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Hydraulic Oil Maintenance |
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Maintenance
The hydraulic oil should be kept clean ensuring good filtration and prevention of external as well as in-house impurities. The care of hydraulic oils starts before they are used into the system. The following points need to be kept into mind: · The oil barrels during need to be kept horizontal to prevent water or other contaminants from collecting. The gasket inside the bung should be kept wet for an effective use as an airtight seal. · The oil inside the barrel can get contaminated by ingress of airborne moisture or rust formation inside the barrel wall in the air space above the fluid. The oil from barrel needs to be pre-filtered before it is put to use in the system.
Oxidation
A dominant factor which determines the service life of the oil is degradation through oxidation. Oxidation occurs when oxygen combines with the original hydrocarbon molecules and gives a chain reaction. Traces (even a few parts per million) of certain metals, particularly copper, iron, zinc, lead and water act aE catalysts and markedly increase the rate of oxidation.
Oxidation produces soluble as well as insoluble products and these may form sticky substances and may deposit as gum or sludge in oil passages, various pump parts, valve spools and ports, etc. blocking them and restricting oil flow and making the machine run sluggishly. As a result of oxidation, the oil becomes progressively darker and gets acidic properties which ultimately deteriorates the life of the oil.
Steps to Combat Oxidation
Anti-oxidant additives are used in hydraulic oils to combat oxidation. Apart from this one can use other means to retard oxidation rate by:
Installation of heat exchanger when oil temperature exceeds 60°C. Incorporating magnetic plugs and filters to flush out ferrous contaminants. Keep out copper and brass tubings from the system if the pressure rating is above 10 bar.
When magnetic plugs are used, provision should be made to facilitate frequent cleaning of the plugs, otherwise oil surge in the tank may dislodge the particles from the magnet and circulate them back into the system. Incidentally, use of magnetic plug reduces load on filters.
Change of Oil
When oil changes are effected, the system has to be thoroughly flushed to remove the old oxidised oil; partially oxidised oil is an effective catalyst for the oxidation of fresh oils. Flushing is done with same oil or with flushing oil at 40°-50°C and should be continued till the filter is seen without any trace of contaminants.
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General Hydraulic Info 
