Overview
ISO 24218-1:2023 - "Fine bubble technology - Characterization of fine bubbles - Part 1: Evaluation of size and concentration indices by laser diffraction method" specifies a standardized approach to evaluate fine bubble size and concentration using the laser diffraction technique. The standard addresses combined use of number-based size analysis and volume-based size analysis for bimodal and multimodal dispersions, covering a broad size range from tens of nanometers (ultrafine bubbles) to tens of micrometers (microbubbles). It applies to ultrafine bubble dispersions (UFB), microbubble dispersions (MBD) and their mixtures.
Key Topics and Requirements
- Measurement scope: Evaluation of size and concentration indices for samples with multimodal distributions spanning UFB to MB ranges.
- Combined analyses: Specifies using both number-based and volume-based size distributions because number-based analysis emphasizes small bubbles while volume-based analysis emphasizes larger bubbles - both are needed to avoid misinterpretation.
- Laser diffraction method: Instruments must conform to ISO 13320 (particle size analysis - laser diffraction methods). Many instruments and software can generate both normalized number (%) and normalized volume (%) distributions.
- Sample and environment:
- FBDs should be generated with clean equipment, pure water and pure gas (air, N2, O2).
- Air cleanliness, stable ambient temperature and pressure are required to avoid contamination or change in bubble characteristics.
- Sampling and preparation:
- For upper size limits < 10 µm: follow ISO 20298-1 (sampling and sample preparation for UFB).
- For upper size limits > 10 µm: follow ISO 21910-1 (microbubble characterization).
- Data interpretation: Standard explains conversion concepts between number and volume concentrations and highlights the potential for different impressions from number- vs volume-based plots. Annex A provides examples of combined use.
- Reporting: Test report content and essential result presentation are specified.
Applications
ISO 24218-1:2023 is practical for:
- Researchers studying fine bubble behavior and effects (e.g., gas transfer, cleaning efficacy)
- Manufacturers of fine bubble generators and process equipment
- Analytical laboratories performing particle/bubble size characterization
- Industries using fine bubble technology: water and wastewater treatment, aquaculture, agriculture, cleaning, and biomedical applications
The standard helps correlate bubble characteristics (size, number, volume) with functional performance and stability in real-world systems.
Related Standards
- ISO 20480-1 - Fine bubble technology: terminology and general principles
- ISO 20298-1 - Sampling/sample preparation for ultrafine bubble dispersions
- ISO 21910-1 - Characterization of microbubbles (off-line evaluation)
- ISO 13320 - Particle size analysis: laser diffraction methods
For implementation, consult the full ISO 24218-1:2023 text and your national standards body or ISO for licensing and detailed procedures.
Open preview (PDF)Fine bubble technology — Characterization of fine bubbles — Part 1: Evaluation of size and concentration indices by laser diffraction method
