Overview
ISO 19438:2023 specifies a standardized multi-pass filtration test for diesel fuel and petrol filters used on internal combustion engines. The procedure uses continuous contaminant injection and an on-line particle counting method at a constant test liquid flow rate to determine a filter’s filtration efficiency, contaminant retention capacity, and differential pressure. The standard applies to filter elements with rated flows between 50 l/h and 800 l/h (with possible agreement-based modification for higher flows).
Key topics and technical requirements
- Test method: Multi-pass recirculation with continuous contaminant injection and online particle counting to monitor upstream/downstream particle counts.
- Measured parameters:
- Filtration efficiency (initial, overall and particle-size-based efficiencies).
- Retained contaminant mass (filter capacity).
- Differential pressure vs. flow characteristics.
- Gravimetric contamination levels and system conductivity (initial and final).
- Test rig components: Separate filter test circuit and contaminant injection circuit, reservoir designs, pumps that do not alter particle size distribution, clean-up filters, turbulent mixing piping, sampling valves for online counting and gravimetric sampling.
- Instrumentation and validation: Accuracy and calibration requirements for particle counters (referencing ISO 11171), validation of dilution/counting systems, contaminant injection, and overall test rig.
- Test materials: Specified test contaminants and test fluid (Annex A), plus guidance on injection flow (recommended 0.25 l/min, with constraints to avoid affecting capacity).
- Reporting and calculations: Detailed methods for calculating efficiencies, filter ratings (µm(c) based on ISO 11171 calibration), injected/non-retained mass, and retained capacity. Annexes include test report templates and example calculations.
Practical applications - who uses ISO 19438:2023
- Fuel filter manufacturers - product development, quality control, and validating filter design performance.
- Automotive OEMs and suppliers - component specification, supplier acceptance testing, and comparative evaluation of diesel/petrol filters.
- Independent test laboratories - accreditation and consistency in filter performance testing using particle counting and gravimetric methods.
- R&D teams - benchmarking filtration efficiency, studying dust-cake effects (Annex D), and optimizing media and constructions.
- Aftermarket and maintenance organizations - performance verification and selection of replacement filters.
Related standards
ISO 19438 references and aligns with other standards used in test setup and measurement, including:
ISO 19438:2023 is a steady-state, laboratory classification test - useful for comparative and design evaluations, but not a direct simulation of transient field operating conditions.