TECHNICAL REFERENCE
Cleanliness Level Correlation Table Conversion of cleanliness specifications to filter performance is not an exact science because the contamination level in a hydraulic system is a function of the ingression and generation rate as well as the filter performance. Factors That Affect Cleanliness Levels in a Hydraulic System • Abrasive wear in space between adjacent moving surfaces of components. • Erosive wear at component edges or direction changes where there is high fluid velocity. • Fatigue wear by particles trapped between moving surfaces. Identification of the Most Sensitive Component • Required cleanliness level is dominated by the component with smallest clearances and/or highest loading on the lubricating film. • Best source for determining this level is the specification published by the component manufacturer. • Higher pressures reduce component life, unless contamination level is decreased accordingly. • Operating at half the rated pressure of component will
ISO
Particles
ISO FTD*
Mil Std 1236A
NAS 1638
Code
Per Milliliter >10 microns
Gravimetric Level (mg/l)
SAE Level
(1967)
(1964)
(1963)
30/26/23 29/25/23 26/25/20 23/21/18 2220/18 22/20/17 21/20/17 21/19/16 20/18/15 19/17/14 18/16/13 17/15/12 16/14/12 16/14/10 15/13/10 14/12/9 13/11/8 12/10/8 12/10/7 11/10/6 11/9/6 10/8/5
140,000 85,000 14,000
1000
1000
100
700
4,500 2,400 2,300 1,400 1,200
12
500
11
10
10
580 280 140
9 8 7 6 5 4 3 2
6 5 4 3 2 1 0
300
1
70 40 35 14
200
0.1
9 5 3
100
2.3 1.4 1.2 0.6 0.3
1
0.01
0 0
9/7/5 8/6/3 7/5/2 6/2/.8
50
0.14 0.04 0.01
0.001
25 10
increase its life by more than four times. • Percent of operating time at maximum pressure depends on individual machines and application.
* SAE Fine Test Dust – ISO approved test and calibration contaminant. Source: Milwaukee School of Engineering Seminar, Contamination & Filtration of Hydraulic Systems
Cleanliness Code ISO 4406: 1999
Suggested Efficiency ISO 16889
Suggested media
System type
15/13/10
servo-valves for pressure >20MPa, laboratory & aerospace
ß 2 m(c) = 200 ß 2 m(c) = 200 ß 5 m(c) = 200 ß 7 m(c) = 200 ß 7 m(c) = 200 ß 10 m(c) = 200 ß 10 m(c) = 200 ß 12 m(c) = 200 ß 12 m(c) = 200 ß15 m(c) = 200 ß 15 m(c) = 200 ß 20 m(c) = 200 ß 25 m(c) = 200 ß 25 m(c) = 200 ß 10 m(c) = 2 ß 40 m(c) = 200 ß 23 m(c) = 2
/00
/00 XP5 XP5
14/16/11
high perf. & high press. long life components, i.e. small gearbox
17/15/12
i.e. servo-valves, general power transmission gearbox
high quality reliable, general purpose mach., vane & piston pumps, prop. valves, large gearbox
XP5 XP10
18/16/13
19/17/14
gear pumps
XP10
20/18/15
mobile equipment, medium pressure i.e. motors, valves & control
XP10
low-medium pressure systems, heavy industry, cylinders, steering unit (load sens.)
21/19/16
/03
22/20/17
low pressure systems
/03
/03 /1 # 10 /3 # 20
23/21/18
low pressure systems with large clearance
26/24/20
low pressure systems with large clearance
Hydraulic Filters & Accessories • 33
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