Cleanliness tester rating

The "rating" of the cleanliness tester usually involves two dimensions: the certification rating of the instrument performance and the rating of the cleanliness of the tested object. The following is a detailed analysis from these two aspects:

1. Certification rating of instrument performance

The reliability of the cleanliness tester must be certified by an authority to ensure that the test data meets international standards. Common certifications include:

ISO standard compliance

Compliance with ISO 16232 （Particle Count Cleanliness Test Standard） indicates that the instrument can accurately detect particles in a specific size range.

ISO 4406 certification is applied to hydraulic oil cleanliness testers to verify their particle count accuracy.

Industry standard certification

VDA 19 （German Automotive Industry Standard） : Certified instruments are required to meet the cleanliness test requirements of automotive engine components.

NASA-STD-6001: Suitable for aerospace applications, ensuring that instruments can detect molecular contaminants.

Calibration and traceability

It is regularly calibrated by a third-party laboratory （such as the National Metrology Institute） and issues a traceability certificate to ensure the legal validity of the test results.

2. Cleanliness rating of the tested object

Different industries develop cleanliness levels according to pollution tolerance, and common standards are as follows:

1）. Particle pollution level

ISO 4406 （Hydraulic Fluids）

Grading by particle size, such as 18/15/12 means that in each milliliter of hydraulic oil:

≥4μm particles ≤1800

≥6μm ≤1500 particles

≥14μm ≤1200 particles

ISO 16232 （Mechanical Parts）

Grade by number of particles per unit area, such as:

Grade A: ≤200μm Number of particles ≤50 /cm²

Grade B: Allow a small number of large particles （such as ≤500μm）

VDA 19 （Automotive Engine）

Cleanliness levels based on key component functions, such as:

Cleanliness Class 1: Fuel system （particle number ≤100 /cm²）

Cleanliness Class 3: Cylinder block （higher particle count allowed）

2）. Chemical residue level

Electronics Manufacturing （IPC standard）

Ion pollution level: such as ≤1.0μg NaCl/cm² （to avoid electrochemical corrosion）。

Organic residue grade: For example, the residual flux after welding should be less than 0.5% area coverage.

Medical Equipment （ISO 15883）

Protein residue: The residual amount of the instrument after cleaning is less than 1μg/cm².

Microbial contamination: Colony number ≤10³ CFU/ piece.

3）. Other special ratings

Aerospace （NASA-STD-6001）

Molecular cleanliness: Detection of volatile organic compounds （VOCs） residue in vacuum components, ≤0.1% mass fraction.

Food Processing （HACCP）

Microbial cleanliness: the number of colonies on the surface of the equipment is ≤10 CFU/cm².

3. Cleanliness rating process

Test method selection

Particle contamination: optical method, laser scattering method or vacuum adsorption method.

Chemical residue: Extraction-chromatography （e.g. HPLC, GC-MS）。

Microbial contamination: contact dish or ATP bioluminescence.

Data analysis

Count the number of particles, concentration of pollutants, or number of microorganisms per unit area/volume.

Compare standard limits （such as ISO 4406 codes or VDA 19 forms）。

Rank decision

If the detection value ≤ standard value → judged as "in line with level X".

If exceeded → need to repeat the test or adjust the cleaning process.

Iv. Industry differences and precautions

Automotive vs Electronics: The automotive industry focuses more on the impact of large particles （≥50μm） on mechanical wear, while the electronics industry focuses on the risk of short circuits caused by small particles （≤10μm）。

Dynamic contamination monitoring: Some industries, such as semiconductors, require real-time online monitoring rather than laboratory sampling.

Through scientific ratings, companies can accurately control pollution risks, ensure product compliance with regulatory requirements and improve reliability.

2025-03-20 14:32