Overview
ISO/TR 6409:2023 is a technical report from ISO that analyses the technical changes introduced in ISO 5011:2020 (Inlet air cleaning equipment for internal combustion engines and compressors). The report explains how the 2020 revision affects test methods and results for air cleaner systems used on road vehicles, with emphasis on precleaner efficiency, dust injector specifications, filter weighing validation, and the newly included Annex H (“Penetration sensitivity”).
Key topics and technical requirements
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Precleaner efficiency calculation
ISO 5011:2020 revises how precleaner efficiency is calculated by explicitly including the mass gain of the air cleaner housing (in addition to primary, secondary and absolute filter gains). This change closes the gap between “dust removed” and “dust retained in the system” methods and can simplify evaluation where direct measurement of ejected dust is difficult.
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Elimination of collapse and secondary blocking tests
Two seldom-used, time‑consuming tests from ISO 5011:2014 (secondary element rupture under increased differential pressure and the repeated-use secondary blocking test) were removed. Labs can still perform the older tests by agreement or apply substitute collapse/challenge procedures provided in ISO 5011:2020.
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Revised recommended ISO dust injector (Table 1)
The injector guidance now differentiates light‑duty and heavy‑duty injectors with feed-rate ranges per injector (0–5 g/min, 5–26 g/min, >26 g/min). The standard encourages arrays of injectors to avoid clogging and to improve dust distribution. A new dust injector design (Figure B.18) is documented and compared with prior designs using performance maps and shadowgraphy.
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Validation of the absolute filter weighing method
The report describes the requirement to validate the absolute (gravimetric) weighing technique used to quantify dust captured on absolute filters to ensure reliable efficiency measurements.
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Annex H - Penetration sensitivity
Inclusion of Annex H gives examples and guidance on assessing penetration sensitivity, improving precision in reported efficiency.
Practical applications and users
This report is practical for:
- Test laboratories performing ISO 5011 dust capacity and efficiency tests
- Automotive and heavy‑equipment manufacturers and suppliers (air cleaners, precleaners, filter elements)
- R&D and quality teams involved in inlet air system validation
- Certification bodies and procurement engineers specifying performance requirements
Benefits include improved repeatability of precleaner efficiency, reduced test burden by eliminating rarely used procedures, clearer guidance on dust injection setups, and better confidence in gravimetric measurements.
Related standards
- ISO 5011:2020 - Inlet air cleaning equipment for internal combustion engines and compressors (primary normative reference)
- ISO/IEC Directives (development and editorial context)
Keywords: ISO/TR 6409:2023, ISO 5011:2020, precleaner efficiency, dust injector, air cleaner testing, filter weighing validation, penetration sensitivity, collapse test, blocking test.
