Can Hydraulic Oil Life and Hydraulic System Life be Extended?
Can Hydraulic Oil Life and Hydraulic System Life be Extended?
Can Hydraulic Oil Life and Hydraulic System Life be Extended?
Can the hydraulic oil life be extended?
The life of hydraulic oils is not unlimited. Hydraulic oil manufacturers subject their oils to extreme pressure and temperature conditions through trials and tests, and it is expected to withstand these conditions in a reasonable time. However, it is usually the machine manufacturers who determine the oil life to the customer. The reason for this is that the environment in which the machines and benches work and the pollution resistance limits of the parts used in the machines change.
Therefore, it is the machinery manufacturers, not the oil manufacturers, that determine the service life for hydraulic oil. AS AN EXAMPLE: While an oil change is required for 1000 hours when used in normal conditions in a construction machine, the oil life is foreseen as 500 hours for the same type of oil if the working conditions of this machine change and it is used in extremely dirty environments (such as installing a crusher).
The same type of oils used in construction machinery are also used in industrial applications and these oils are used for more than 1000 hours.
Improvements in filtration capabilities, anyway, lead to prolonging the life of the oil used in machinery. The difference here is due to the improvement of the filtering abilities rather than the content of the oil. Higher quality and high viscosity index hydraulic oils can last longer in use.
However, regardless of the physical and chemical properties of the hydraulic oil, the most important limitation on the life of the oil is the pollution in the oil.
What are the factors that determine the hydraulic oil life?
- Criteria determined by the oil producer: Viscosity, acidification, amount of water in the oil
- Criteria set by the machine manufacturer: particulate contamination
In general, oils have to be changed due to contamination long before the physical and chemical properties of the oil are depleted.
The reason behind the fact that the oil life is extended is to remove this pollution and ensure that the oil is used during its normal life. See:Factors affecting oil life and oil change (About Oil page)
What is the By-pass filter application in the Hydraulic System?
In hydraulic and lubrication systems, while all of the circulating oil passes through the system's own filter, in the BY-PASS (shortcut-connection, bridging) application, a small part of the oil is taken from the system and returned to the oil tank by being filtered through the BY-PASS filter.
What should be the Off Line filter capacity in the hydraulic system?
Off Line filtration system capacity is selected according to the hydraulic oil tank capacity of the machine. The Off-Line Filter system cleans the oil it takes in small flow rates and gives it directly to the tank, and within a few days at most, all the oil in the system is cleaned at a fine level.
If the oil is taken from the tank and transferred to the same tank after it is filtered, then as a general rule, an oil amount of 7-8 times the tank capacity should flow through the fine Off-Line filtering unit.
If the off-line filter is taken from a tank and given to a separate clean oil tank in practice, then all the oil is cleaned in one pass.
Capacity adjustment is very important and it is necessary to act according to the filter supplier's recommendations.
Where should the connection be made in the application as ON-LINE in the hydraulic system?
Oil should be taken from the machine's oil sampling points or pressure measurement points, or return lines, if possible, never from the function circuits or pilot circuits.
Why don't machine builders install Finer Filters?
For example, the amount of oil flowing per minute in a 30-ton machine is 450-500 liters. If that much oil passes through the filter, it is necessary to keep the number of Off-Line filters too high.
What is the difference between depth filtering and surface filtering?
Surface filters are filled with dirt particles as oil passes from one surface to the other. Before the filter, the pressure rises and forces these particles to pass through the pores of the element, the element is perforated and the phenomenon called TUNNING occurs.
In deep filtration, since the dirt particles leave the dirt while passing between the element windings, the oil passage becomes more difficult as the filter is filled and the filtration sensitivity of the filter element increases. It is necessary to replace the element when oil passage becomes more difficult. TUNNING event does not occur because the dirt is trapped between the material windings while the oil passes deeply.
On the other hand, deepening filtering elements have a much larger filtering surface area than surface filters due to their roll-wrapping feature and have a higher dirt holding capacity.
In deep filtration, coarse dirt particles are kept on the outside, while fine dirt is kept on the inner bottom windings and dirt particles are kept at the maximum level.
Can the hydraulic oil life be extended indefinitely?
NO. For this, it is necessary to look at the viscosity of the oil, its acidification (TAN in hydraulic oils, TBN in motor oils, water-in-oil emulsion, etc.). Oils are obtained by adding some chemicals to the base oil as needed. It prevents the air from holding in the oil.The depletion of these additives causes problems in the use of the oil.
Is pollution a reason to change oil?
YES for machine builders; NO for oil manufacturers.
Oil manufacturers give an OIL CHANGE warning in their analyzes if values such as viscosity and acidification are not within normal limits. If these are within normal values and pollution is detected, they will give a warning as NORMAL, FILTER YOUR OIL WELL.
