SubscribeIn an effort to continuously support particle counting in the Aerospace industry, NAS recognised they required a standard for reporting to the new calibration procedure using Medium Test Dust (MTD).
In an effort to continuously support particle counting in the Aerospace industry, NAS recognised they required a standard for reporting to the new calibration procedure using Medium Test Dust (MTD).
So they have introduced a new standard called AS4059 - Aerospace - Cleanliness classification for hydraulic fluids (ISO standard 11218:1993) This standard is an alternative to NAS1638, which was the original standard for reporting using Air Clean Fine Test Dust (ACFTD) as a calibration medium. Below is a chart explaining how the classes are reported.
| Size 1 * Size 2** | >2μm >4μm (c) | >5μm >6μm (c) | >15μm >14μm (c) | >25μm >21μm (c) | >50μm >38μm (c) | >100μm >70μm (c) |
| Size Code | A | B | C | D | E | F |
| Class 12 | 3,200,000 | 1,250,000 | 222,000 | 39,200 | 6,780 | 1,020 |
| Class 11 | 1,600,000 | 623,000 | 111,000 | 19,600 | 3,390 | 512 |
| Class 10 | 800,000 | 311,000 | 55,400 | 9,800 | 1,700 | 256 |
| Class 9 | 400,000 | 156,000 | 27,700 | 4,900 | 848 | 127 |
| Class 8 | 200,000 | 77,900 | 13,900 | 2,450 | 424 | 64 |
| Class 7 | 1,000,00 | 38,900 | 6,920 | 1,220 | 212 | 32 |
| Class 6 | 50,000 | 19,500 | 3,460 | 612 | 106 | 18 |
| Class 5 | 25,000 | 9,730 | 1,730 | 306 | 53 | 8 |
| Class 4 | 12,500 | 4,860 | 864 | 152 | 26 | 4 |
| Class 3 | 6,250 | 2,430 | 432 | 76 | 13 | 2 |
| Class 2 | 3,120 | 1,220 | 217 | 39 | 7 | 1 |
| Class 1 | 1,560 | 609 | 109 | 20 | 4 | 1 |
| Class 0 | 780 | 304 | 54 | 10 | 2 | 0 |
| Class 00 | 390 | 152 | 27 | 5 | 1 | 0 |
| Class 000 | 195 | 76 | 14 | 3 | 1 | 0 |
* Size 1 represents calibration to ACFTD, conforming to ISO4402 principles with particle distribution reported to ISO4406:1996 with the additional 2 micron channel included for reference.
** Size 2 represents calibration to MTD, via a certified primary ISO11171 automatic particle counter using ISO11943 principles, with particle distribution reporting to ISO4406:1999.
To support the new standard, the Parker Laser CM20 now reports AS4059 in all standard particle counters, This can be selected in the same way ISO or NAS is chosen, simply by pressing the “Change Std" button on the handset. Below is an example of how the Laser CM20 reports AS4059 in both ACFTD & MTD.
You will see unlike the original NAS reading it does not show the highest class but all class sizes
with the corresponding number preceding the letter.
Example: 4μ(c) = Size Code A
651763 counts/100ml = Class 10
Therefore the result is 10A.
If you should require additional and specific information relating to this bulletin or any of the Parker Filtration products, please contact Marketing Department Tel: +44 (0) 1924 487000 or Fax +44 (0) 1924 487038.
