FluidControl Unit - FCU 1000 Series
HYDAC Filtertechnik GmbH
en
Page 56
BeWa_FCU1000_3371346a_en.doc
2007-12-04
15
ISO 4406 / SAE AS 4059 and NAS 1638 Classes
15.1 ISO
4406:1999
In ISO 4406:1999, particle counts are determined cumulatively, i.e. > 4 µm(c), >6 µm(c) and
>14 µm(c) (manually by filtering the fluid through an analysis membrane or automatically
using particle counters) and allocated to measurement references.
The goal of allocating particle counts to references is to facilitate the assessment of fluid
cleanliness ratings.
In 1999 the "old" ISO 4406:1987 was revised and the size ranges of the particle sizes
undergoing analysis redefined. The counting method and calibration were also changed.
This is important for the user in his everyday work: even though the measurement references
of the particles undergoing analysis have changed, the cleanliness code will change only in
individual cases. When drafting the "new" ISO 4406:1999 it was ensured that not all the
existing cleanliness provisions for systems had to be changed.
15.1.1 ISO 4406 table
Allocation of particle counts to cleanliness classes:
Particle count / 100 ml
Particle count / 100 ml
Class
More than
Up to (and including)
Class
More than
Up to (and including)
0
0 1
15
16,000 32,000
1
1
2
16
32,000
64,000
2
2 4
17
64,000 130,000
3
4
8
18
130,000
250,000
4
8 16
19
250,000 500,000
5
16
32
20
500,000
1,000,000
6
32 64
21
1,000,000 2,000,000
7
64
130
22
2,000,000
4,000,000
8
130 250
23
4,000,000 8,000,000
9
250
500
24
8,000,000
16,000,000
10
500 1,000
25
16,000,000 32,000,000
11
1,000
2,000
26
32,000,000
64,000,000
12
2,000 4,000
27
64,000,000 130,000,000
13
4,000
8,000
28
130,000,000
250,000,000
14
8,000 16,000