Can we extend oil life by using long life oil?
If pollution is not controlled NO!. But if you improve your filtration system YES! Long-lasting oils are oils with chemical additives that improve oxidation, detergency, and resistance to temperature and pressure. However, the pollution level of the oil is important for certain parts of the machines. If you use long-lasting oil but cannot ensure the cleanliness of your oil, the oil will become contaminated above NAS 9 in a short time, and in this case the acceptable limits for the machine manufacturer will be exceeded.
Is a 2 micron filter necessary to extend the oil life?
YES. In oil analysis, the ISO standard counts particles at 4 micron, 6 micron and 14 micron levels, and the NAS standard 5-15, 15-*25, 25-50 microns. OEM filters on the machine can only filter 10 microns, no matter how effective they are. In other words, when particles below 10 microns in the oil exceed a certain limit, that oil becomes an unacceptable oil for machine components. For example, even if the oil analysis shows ZERO contamination in ISO or NAS scale for 14 microns and above, in low microns (below 15 microns), if the contamination goes above NAS9 or ISO 19, THIS OIL IS DIRTY OIL FOR THE MACHINE MANUFACTURER.
For this reason, in order to prolong the oil life, filters must be used with the precision of holding particles between 2-10 microns.
Do fine filters retain chemical additives in the oil?
NO! These additives are in a molten state and do not remain in the filter, no matter how sensitive the filter pores are. However, on the contrary, the increase in the rate of eroded iron in the oil causes these chemical additives to attach to the iron and be removed from the oil. Proliferation of metal wear elements in oil also accelerates wear, and pollution and wear trigger each other. For this reason, reducing the abrasive pollution in the oil and keeping the worn iron element by the filters have a positive effect on the oil life.
Is the new oil coming out of the barrel in ideal cleaning?
NO! It is known by everyone who is curious that the oil spilled from the barrel is at the limit of pollution. These oils are NAS9 or dirtier. Some conscious manufacturers (construction machines or precision workbenches) subject their machines to fine filtration when putting new oil. On the other hand, the presence of pollution and water in storage systems (fixed tank, vehicle oil tank, etc.)
Do we clean the machine oil completely by changing the Hydraulic Oil?
NO! Approximately 20% to 30% of the total oil used in the machine remains in the installation (cylinders and lines, etc.). For example, 300 liters of oil is put into the system in a work machine. However, in the oil change, 200-230 liters of oil are changed in the oil tank. In oil change, this new oil is mixed with 80-100 liters of oil remaining in the installation. Moreover, it should be taken into account that the oil coming out of the barrel is at a limit pollution level like NAS 9-10. This ratio reaches 45% for 70-80 tons excavator. In other words, the new oil you put in the machine is polluted with the old oil in the installation, forcing the pollution limit from the very beginning.
How important is hydraulic oil cleaning for the machine?
It varies depending on the application area of the machine and the sensitivity of the hardware used on it. For example, if a gear pump is used in the system, it is allowed up to NAS 9-10 pollution, while if a piston pump is used, oils with more than NAS 8 pollution are dangerous. In systems using servo valves, the maximum allowable contamination is NAS6.
Pollution that poses a real threat to a construction machine and workbench is those that are large enough to get between moving sensitive parts (under 10 microns).
How does the presence of water in Hydraulic Oil affect?
In filters with cellulose elements, water quickly deteriorates the filter elements. Since the cellulose element surface ratio is much higher in the deep filter system, they can hold 0.5% water. However, when water causes swelling, distortions and breaks in the cellulose elements, the life of the element ends.
In these cases, it is necessary to use special water-retaining filters. This will extend the oil filter element life.
Does hydraulic oil cleaning have a significant effect on machine life and failure rate?
ABSOLUTELY YES! 80% of hydraulic system failures are due to the use of dirty oil. According to the research of the British Hydromechanical Society, which lasted for 3 years, when the oil cleaning is improved by 2-3 stages, the machine life is extended by 2 times. While pollution over 10 microns causes clogging in the system, pollution below 10 microns enters between the components working with narrow tolerances and causes wear and weakening of function. For example, if a piston pump wears out, significant loss of function and efficiency occurs and must be overhauled.
On-line cleaning or off-line?
Oils can be subject to continuous cleaning on-line, as well as off-line, during maintenance periods or at reasonable intervals. In case of on-line filtration, a continuous cleaning is ensured in the entire system and components are protected from wear and clogging, as well as prolonging the life of the OEM filters of the vehicle-machine (3 micron cleaned oil will also eliminate the dirt load on the 10 micron OEM filter). On the other hand, since the contaminated oil will get hotter and the operation of the oil in a hotter environment than normal will accelerate the depletion of the physical properties of the oil, the prolongation of the oil life is guaranteed.