ISO 12500-1:2007

Overview

ISO 12500-1:2007 - "Filters for compressed air - Test methods - Part 1: Oil aerosols" specifies the test layout and procedures for evaluating coalescing filters used in compressed-air systems. The standard defines how to measure a filter’s ability to remove oil aerosols and the associated pressure drop, and presents one method of reporting filter performance as outlet oil aerosol concentration (mg/m³) under defined rating parameters.

Key topics and technical requirements

• Test layout and equipment: Typical test rig arrangement (air supply, aerosol generator, flow control, sensing points, filter under test) and sampling points are defined.
• Standard rating parameters: Reference conditions include inlet temperature (~20 °C), test pressure (commonly 700 kPa / 7 bar(e)), rated flow (100% of manufacturer’s rated flow) and inlet oil-aerosol challenge concentration (documented test values).
• Aerosol challenge: Poly-disperse oil aerosol with mean particle size ~0.15–0.40 µm (by particle count). Care to ensure aerosols, not wall flow, enter the filter.
• Flow and Reynolds number: Tests use the manufacturer’s maximum rated continuous flow; minimum Reynolds number in the inlet pipe shall be 4 000 to maintain turbulent flow.
• Conditioning and wet pressure drop: Filters must reach equilibrium (liquid oil visible in housing and pressure-drop change <1%/hr) before measurement of wet pressure drop at rated flow.
• Measurement of oil concentration: Per ISO 8573-2 or using a validated white-light-scattering photometer (ISO 14644-3 Annex C). Sampling must be full-flow or iso-kinetic as required.
• Repeatability and reporting: At least three samples of a model tested; three repeats per element averaged. Test reports must state model numbers, mean outlet concentration, pressure drop, inlet challenge concentration and confirm testing per ISO 12500-1.
• Uncertainty: Guidance on estimating measurement uncertainty and confidence limits (95% typical) is provided.

Applications and practical value

• Compare and rate compressed-air coalescing filters for oil removal efficiency.
• Define procurement and specification requirements for industrial compressed-air systems (manufacturing, food & beverage, pharmaceutical, automotive).
• Support filter manufacturers, independent test laboratories, compressor OEMs and maintenance/quality teams in demonstrating compliance and selecting filters that minimize oil contamination and system pressure loss.
• Useful for specifying filtration in systems where downstream pneumatic equipment or processes are sensitive to oil aerosols.

Related standards

• ISO 12500-2 (Oil vapours) and ISO 12500-3 (Particulates)
• ISO 8573-1 / ISO 8573-2 (Compressed air purity and oil-aerosol test methods)
• ISO 14644-3 (Cleanrooms - test methods, photometer guidance)
• ISO 7183 (Compressed-air dryers - test methods)

Keywords: ISO 12500-1, filters for compressed air, oil aerosols, coalescing filters, test methods, pressure drop, aerosol concentration, ISO 8573-2, compressed-air filtration.