🚗 Technical Cleanliness (ISO 16232)
In short
Technical cleanliness inspection of components and systems of road vehicles according to ISO 16232:2018: requirements for applying and documenting methods for determining particulate contamination — extraction from the component, analysis filtration and particle analysis. The test is performed according to ISO 16232:2018; Declining test: six identical extraction steps on the same component; declining criterion 10 % (3.38, 3.41). The procedure comprises 7 steps; it is used for: Initial inspection and evaluation of the cleanliness of functionally relevant components and systems of road vehicles, Inspection of incoming and outgoing components in the supply chain, Control and monitoring of processes relevant to cleanliness — cleaning, surface treatment and assembly.
At a glance
- Standard: ISO 16232:2018
- Category: Automotive
- Procedure steps: 7
- Declining test: six identical extraction steps on the same component; declining criterion 10 % (3.38, 3.41)
- Double inspection: two identical steps confirming qualified parameters; criterion 30 % (3.41)
- Blank level: not more than 10 % of the required or expected cleanliness value (3.13)
Overview
STATUS (as of 02.11.2026). ISO 16232:2018 (published 12.12.2018) replaced the entire ISO 16232-1 to -10 series of 2007, revised and consolidated into a single document; in the ISO catalogue the standard is at stage 90.92 (“to be revised”). The standard has not been adopted as a PN — the PKN search for “ISO 16232” returns only PN-EN 16232, which has a different subject (the same query for “ISO 9227” returns PN-EN ISO 9227). It was prepared by committee ISO/TC 22/SC 34 (road vehicles — propulsion, powertrain and powertrain fluids). According to a publication of April 2026, the content of the new edition of the VDA 19.1 guideline is to be transferred to ISO 16232 and work on this is under way.
SCOPE (Clause 1). The standard specifies requirements for applying and documenting methods for determining particulate contamination on functionally relevant components and systems of road vehicles (cleanliness inspection). A cleanliness inspection is the basis of an assessment of technical cleanliness, e.g. for initial inspection and evaluation, for inspection of incoming and outgoing components and for control of processes relevant to cleanliness (cleaning, surface treatment, assembly). The standard does not cover filmy contamination (greases, oils), non-quantifiable methods (visual assessment, wipe test) or the characterization of operating fluids (fuel, oils, coolants, brake fluid), and does not set cleanliness limit values — guidance for deriving them is given in Annex H.
INSPECTION PRINCIPLES (Clauses 5–9). Contaminants are transferred from the controlled surface or volume of the component into a test fluid (liquid or air extraction), the entire liquid after extraction is filtered through an analysis filter, and the particles on the filter are analysed. The analysis has a standard, an extended and a shortened variant (9.2–9.4); the analysis balance is defined as a balance with a resolution of 10⁻⁴ g to 10⁻⁶ g, and the automatic particle counter as a counter working on the light extinction principle. The result is expressed, among other things, by the component cleanliness code (CCC) — an alphanumeric expression of the cleanliness level described by the particle size distribution. A fibre is a structure with a ratio of stretched length to maximum inner circle diameter greater than 20 and a width not greater than 50 µm.
QUALIFICATION AND BLANK LEVEL (Clause 6, Annex B). The efficacy of the extraction parameters is checked by a declining test: the extraction step is repeated six times on the same component in an identical manner, and the declining value — the quotient of the result of the given step and the sum of all results so far (in percent) — is compared with the declining criterion of 10 %. In a double inspection (two identical steps confirming qualified parameters) the criterion is 30 %. The blank level — contamination from sources other than the component (reagents, glassware, preparation, environment), determined under the same conditions without the component — must not exceed 10 % of the required or expected cleanliness value.
ANNEXES. Selection of extraction and analysis methods (A), qualification tests and blank level (B, normative), recovery of test particles (C), extraction (D, normative), filtration (E), analysis methods (F, normative), documentation (G), cleanliness specification (H), interpretation and reaction (I), staff training (J), work safety and protection of the environment (K), summary of updates (L).
WHAT WE DO NOT GIVE HERE. Extraction parameters (pressures, flow rates, frequencies and times), test fluids, analysis filters (type and pore size), particle size classes and the structure of the cleanliness code, microscope analysis settings and requirements for rooms — they are in Clauses 5–12 and the annexes of the standard, beyond the available text (which reaches the definitions).
Method principle
Particulate contaminants are transferred from the controlled surface or volume of the component into a test fluid by a qualified extraction method (liquid or air), the entire liquid is filtered through an analysis filter, and the particles retained on the filter are analysed — gravimetrically, microscopically or by other methods from Annex F. The efficacy of the extraction is confirmed by the declining test (six identical steps, criterion 10 %) and its reliability by a blank level not greater than 10 % of the required or expected cleanliness value. The result is given, among other things, as the component cleanliness code (CCC).
