Understanding ISO 16232 and VDA 19.1 Standards for Industrial Parts Cleaning

The ISO 16232 and VDA 19.1 standards are international reference frameworks that define how to measure and ensure the cleanliness of industrial components, particularly in the automotive, aerospace, and medical industries.

Both standards establish methodologies to:

  • Extract contaminant particles
  • Filter and analyze them
  • Classify their size, type, and quantity
  • Compare the results against acceptable limits
Microscopic image of a 400 µm metal particle.

What exactly does the
ISO 16232 standard define?

The ISO 16232 standard covers:

Types of extraction methods (spray, ultrasound, rinsing, combination)
Operating parameters (pressure, duration, temperature)
Filtration procedures
Particle analysis: number, size, type (metallic, non-metallic, fibers)
Interpretation of results according to the type of component

Stages of the cleanliness control process for mechanical parts, including particle analysis and a compliance report.

How to read a cleanliness code (CCC) step by step

On a drawing or in a specification, the cleanliness requirement usually appears as a compact code: the CCC (Component Cleanliness Code). Let’s take a real specification and decode it segment by segment.

SPECIFICATION ON THE DRAWING
CCC =
A1
(
E152
/
F-G103
/
H-I44
/
J-K005
)

Each segment separated by “/” is an independent criterion. The part complies only if it meets all of them.

1 · A
REFERENCE
Per 1,000 cm² of wetted surface
Counts are normalized to surface area, so parts of different sizes can be compared.
2 · E15
50 – 100 µm · LEVEL 15
Max. 32,000 particles
Fine particles: tolerated in large numbers.
3 · F-G10
100 – 200 µm · LEVEL 10
Max. 1,000 particles (F + G combined)
The hyphen groups both classes under a single limit.
4 · H-I4
200 – 600 µm · LEVEL 4
Max. 16 particles (H + I combined)
Particles visible to the naked eye: almost none.
5 · J-K00
600 – 1,500 µm · LEVEL 00
Zero particles
Total ban: a single particle is enough to reject the part.

Step 1: Identify the reference quantity

The letter before the parenthesis tells you what the numbers refer to. Without it, the code cannot be interpreted.

Letter Values are expressed…
Aper 1,000 cm² of wetted surface (our example)
Vper 100 cm³ of wetted volume (circuits, tanks)
Nper part, as an absolute number of particles (not a level)

Step 2: Translate the letters into particle sizes

Each letter is a size class. A hyphen joins adjacent classes that share a single limit: F-G10 means the sum of F + G particles must not exceed level 10. Classes that do not appear in the code (here B, C and D) have no requirement.

no requirement
E15
F-G10
H-I4
J-K00
B
5–15 µm
C
15–25 µm
D
25–50 µm
E
50–100 µm
F
100–150 µm
G
150–200 µm
H
200–400 µm
I
400–600 µm
J
600–1,000 µm
K
1,000–1,500 µm
Hyphen or no hyphen. F-G10 = F + G ≤ 1,000 in total. FG10 (no hyphen) = F ≤ 1,000 and G ≤ 1,000, each one separately.
Watch the edition of the standard. In ISO 16232:2018, class K ends at 1,500 µm and is followed by L, M and N. In earlier editions, K = ≥ 1,000 µm. To ban everything larger, the specification must include L-N00.

Step 3: Convert the level into a maximum number of particles

The number after the letter is not a count: it is a contamination level. The standard defines 26 levels, from 00 to 24; each level roughly doubles the previous one, so a few units of difference mean a lot.

Level 00 is special: it means zero particles, with no tolerance. The highlighted levels are the ones in our example.

Level Particles per 1,000 cm² Example
000J-K
0> 0 to 1—
1> 1 to 2—
2> 2 to 4—
3> 4 to 8—
4> 8 to 16H-I
5> 16 to 32—
6> 32 to 64—
7> 64 to 130—
8> 130 to 250—
9> 250 to 500—
10> 500 to 1,000F-G
11> 1,000 to 2,000—
Level Particles per 1,000 cm² Example
12> 2,000 to 4,000—
13> 4,000 to 8,000—
14> 8,000 to 16,000—
15> 16,000 to 32,000E
16> 32,000 to 64,000—
17> 64,000 to 130,000—
18> 130,000 to 250,000—
19> 250,000 to 500,000—
20> 500,000 to 1,000,000—
21> 1 M to 2 M—
22> 2 M to 4 M—
23> 4 M to 8 M—
24> 8 M to 16 M—

M = million. The upper limit of each level is included (e.g. level 10: more than 500 and up to 1,000 particles).

Step 4: Compare the lab report with the code

A housing with 2,500 cm² of wetted surface is analyzed according to ISO 16232. The lab counts particles on the whole part; since the code is in “A”, the counts are divided by 2.5 to bring them to 1,000 cm².

Criterion Size Counted on the part ÷ 2.5 → per 1,000 cm² Limit Result
B–D5–50 µmreported—no limitInformative
E1550–100 µm41,50016,600≤ 32,000Compliant
F-G10100–200 µm1,820 + 410 = 2,230892≤ 1,000Compliant (borderline)
H-I4200–600 µm27 + 6 = 3313.2≤ 16Compliant
J-K00600–1,500 µm1 + 0 = 1 (640 µm burr)0.40Non-compliant
Part NON-COMPLIANT
Three of the four criteria are met, but a single 640 µm particle is enough to reject the part: level 00 tolerates none, and normalizing to 1,000 cm² changes nothing (0.4 is still greater than 0).
✔ Reference first
A, V or N completely change the reading. Always normalize the counts before comparing.
✔ The level is not a count
Level 10 = up to 1,000 particles; level 4 = up to 16. Each step doubles the limit.
✔ Large particles decide
In practice, rejections almost always come from the large size classes (00 or low levels), not from the fine ones.

How does WashTech help
comply with these standards?

Our systems are designed from the outset to comply with these standards:

Machine design compatible with ISO/VDA controls
Particle separation through fine filtration
Monitoring of critical process parameters (pressure, temperature, timing)
Pre-process validation in the laboratory.

The WashTech Team.

What solutions does
WashTech offer?

At WashTech, we design and manufacture equipment specifically engineered to meet precise cleanliness criteria.

High-precision rotary spray machines
Immersion and ultrasonic systems for extreme criteria
Fine filtration
Pre-process validation with internal testing
Equipment compatible with ISO 16232 / VDA 19.1

Do you have a part that is hard to clean?
Send us a photo or a drawing and we will propose the right solution.

Free advice from our engineers and washing trials with your own parts, in Mexico or France.

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