For lubricating and hydraulic oils the requirements regarding purity have increased considerably. The tolerances of ball bearings are becoming smaller, as they have to withstand increasing speed and increasing load. The same is true for gear transmissions, where gears grip more and more accurately, whereby not only speed has increased, but also the torque.
In the lubrication technique, the same standards for determining the purity of the oil are used as in hydraulics (IISO DIS 4406 or NAS 1638). In contrast to hydraulics, oils of high or very high viscosity are mainly used in the lubrication technique.
For the filtration technician, such high viscosity of lubricating oil means that its characteristics should be taken into account when choosing a suitable filter. It must be ensured that lubricating oil can be filtered at very low differential pressure, even when it has not yet reached full operating temperature. Thereby we use filters that are structured similarly or the same as in the filtration of the hydraulic system.
The oil flow allows for the free movement of hard particles and consequently the wear of the mechanical elements throughout the whole system. In order to avoid these inconveniences, housings with cleaners are installed in the system.
The oil cleaner cartridge is used for the main lubricating oil flow. In lubricating or engine oil systems, cleaners in the form of cartridges or threaded cleaners are installed. To ensure good operation and lubrication of the system, in addition to changing the cleaner, the oil must also be replaced within the service time. The permeability, size and other parameters of the cleaner are determined according to the existing housing, flow, quality of filtration, requirements of the machine or device manufacturer and the purpose of using the cleaner itself. Compared with hydraulic cleaners, oil cleaners are usually of a slightly weaker structure.
Recently, so-called ECO filters have been present on the market. They are almost entirely made of environmentally friendly materials. ECO filters are distinguished by the markings and extensions of the cleaner, which are made of various plastics or resins.
Advantages of filtering:
- The combination of different filters ensures efficient protection of the components, given that filtration can help to maintain the purity of the oil.
- Filtering slows down the process of oil ageing.
- We can avoid expensive repairs and time periods without operation.
- The life of lubricating oils is considerably prolonged.
How filter elements work in the filter system
Filter elements stop particles and dirt and allow for the free flow of the liquid. In order for the liquid to flow through the filter element, the latter must include holes or channels which direct the flow of the liquid and allow it to pass through. Therefore, the filter elements are made of a permeable network of fibres that change the flow of the liquid and direct and accelerate it.
When the liquid comes into contact with the fibres, it changes direction as shown in the figure. When the liquid flows through the filter element, it changes direction within the intertwined filter fibres. As it passes through the thick layers of fibres, it becomes cleaner and cleaner. It is usually considered that the thicker the filter element, the greater its dirt retention capacity.
The cross-section of the fibres shows how the flow is accelerated in the places of fibre openings:
There are four basic methods of capturing particles
Inertia
The first method is inertia and it is used for larger and heavier particles in the flow. These particles are heavier than the fluid that surrounds them. When the fluid changes direction and flows through the fibres, the particle continues its way in a straight line and is caught in the fibres.
Diffusion
Another method of capturing particles is diffusion,which is used for the smallest particles. Small particles cannot be held in place by a viscous liquid, so they are dispersed in the flow. When crossing the flow, the particles collide with the fibres and are caught.
Interception
The third method of capturing the particles is interception. Direct interception is used for medium-sized particles, which are too small for inertia and too large for diffusion in the flow. These medium-sized particles move with the liquid when it is passing through the fibre openings. The particles are caught when they collide with the fibres.
Sieving
The fourth method of capturing is sieving, which is in fact the most common hydraulic filtration mechanism and in which the particles are too large to pass through the holes in the fibres.
Servicing of oil systems
Our company can also provide you with servicing when it comes to care and maintenance of oil systems. We ensure clean oil for your carefree sleep in three stages:
- Stage 1: Determining oil status. We offer you the Trend of oil purity control directly on the machines themselves, laboratory oil controls in independent laboratories and consulting in the field of care and maintenance of oil. Before moving to the second stage, the customer is advised to change all filters, clean the tanks and continue to service the existing oil, if appropriate for further use.
- Stage 2: Performing a high-quality oil servicing, whereby the oil system is cleaned by installing filter systems that will also work during the operation of the machine. The devices operate for as long as the oil and the system are not clean to the extent recommended by the manufacturers of each of the components. All work carried out is documented with reports and results.
- Stage 3: We offer continuous control of impurities or a regular inspection of the state of the oil. We can also upgrade the system of continuous oil servicing, if so requested by the customer.