Applications
- Initial inspection and evaluation of the cleanliness of functionally relevant components and systems of road vehicles
- Inspection of incoming and outgoing components in the supply chain
- Control and monitoring of processes relevant to cleanliness — cleaning, surface treatment and assembly
- Standardised expression of cleanliness specifications and results (component cleanliness code CCC)
- The standard does not cover filmy contamination, non-quantifiable methods (visual assessment, wiping) or the characterization of operating fluids
Key parameters
| Parameter | Value |
|---|---|
| Declining test | six identical extraction steps on the same component; declining criterion 10 % (3.38, 3.41) |
| Double inspection | two identical steps confirming qualified parameters; criterion 30 % (3.41) |
| Blank level | not more than 10 % of the required or expected cleanliness value (3.13) |
| Analysis balance | resolution from 10⁻⁴ g to 10⁻⁶ g (3.6) |
| Fibre | ratio of stretched length to maximum inner circle diameter > 20, width ≤ 50 µm (3.53) |
| Analysis | standard, extended or shortened (9.2–9.4) |
Standard
- Standard number
- ISO 16232:2018
- Title (PL)
- Pojazdy drogowe — Czystość komponentów i systemów (tłumaczenie robocze — normy nie wprowadzono do PN)
- Title (EN)
- Road vehicles — Cleanliness of components and systems
Step-by-step procedure
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Choice of method and parameters
Choose the extraction, filtration and analysis methods for the component and the requirements (Clause 5, Annex A); the controlled surface or volume is set by the cleanliness specification.
-
Blank level
Carry out the entire procedure under the same conditions without the component; the blank level must not exceed 10 % of the required or expected cleanliness value.
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Declining test
Qualify the extraction parameters: repeat the extraction step six times on the same component in an identical manner and compare the declining value with the 10 % criterion.
-
Extraction
Transfer the contaminants from the controlled surface or volume into the test fluid with the qualified parameters (Clause 7, Annex D).
-
Analysis filtration
Filter the entire liquid after extraction through the analysis filter and check the filter occupancy (Clause 8).
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Analysis
Analyse the particles on the filter — standard, extended or shortened analysis (Clause 9, Annex F).
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Documentation
Document the component, preparation, extraction, filtration, analysis and results, including the component cleanliness code (Clause 10, Annex G).
Required equipment and apparatus
| Equipment | Example | Indicative price |
|---|---|---|
| Extraction setup | for liquid or air extraction, with collection equipment for all the liquid draining from the component (Clause 7) | — |
| Analysis filtration set | filter housing with upper and lower section, inlet, outlet and supporting grid; meshed or foamed analysis filter (3.7, 3.55) | — |
| Analysis balance | resolution from 10⁻⁴ g to 10⁻⁶ g (3.6) | — |
| Particle analysis system | light microscope, scanning electron microscope with back-scattered electron detector and EDX analysis, or an automatic particle counter working on the light extinction principle (3.10, 3.11, 3.43, Annex F) | — |
Reagents, media and consumables
| Reagent | CAS | Details |
|---|---|---|
| Test fluid | — | liquid or air for extraction, compatible with the component and the equipment; selected according to Clause 7 and Annex A of the standard |
Health and safety (OHS)
- The standard warns that its use can involve hazardous materials, operations and equipment and that safety practices are established by the user (Clause 1); Annex K is devoted to work safety and protection of the environment, but we did not have its text
Frequently asked questions
Which standard describes this test?
The test is performed according to ISO 16232:2018 — “Road vehicles — Cleanliness of components and systems”.
How does this method work?
Particulate contaminants are transferred from the controlled surface or volume of the component into a test fluid by a qualified extraction method (liquid or air), the entire liquid is filtered through an analysis filter, and the particles retained on the filter are analysed — gravimetrically, microscopically or by other methods from Annex F. The efficacy of the extraction is confirmed by the declining test (six identical steps, criterion 10 %) and its reliability by a blank level not greater than 10 % of the required or expected cleanliness value.
What is the measuring range and accuracy?
Declining test: six identical extraction steps on the same component; declining criterion 10 % (3.38, 3.41); Double inspection: two identical steps confirming qualified parameters; criterion 30 % (3.41); Blank level: not more than 10 % of the required or expected cleanliness value (3.13); Analysis balance: resolution from 10⁻⁴ g to 10⁻⁶ g (3.6).
How long does the test take?
The procedure comprises 7 steps. The standard does not give a duration for every stage — the laboratory's own procedure decides.
What equipment is required?
Extraction setup, Analysis filtration set, Analysis balance, Particle analysis system.
Where is this test used?
Initial inspection and evaluation of the cleanliness of functionally relevant components and systems of road vehicles; Inspection of incoming and outgoing components in the supply chain; Control and monitoring of processes relevant to cleanliness — cleaning, surface treatment and assembly; Standardised expression of cleanliness specifications and results (component cleanliness code CCC); The standard does not cover filmy contamination, non-quantifiable methods (visual assessment, wiping) or the characterization of operating fluids.
What safety precautions apply?
The standard warns that its use can involve hazardous materials, operations and equipment and that safety practices are established by the user (Clause 1); Annex K is devoted to work safety and protection of the environment, but we did not have its text.
Which laboratory can perform this test?
The test is performed by laboratories accredited to ISO/IEC 17025. On LabCoda you can find them by the standard number ISO 16232.