Defeat contaminants in non-conductive fluids once and for all!
Electrostatic Oil Cleaning Systems from Friess remove particles as small as 0.1 µm and aging phenomena such as varnish and oxidation products. This not only increases the service life and durability of the oil, but simultaniously optimizes machine precision and reduces hydraulic malfunctions.
How does Electrostatic Cleaning work?
Our Oil Cleaning System is connected to the oil tank in a bypass flow. The oil is then transported from the reservoir to the Electrostatic Oil Cleaning System by means of a gear pump. There, electrodes charges with a voltage of 14,000 V ensure that contaminants contained in the oil are attracted and deposited on cleaning elements. The innovative Friess principle removes both hard contaminants such as metal particles, seal abrasion or chips, and soft contaminants such as oxidation products, varnish and sticky sludge particles.
The special feature of this method is that you are not limited by the pore size of your filter elements. Unlike other filters, the field forces of an electrostatic field act on particles of all sizes. As a result, you get a particularly clean oil that is even cleaner than new oil! Thus, you save yourself expensive and time-consuming oil changes.
The advantages at a glance:
The lubricating film between the individual components moving against each other is sometimes only 1 – 4 µm thin. If dirt particles are then pressed into this lubrication gap with the hydraulic oil, the particle interrupts the lubrication film. This can damage the surface and create new particles. These new particles generate further particles and the contamination of the oil increases exponentially. During operation, the tip of a gear or vane of a vane pump wears down more and more and the pump’s flow rate decreases. Internal leakage can occur in valves and the control precision of the hydraulic components decreases.
As the oil is pumped through the system at high speed and pressure, the particles contained in the oil hit edges, nozzles, etc. with high energy. This results in the particles damaging the surface on impact and producing new particles. In the long term, erosion leads to reduced control precision and internal leakage. Often, “washed out” piping and components are found in defective valves. Here, particles have steadily eroded material.
Oxidation products, also known as varnish, are aging phenomena of oil. This occurs due to the reaction of the oil with oxygen in the air. The oil is oxidized. Typically, this reaction is quite sluggish and slow. However, particles and contaminants in the oil act as a catalyst for this reaction. Therefore, the more particles are present, the faster the oil reacts with the oxygen.
The oil temperature also has an effect on the oxidation of the oil. At temperatures below 60°C, the reaction rate is relatively slow. At temperatures above 60°C, the reaction rate doubles for each temperature increase of about 10°C. For this reason, oil coolers are used to prevent the oil temperature from rising too high.
In the long run, varnish leads to considerable operating difficulties in the hydraulic system, since varnish is no longer a liquid but a solid. This causes valves to stick together and move more slowly. In extreme cases, the Varnish will completely gum up a valve and it will have to be replaced. Because of the particles contained in the Varnish, it is frequently also very abrasive.
Modern hydraulic systems are high-precision systems consisting of pumps, switching and control valves, cylinders or hydraulic motors. The hydraulic oil not only ensures power transmission, but also serves as a lubricant for the moving components. In general, it can be assumed that approx. 80% of all malfunctions in a hydraulic system are due to contamination of the oil.
Foreign substances such as dirt particles, water or varnish cause a wide variety of malfunctions and machine failures. This results in high oil consumption and very high operating costs.
Hydraulic components are already contaminated with dirt particles during assembly. Since pumps and valves are manufactured by machining, a large number of particles are present on the components at the end of assembly despite all efforts and cleaning stages. The hydraulic oil used for a test run of pumps and valves is often heavily contaminated with particles, as often no hydraulic filter or only a very coarse one is used during filling. Dirt from the piping and tubes enters the system during final assembly of the system.
Many users have seen a reduction in costs for repair, maintenance, downtime, oil change and waste oil disposal of up to 80% by using a customized cleaning technology for their hydraulic oil. In addition, many users have been able to significantly reduce the warranty claims of deliveries due to improved machine precision or clean oil in the test bench.
The less oil is consumed, the less oil has to be disposed of. Oil causes large amounts of CO₂ from its extraction to its disposal. If less oil is consumed, this has a positive effect on the environmental footprint of a company.
Oil cleaning and oil filtration have the same goal in mind: removing dirt particles from the oil. However, electrostatic oil cleaning systems have a different operating principle than oil filters. With the electrostatic field force, particles are attracted and bound to cleaning elements rather than pumped through a membrane with pores. This allows the oil cleaning system to remove much smaller particles, since it is not limited by a pore size, but the field forces work on all particles. Varnish is also affected by the electrostatic field. On the other hand, an oil purification system works slower than conventional filtration systems.
Nevertheless, both concepts should be used in a hydraulic system. They are not mutually exclusive. Filters should be installed in the inlet and outlet of the hydraulic system to protect the pumps. Filters are also essential when filling a system with new oil to reduce the amount of dirt entering the system. Hydraulic filters are also indispensable for coarse filtration. For the removal of the finest contamination and aging phenomena such as varnish in the oil, in order to be able to use the oil as long as possible, an electrostatic oil cleaning system is indispensable and a hydraulic oil filter is not sufficient.