Filtertechnik
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+44 (0)115 9003 600
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Fax:
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Registered in England No: 03969985 VAT No: 760 821 731
Certification No. UK002838
Page 14 of 15
Conversion between Standards
ISO 4406 Code
4µm / 6µm / 14µm
Mil Std.
NAS 1638
Mil Std.
1246A
ACFTD Gravimetric
Level mg/L
SAE Level
21/19/16
10
20/18/15
9
6
19/17/14
8
300
5
18/16/13
7
1
4
17/15/12
6
3
16/14/12
200
16/14/11
5
2
15/13/10
4
0.1
1
14/12/9
3
0
13/11/8
2
12/10/8
100
10/10/7
1
12/10/6
0.01
11/9/6
Cleanliness Standards Conversion
Equivalent ISO
4406 Code
(approx.)
NAS
Code
Size Range in Microns (µm)
5-15
15-25
25-50
50-100
>100
-
00
125
22
4
1
0
-
0
250
44
8
2
0
10/12/7
1
500
89
16
3
1
13/11/8
2
1,000
178
32
6
1
14/12/9
3
2,000
356
63
11
2
15/13/10
4
4,000
712
126
22
4
16/14/11
5
8,000
1,425
253
45
8
17/15/12
6
16,000
2,850
506
90
16
18/16/13
7
32,000
5,700
1,012
190
32
19/17/14
8
64,000
11,400
2,025
360
64
20/18/15
9
128,000
22,800
4,050
720
128
21/19/16
10
256,000
45,600
8,100
1,440
256
22/20/17
11
512,000
91,200
16,200
2,880
512
23/21/18
12
1,024,000
182,400
32,400
5,760
1,020
ISO 4406 vs NAS 1638 Contamination
