Importance of fluid cleanliness in hydraulics

1. Importance of fluid cleanliness in hydraulics • Looking to the modern machinery requirements hydraulics play a very active & crucial role in machine drives. As the high-precision machinery uses advanced hydraulic components like axial pumps & proportional valves maintenance of such elements is the most vital necessity. • In hydraulics more than 80% of problems are due to contaminated fluid & so it is important to keep system fluid very clean & free of contaminants. Looking to these points latest concepts & methods of oil cleaning should be taken in prime consideration.

2. Tasks of a Hydraulic Filter

3. Particle Proportions 75 Diameter in µm Human hair 30 15 5 1 Bearinglubrication film Fine/coarseparticle

4. Contamination Classes • NAS 12 ISO 21/18 Fresh oil, delivery in barrels • NAS 9 ISO 18/15 Fresh oil, delivery in tank trucks • NAS 7 ISO 15/13 Fresh oil, delivery in mini containers • NAS 5 ISO 14/11 Required for modern hydraulic systems

5. Filtration Technology Development Year Development Filtration rate 1940 First use of air and oil filters for 100 µm engines; strainers 1950 Big increase of hydraulic applications and so filtration 1960 Use of star pleated 50 to 100 µm mesh packs with inner core 1970 Development of paper and up to 3 µm metall fleece elements nominal 1980 Launch of the Multipass Test, up to 3 µm start of absolute filtration absolute 1990 Absolute filtration in all applications 1 µm and 2µm absolute

6. Origins of Contamination • External contamination • Internal contamination • Assembly • Initial contamination • Abrasion • New oil • Repairs

7. Effects of contamination (Wear due to dirt particles)

8. Clearances in various hydraulic components-01

9. Surface & Depth filtration

10. Filter arrangement in hydraulic system

11. Suction line filter

12. Pressure Line Filter

13. Typical selection chart for pressure line filters

14. Return Line Filter

15. Typical selection chart for suction & return filters

16. Filler & Breather with filling sieve

17. Typical selection chart for filter in breather

18. Cleanliness classes as per ISO 4406

19. Cleanliness classes as per NAS-1638

20. Comparison of Contamination Classifications

21. Recommended filter pore sizes for Rexroth components

22. Degree of separation Beta ratio

23. Filter efficiency

24. Some facts about contamination problem & filters • From time to time development has taken place for better method of oil cleaning. A continuous research & innovation is going on world-wide for Better & better filter technology. • Contamination ingress in hydraulic system cannot be brought to zero. • To clean the oil to a certain class is not difficult but what difficult is, to maintain that cleanliness level consistently during working cycles. • As you go for fine filter you should be more careful & prompt to keep watch on filter clogging & replacement. • We cannot keep hydraulic systems healthy without filters & protection to hydraulic system can be given by on-line filters only & not by other off-line cleaning methods.

25. Electrostatic cleaning method • Electrostatic cleaning can be useful to control micro-level contaminants. • Particularly if your main trouble is fine particles this can be very useful method for off-line cleaning.

26. Working principle of ELC machine

27. Cleaning range of ELC M/c. (General Idea)

28. Filter is a must • ELC is good technique for removal of micro-level contamination. ELC concept reduces the danger of hydraulic system malfunction where very small particles can affect severely. Moreover continuous running of ELC systems reduces load on working filters of the system. • But a misconception that ELC can take place of filtration should be removed from one’s mind. On-line safety of hydraulic components can be achieved with protection filters only & not with ELC methods.

29. The Drive & Control Company Thanks for your attention