Overview
ISO 21256-3:2021 - Fine bubble technology: Test method for cleaning hard flooring surfaces defines a repeatable laboratory method to evaluate the cleaning performance of fine bubble solutions versus alternative cleaning fluids (another fine bubble solution, municipal tap water, or a commercial cleaner). The standard describes apparatus modifications, a standardized test soil and deposition method, test-piece preparation, measurement procedures and a cleaning-index calculation to quantify soil removal.
Key topics and technical requirements
- Test principle: Measure mass loss of residual contaminant to calculate a cleaning index (E = (Ms − Mc) / (Ms − Mi), where Mi = initial mass, Ms = mass with soil, Mc = mass after cleaning).
- Apparatus: Uses a modified reciprocating scrub test machine with a hydraulic atomizing nozzle (hollow-cone spray, ~70° angle, ~1 mm orifice). Nozzle travel and spray geometry are specified to ensure consistent coverage.
- Flow, pressure and temperature: Typical settings include outlet flow 0.23 ± 0.02 L/min, supply tap-water flow ~0.45 ± 0.05 L/min, and nozzle pressure 200 kPa ± 10 kPa. Cleaning liquid temperature: 20 °C to 26 °C ± 1 °C.
- Test pieces and soil: Test tiles: uncoated vinyl composite, 300 mm × 150 mm (±10 mm). Surface soil density target 28 mg/cm². Test soil formulation (Annex A) lists specific ingredients (mineral/hydraulic oils, clays, red iron oxide, wood flour) and deposition using a doctor blade/stencil method.
- Measurement accuracy: Mass determined with resolution 0.01 g or better; cleaned tiles dried to constant mass (or ≥3 h at ≈45 °C) before weighing.
- Test limitations: Not suitable when contaminant is excessively applied-mechanism of cleaning changes and results are not differentiating.
Applications and practical value
- Provides a standardized, comparable laboratory method to:
- Quantify and compare cleaning efficacy of fine bubble generators, water-only systems and chemical cleaners on hard floors.
- Support product development and performance claims for industrial or commercial cleaning equipment (e.g., walk-behind floor cleaners, automated scrubbers).
- Reduce chemical usage by validating fine bubble solutions as alternatives, contributing to sustainability goals (reduced chemicals, lower energy/carbon footprint).
- Useful in R&D, quality control, third‑party testing, procurement specifications and regulatory/market-claim substantiation.
Who should use this standard
- Manufacturers of fine bubble generators and cleaning equipment
- Flooring manufacturers and materials test labs
- Building services, janitorial product developers, and independent testing laboratories
- Procurement teams and regulators seeking objective performance metrics
Related standards
- ISO 20480-1 - Fine bubble technology: terminology and general principles for usage and measurement (normative reference).
- See other parts of the ISO 21256 series for broader fine bubble technology guidance.