | Insulating | Dissipative |
| Capsule Adhesion | High | Very Low |
| Pharmaceutical Flow Compatibility | Medium | High |
| Electrostatic Control | Inefficient | Efficient |
| Risk of Micro-Stoppages | High | Minimal |
The application of a conductive EPDM disc has proven to be the most effective solution for eliminating electrostatic adhesion during capsule handling in the Flexivalve. By removing retention points, improving flow behavior, and ensuring stability during continuous operations, the customer achieved higher productivity, improved sanitary performance, and solid regulatory compliance.
See also: Poka Yoke System: Error Prevention in Actuator Assembly | Valves for Interception / Shutoff Applications
Need to Solve Electrostatic Adhesion in Your Line?
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FAQ: Frequently Asked Questions About Electrostatic Adhesion
1. What causes electrostatic adhesion in capsules?
Friction between empty capsules and insulating surfaces, low humidity, and insufficient charge dissipation.
2. Is conductive EPDM compatible with pharmaceutical processes?
Yes. The selected compound meets safety, resistivity, and sanitary-compatibility requirements.
3. Does the modification change the Flexivalve?
No. Only the coated disc is replaced; the body and mechanism remain unchanged.
4. Does the solution fully eliminate adhesion?
In similar applications, it reduces electrostatic retention events by 80–100%.
5. Is it necessary to revalidate the process?
Yes. It is recommended to document the change and perform tests according to cGMP guidelines.
