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The necessity of adding a filter before the solenoid valve

- Oct 25, 2018 -

 Do you want to add a filter before the solenoid valve? How to add? What are the benefits of doing this? If the filter is too fine, it will affect the flow of the medium. If it is too thick, it will not achieve the purpose of filtration. What kind of medium is suitable for the filter? Is it necessary to have a filter device before all the solenoid valves? This article will focus on the need for a filter in front of the solenoid valve.

High temperature solenoid valve

   The inner cavity of the solenoid valve is a structure without a filler function. Its working parts are directly in contact with the medium. The cleanliness of the medium directly affects the reliable operation of the working part. Among them, the sliding gap of the moving iron core involves the cleanliness of the medium, especially the main If there is a sliding gap in the valve spool, the long-term, large amount of residual impurities in the medium in the gap directly determines whether the solenoid valve can work reliably. Therefore, we should consider the sliding clearance, especially from the sliding clearance of the main valve. Filtration accuracy.

  There is a sliding clearance when the solenoid valve main valve spool is working. Its gap size is related to the value type and the size of the valve. It is usually 0.08~0.3mm, and the sliding gap is about 0.1mm when the moving iron core is working. Therefore, people can bilaterally The gap is 0.08 mm to consider the filtration accuracy. Due to the presence of a certain amount of impurity particles larger than 0.08 mm, the main valve spool may be stuck and it is difficult to work reliably.

   Experiments show that when the filter mesh diameter is 0.125mm, in the hydraulic system with working pressure less than 14.0MPa, the impurity particle size is 0.025~0.05mm. When the mesh oil filter is installed on the oil suction pipe, the filter mesh diameter is 0.8. ~1.3mm, the normal particle size after filtration is 0.13~0.4mm.

Therefore, it can be assumed that, from the concept of probability, when most of the impurity particles in the filtered medium are not larger than 0.04~0.08mm, the aperture of the filter may be 0.1~0.48mm, which is a single-side sliding gap or a bilateral sliding gap. 2.5 to 6 times, at this time, the solenoid valve can work normally.

Double coil self-maintaining explosion-proof solenoid valve

  Due to the special nature of the solenoid valve, the requirements for the cleanliness of the medium are high. In order to prevent impurities from entering the solenoid valve, a filter or Y-filter is usually installed in front of the valve. The standard of the filter, we usually calculate by the number of meshes.

   The so-called mesh number is the number of meshes in a square inch of filter area. For example, if there are 80 meshes on a square inch filter, then the filter is 80 mesh. In a square inch filter area, the greater the number of filter holes, the higher the precision of filtration and the ability to filter out finer impurities. Conversely, the smaller the number of filter holes in a square inch of filter area, the lower the precision of the filter, and only the larger impurities can be filtered out.

   The 80-mesh filter can filter out impurities with a diameter of 0.18 mm or more, and impurities less than 0.18 mm cannot be filtered out. You can choose a more suitable filter according to the actual working conditions.

   In summary, we recommend that it is more suitable to select 80~120 mesh for the filtration accuracy of liquid medium such as water. It is more suitable to use 100-200 mesh for the filtration medium.