ISO4406:2017 standard for diesel fuel

ISO4406:2017 is the internationally recognised cleanliness code for measuring the solid particulate content of fuel samples and hydraulic fluid. It is also referred to as the ISO cleanliness code. For engines designed to achieve Euro 2, 3, 4 and 5 emission standards, clean fuel is important.

For diesel to be recognised as ‘clean’ the fuel must contain less than 200ppm of dissolved water (as indicated by EN 590) and a particulate cleanliness level of 18/16/13 (as stated by ISO4406:2017). Some engine manufacturers using the latest in high pressure common rail system even require a fuel cleanliness rating of 12/9/6.

But what does ’18/16/13′ mean?

The cleanliness code is made up of three numbers that identify the number of particles that are present in one millilitre of fuel:

For the code quoted above:

• The first number (18) indicates the level of contamination by particles greater than 4 micron
• The second number (16) indicates the level of contamination by particles greater than 6 micron
• The third number (13) indicates the level of contamination by particles greater than 14 micron

For the example given above (18/16/13) the following table shows what each of the range number translates to in terms of particle quantities:

Range Number	Micron Size	Particle Count Range
18	4+	1300 – 2500
16	6+	320 – 640
13	14+	40 – 80

To give you an idea of scale in terms microns:

• Bacteria is 10 micron
• A human hair is 70 micron
• A grain of salt is 100 micron
• The naked eye can detect particles over 40 micron

Specifications

ISO 4406 Cleanliness Table

The table below is an extension of the example given above. It translates what each ISO ‘range number’ means in terms of number of particles found at each micron test.

Range Number	Particle Count Range
>28	2,500,001+
28	2,500,000 – 1,300,001
27	1,300,000 – 640,001
26	640,000 – 320,001
25	320,000 – 160,001
24	160,000 – 80,001
23	80,000 – 40,001
22	40,000 – 20,001
21	20,000 – 10,001
20	10,000 – 5,001
19	5,000  – 2,501
18	2,500 – 1,301
17	1,300 – 641
16	640 – 321
15	320 – 161
14	160 – 81
13	80 – 41
12	40 – 21
11	20 – 11
10	10 – 6
9	5 – 2.6
8	2.5 – 1.4
7	1.3 – 0.65
6	0.64 – 0.33
5	0.32 – 0.17
4	0.16 – 0.09
3	0.08 – 0.05
2	0.04 – 0.03
1	0.02 – 0.02
0	0.01 – 0

For more information on ISO4406:2017

Detailed Information on ISO4406:2017 is not available free-of-charge. It has to be purchased from the International Organization for Standardization (ISO) website. The full text of the standard can be purchased from the ISO Website. For this reason, it cannot be made available for download from IPU’s web site.