Misunderstandings in filter selection and use

Mainly introduces the selection of filters in hydraulic systems and some common misconceptions and methods in daily use, and proposes reasonable selection and correct usage. Keywords: pollution control; over-injector; selection; use; misunderstanding
As the main component of pollution control in hydraulic systems, hydraulic filters are designed and selected appropriately, and whether their daily use (maintenance) is Correctness is directly related to the safety and reliability of the system. In practical applications, many users still have many misunderstandings about filter selection and use. If not corrected, it will affect the normal and reliable operation of the hydraulic system.
Misunderstandings in filter selection in hydraulic systems
Misunderstanding 1: Choosing a high-precision oil suction filter can not only effectively protect the pump, but also ensure the cleanliness of the system Degree
Because particulate pollutants in the oil will increase the wear of the pump and affect the performance and life of the pump, large particle pollutants may also jam the pump, seriously affecting the safety and safety of the system. Reliability. Therefore, some users choose high-precision oil suction filters, thinking that they can both protect the pump and ensure the cleanliness of the system. However, the high-precision oil suction filter is prone to clogging due to excessive pollutants, causing the pump to not absorb oil smoothly, resulting in empty suction, accelerating pump wear, and seriously affecting system safety. Therefore, the pressure drop of the oil suction filter must be strictly controlled. control. Generally, hydraulic systems can consider installing low-precision oil suction filters to protect the pump, and install filters in front of components that are sensitive to contaminants to protect them to control the impact of particulate pollution. In order to effectively intercept contamination caused by component grinding or external intrusion in the circuit, it is recommended to install an oil return filter for control to improve the oil cleanliness of the entire system.
At the same time, the pipelines and fuel tanks should be thoroughly cleaned before the system is operated to ensure the degree of oil contamination. In this way, the oil contamination of the entire system is basically controlled, which protects both the pump and the entire system.
Myth 2: The rated (nominal) flow rate of the transducer is the actual flow rate of the system
The rated flow rate of the transducer is when the oil viscosity is 32cst. The flow rate of oil passing through the clean filter element under the specified original resistance. However, in actual applications, due to different media used and different temperatures of the system, the viscosity of the oil will also change at any time. If a filter is selected based on 1:1 between rated flow and actual flow, when the viscosity of the system oil is too high, the resistance of the oil passing through the filter will increase (for example, the viscosity of No. 32 hydraulic oil 00c is about 420cst), or even When the pollution and clogging signal value of the filter is reached, the filter element is considered to be clogged. Secondly, the filter element of the filter is a wearing part and is gradually contaminated during operation. The actual effective filtration area of ​​the filter material continues to decrease, and the resistance of the oil passing through the filter quickly reaches the value sent by the pollution and clogging transmitter. In this way, the filter needs to be frequently cleaned or the filter element replaced, which increases the user's cost.
At present, all domestic injector manufacturers have stipulated the rated flow rate of the filters they produce. Based on past experience and the use of many customers, when the oil used in the system is general hydraulic oil, this discussion When selecting the filter, select it according to the multiple of the following flow rates: a. The rated flow rate of the oil suction and oil return filters is more than 3 times the actual flow rate of the system; b. The rated flow rate of the pipeline filter is 2.5 times the actual flow rate of the system. above. If the oil used is other than general hydraulic oil or high-viscosity hydraulic oil, please consult the manufacturer for selection.
Myth 3: The higher the precision of the filter, the better
Solid contamination in the hydraulic system is the main cause of hydraulic system failure, so high-precision filtration is used devices to control pollution. In fact, this is not the case. This not only increases the manufacturing cost of the system, but also shortens the service life of the filter element. So how to choose the precision of the filter reasonably? It is mainly determined by the oil contamination requirements of the components of the hydraulic system. The higher the cleanliness required for the components, the higher the accuracy of filter selection. When wear particles enter the kinematic gap of the components, wear will occur. chain reaction. Therefore, in order to reduce the wear to a minimum and extend the life of the components to the maximum extent, it is necessary to filter out particles similar to the gap size.