Filtertechnik
1 Central Park, Lenton Lane, Nottingham, NG7 2NR
Tel:
+44 (0)115 9003 600
Email:
Fax:
+44 (0)115 986 8875
Registered in England No: 03969985 VAT No: 760 821 731
Certification No. UK002838
Page 12 of 15
Appendix A
–
Achieving ISO Cleanliness Codes
Filtertechnik has a wide range of elements available to effectively achieve the required cleanliness
level for the intended system. Maintaining the fluid at the required cleanliness level is a cost-
effective way of extending the service life of system components. The tables below can be used to
determine the required micron rating of the filter to achieve the desired cleanliness code,
understand the ISO 4406 contamination scale, conversion between the various cleanliness standards
and understanding how the ISO 4406 scale relates to the NAS contamination scale.
Number of Particles per 1ml
of Fluid
ISO
Scale
Number
More Than
Up to and
Including
1,300,000
2,500,000
28
640,000
1,300,000
27
320,000
640,000
26
160,000
320,000
25
80,000
160,000
24
40,000
80,000
23
20,000
40,000
22
10,000
20,000
21
5,000
10,000
20
2,500
5,000
19
1,300
2,500
18
640
1,300
17
320
640
16
160
320
15
80
160
14
40
80
13
20
40
12
10
20
11
5
10
10
2.5
5
9
1.3
2.5
8
0.64
1.3
7
0.32
0.64
6
0.16
0.32
5
0.08
0.16
4
0.04
0.08
3
0.02
0.04
2
0.01
0.02
1
0.00
0.01
0
ISO 4406 Contamination Scale
Desired Cleanliness
Level (ISO Code)
Recommended
Filtration Media
20/18/15
–
19/17/14
25 µm
19/17/14
–
18/16/13
10 µm
18/16/13
–
15/13/10
5 µm
15/13/10
–
14/12/9
3 µm
14/12/9
–
13/11/8
1 µm
Filter Media Selection Guide
