Overview
ISO 12500-3:2009 - Filters for compressed air - Test methods - Part 3: Particulates specifies test layouts and procedures to determine the solid particulate removal efficiency by particle size for filters used in compressed air systems. It defines two particle-size ranges - fine (0.01 µm to <5.0 µm) and coarse (≥5.0 µm to ≤40 µm) - and recommends measurement methods and instruments appropriate to each. Tests are performed as type-tests meant to represent a range of filter elements and include requirements for aerosol generation, sampling, and data reporting.
Key topics and technical requirements
- Particle size ranges: Fine (0.01 µm–<5 µm) and coarse (5 µm–40 µm).
- Measurement methods: Recommended instruments include LPC (laser particle counter), OAS (optical aerosol spectrometer), and mobility/condensation systems such as SMPS, DMA, CPC/CNC depending on particle size and concentration.
- Aerosol challenge: Fine-particle tests use NaCl, KCl or DEHS aerosols (per EN 1822 series); coarse tests use ISO 12103-1 A4 (Arizona) test dust prepared and dried to specified conditions.
- Sampling & detection: Fine-particle sampling follows ISO 8573-4; coarse-particle methods are specified in ISO 12500-3. Correct for counting-efficiency differences when using multiple particle counters.
- Operational conditions: Reference conditions are 20 °C and 100 kPa (1 bar); preferred test pressure is 700 kPa(e) [7 bar(e)], but alternative pressures are allowed if equivalent flow velocity is maintained. Turbulent flow (Reynolds number > 4 000) is required for representative sampling.
- Test procedure: Minimum of three complete test cycles with a new filter per run; record pressure drop at start and end; results typically reported as efficiency vs particle size curves and include measurement uncertainty.
- Most Penetrating Particle Size (MPPS): Locate MPPS using monodisperse aerosols for fine-filter characterization.
Applications and who uses it
ISO 12500-3 is used by:
- Filter manufacturers for type-testing and product specification.
- Independent test laboratories performing standardized efficiency measurements.
- Compressed air system designers and maintenance engineers selecting filters to meet required purity classes (e.g., ISO 8573 series).
- Quality, procurement, and compliance teams in industries such as pharmaceuticals, food & beverage, electronics, and general manufacturing where particle-free compressed air is critical.
Practical applications include selecting the right particulate filter for process lines, verifying filter performance claims, and ensuring compatibility with system pressure, flow and required compressed air purity.
Related standards
