Discussion on the necessity of adding filter in front of solenoid valve

Do you want to add filter device before solenoid valve? How to add? What are the benefits of this? Filter screen added too fine will affect the medium flow, add too coarse and can not achieve the purpose of filtering, what kind of media filter will be more suitable, is not all the solenoid valve before the need for matching filter device, this article will focus on the solenoid valve before the necessity of filter.
Solenoid valve cavity belongs to no packing box type structure, its working parts directly contact with the medium, the cleanliness of the medium directly affects the reliable action of the working parts, among which, the moving iron core sliding clearance involves the cleanliness of the medium, especially if there is a sliding clearance of the main valve spore, in the gap, a large number of medium residual impurities, Directly determines whether the solenoid valve can work reliably. Therefore, we should consider the filtration accuracy from the sliding clearance, especially from the sliding clearance of the main valve.
Solenoid valve valve core work there is a sliding clearance, its clearance size and value type and valve size related, usually 0.08~0.3mm, moving iron core working sliding clearance is about 0.1mm, so people can be a bilateral clearance of 0.08mm to consider the filtration accuracy, due to a certain number, greater than 0.08mm impurity particles, The main valve spool may be stuck and difficult to work reliably.
The experiment shows that when the filter diameter is 0.125mm, the size of impurity particles is 0.025~0.05mm in the hydraulic system with working pressure less than 14.0MPa. When the mesh oil filter is installed on the suction pipe, the filter diameter is 0.8~1.3mm, then the normal particle size after filtration is 0.13~0.4mm.
Therefore, it can be assumed that, from the concept of probability, most of the size of the impurity particles in the filtered medium is not greater than 0.04~0.08mm, the aperture of the screen is desirable to 0.1~0.48mm, that is, the unilateral sliding clearance or bilateral sliding clearance 2.5~6 times, at this time, the solenoid valve can work normally.
Solenoid valve because of its special structure, the medium cleanliness requirements are higher. In order to prevent impurities from entering the solenoid valve, filters or Y-shaped filters are usually installed in front of the valve. The standard of filter screen is usually calculated according to the mesh number.
The mesh number is the number of mesh holes in one square inch of screen area. For example, if there are 80 mesh holes in one square inch of mesh, the mesh will have 80 mesh points. The more holes you have on a one-square-inch screen area, the more accurate the filtration will be, and the finer impurities will be removed. On the other hand, the fewer holes in a one-square-inch screen area, the less accurate the filtration will be, and only the larger impurities will be filtered out.
80 mesh filter, can filter out diameter greater than or equal to 0.18 mm impurities, less than 0.18 mm impurities, can not be filtered out. You can choose a more suitable filter according to the actual working condition.
To sum up, we suggest that the filtration accuracy of liquid medium such as water should be selected as 80~120 mesh, and that of gaseous medium such as air and steam should be selected as 100~200 mesh.