By Justin Sheard, Fluke Acoustic Imaging Expert
In the world of cleanroom environments, maintaining strict contamination control is not merely a best practice—it is a regulatory and operational imperative. Whether supporting pharmaceutical manufacturing, semiconductor fabrication, medical device assembly, or aerospace component production, cleanrooms must meet exacting standards for air cleanliness, pressure differentials, and environmental stability.
A pharmaceutical manufacturer operating ISO Class 7 cleanrooms needed to validate tightness following a series of HVAC system upgrades and wall panel replacements.
A critical element of cleanroom validation and maintenance is the ability to detect and resolve air leaks in the cleanroom envelope and associated containment systems. Traditionally, leak detection has relied on pressure-based methods and manual inspections. However, advancements in acoustic imaging technology—specifically the integration of the Fluke SB140 Sound Beacon with Fluke ii905 or ii915 Acoustic Imagers—now enable a non-intrusive, highly efficient, and ISO-compliant method for detecting leaks in cleanroom environments.
Regulatory Framework: ISO 14644-3 and Cleanroom Leak Testing
Among the most influential international standards for cleanrooms is the ISO 14644 series, particularly:
- ISO 14644-1: Classification of air cleanliness by particle concentration.
- ISO 14644-2: Monitoring to demonstrate continued compliance.
- ISO 14644-3: Test methods for confirming cleanroom performance.
ISO 14644-3 outlines procedures for verifying room integrity, including:
- Room tightness (air leakage) tests
- Airflow visualization tests
- HEPA/ULPA filter integrity testing
- Pressure differential verification
These tests are required both during initial validation and routine requalification of cleanrooms. Leak testing, in particular, ensures that the cleanroom envelope is sufficiently sealed to maintain the proper pressure cascade and prevent infiltration of unfiltered or contaminated air.
Why Leak Detection Matters in Cleanrooms
Leakage in cleanrooms can lead to:
- Loss of positive pressure and air cleanliness classification
- Cross-contamination between rooms of differing cleanliness levels
- Reduced efficiency of HVAC and filtration systems
- Risk of product or process contamination, triggering regulatory violations
Consequently, rapid and precise identification of leaks around doors, pass-throughs, utility penetrations, wall panels, and ceiling grids is vital.
Fluke ii905 Acoustic Imager and the Fluke SB140 Sound Beacon
Ultrasound Leak Detection: An Ideal Solution for Cleanroom Environments
Ultrasound-based leak detection has emerged as a powerful tool for cleanroom validation due to its non-intrusive nature, speed, and precision. The Fluke SB140 Sound Beacon, emitting a 40 kHz signal, can be placed inside the cleanroom or an isolated chamber. This ultrasonic frequency propagates efficiently through air and escapes through any imperfections or gaps in the cleanroom envelope.
Using a Fluke ii905 or ii915 Acoustic Imager outside the space, inspectors can visually detect ultrasonic emissions in real time. The imager filters ambient noise and focuses solely on the beacon’s frequency, making it easy to identify leak points in door seals, wall joints, window frames, and service penetrations.
This approach aligns well with the intent and methods outlined in ISO 14644-3 by offering:
- Air leakage localization without the need for pressurization or airflow disruption
- Documentation capability with visual output for validation and audit trails
- Minimal interference with ongoing operations compared to door fan or tracer gas methods
Traditional Leak Testing vs. Acoustic Imaging
| Method | Pressurization Required | Leak Localization | Time Efficiency | Sensitivity | Disruption to Cleanroom |
|---|---|---|---|---|---|
| Blower Door Test | Yes | No | Moderate | Medium | High |
| Smoke Test (Visualization) | Sometimes | Partial/Visual | Moderate | Medium | Medium |
| Tracer Gas (e.g., SF6) | Yes | High (Indirect) | Slow | Very High | High |
| Manual Inspection | No | Limited/Subjective | Slow | Low | Low |
| Ultrasound Imaging (SB140) | No | Direct/Visual w/ onscreen image | Fast | High | Minimal |
Use Case: Cleanroom Integrity Validation in a Pharmaceutical Manufacturing Facility
A pharmaceutical manufacturer operating ISO Class 7 cleanrooms needed to validate tightness following a series of HVAC system upgrades and wall panel replacements. Regulatory compliance under EU GMP Annex 1 and ISO 14644-3 required that room integrity be proven before resuming sterile production.
Instead of performing a full pressurization test or disassembling sections of the cleanroom envelope, the quality assurance team opted to use the Fluke SB140 Sound Beacon placed centrally within the room. With the Fluke ii905 Acoustic Imager operating in Beacon Mode outside the cleanroom, inspectors scanned doors, wall junctions, and HEPA housing seams.
In less than one hour, they identified two compromised gasket areas around a newly installed pass-through chamber and one leak at a utility conduit interface. The team repaired these leaks immediately and repeated the test to confirm integrity. The process provided visual documentation for regulatory auditors and was completed without interrupting adjacent operations.
Benefits of Ultrasound Imaging for Cleanroom Operators
- Non-disruptive: No pressurization or depressurization required; usable in operational cleanrooms
- Speed: Reduces leak testing and verification time from hours to minutes
- Documentation: Generates visual evidence for quality assurance and compliance reports
- Repeatability: Enables consistent requalification over time or after modifications
- Usability: Operable with minimal training and highly portable for use across facilities
Conclusion
As cleanroom regulations become more stringent and contamination control more critical, the ability to detect air leaks quickly and accurately is increasingly essential. The combination of the Fluke SB140 Sound Beacon and acoustic imaging technology offers a powerful alternative to traditional leak testing methods. By aligning with ISO 14644-3 requirements and delivering speed, precision, and minimal disruption, ultrasound leak detection has become an invaluable tool for cleanroom engineers, quality managers, and validation teams.
Whether used during initial commissioning, routine requalification, or post-modification inspection, acoustic imaging represents a smarter, cleaner, and more effective path to maintaining cleanroom integrity and regulatory compliance.
About the Author
Justin Sheard is an accomplished product development leader specializing in thermal and acoustic imaging technology, particularly in preventive maintenance applications. With multiple patents and published works, Justin is a thought leader in the industry. He is dedicated to shaping the future of preventive maintenance through innovative imaging solutions that help maintenance professionals prevent unplanned downtime and improve operational efficiency. Connect with Justin on LinkedIn.