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If you have used a hydraulic system, you should know that the filter is very important to keep the system clean and prolong the service life of the system. Therefore, these points should not be ignored when we choose the system filter. Let us understand together. Next!
Each machine and component in the hydraulic system has its own set of requirements, and each requirement will affect each other, and of course also affect the selection of filters. To determine the size of the filter and choose a suitable filter, you must understand the following 5 key information:
1. The performance requirements of the filter
The performance requirement of the filter is usually expressed by the filter ratio β, that is, the ratio of the particles entering the filter to the particles exiting the filter.
The current hydraulic filter adopts a medium design, which can capture and contain more pollutant particles than before, thereby reducing pressure drop and prolonging its service life. For example, the filter ratio β of applications that require high-performance components will usually exceed 1000 (that is, 1000 particles enter the filter and only one particle passes).
2. Hydraulic system
After determining the performance requirements of the filter, we need to know the hydraulic components installed in the hydraulic system circuit. According to industry standards, these hydraulic components need to have corresponding standard filter types. This standard promotes ISO cleanliness code requirements and helps determine the correct filter element type.
For example, the proportional valve in the loop may require a 20/18/15 ISO cleanliness code. In order to meet the standards set by the ISO code, the circuit needs to have a 3 µm or 6 µm absolute filter filter. When selecting the size of the filter, it is also necessary to consider factors such as dirt holding capacity, pressure drop, cost, etc., understand which hydraulic components are attached to the filter, and understand how these hydraulic components affect the performance requirements of the filter, which can save costs.
3. Hydraulic fluid viscosity
The oil viscosity has a great influence on the size of the filter. When choosing a filter, many people tend to ignore this factor, and often choose a larger filter than the actual need, resulting in higher operating costs.
The filter size is too small and the pressure drop is too high, causing the clogging indicator to trip prematurely.
If the size of the filter is too large, it will cause problems such as high cost, large floor space, and high replacement cost. We should fully understand the normal temperature range of the hydraulic system and select the filter based on the exact lowest temperature.
4. Understand the clogging indicator
Assuming that the filter of the system has a clogging indicator (analog or digital), the user should have an appropriate target for the pressure drop when selecting the filter size.
Generally, the pressure difference range for the clogging indicator is 1 to 8 bar, and the ratio of the clogging indicator setting to the cleaning pressure drop is at least 3:1. For example, suppose the filter has a 5 bar clogging indicator. According to a ratio of 3:1, the acceptable maximum cleaning pressure drop target is about 1.7 bar.
Without understanding this principle, we may choose the size of the filter incorrectly. Although a filter that is too large can ensure the highest amount of protection, it will increase the cost.
5. Understand the system flow
The flow rate must be considered when selecting the size of the filter, and we need to consider the maximum flow rate.
Note that the intermittent flow may exceed the maximum flow of the pump. For example, the accumulator circuit, in which the accumulator stores a certain amount of pressurized fluid and releases it into the system to supplement the pump flow. The flow through the pressure filter downstream of the accumulator should take this extra flow into account.
Underestimating the flow through the filter will increase the pressure drop through the filter element and increase operation and maintenance costs.
The above content is the selection of hydraulic system filters shared by the editor, and I hope it will be helpful to everyone.
Each machine and component in the hydraulic system has its own set of requirements, and each requirement will affect each other, and of course also affect the selection of filters. To determine the size of the filter and choose a suitable filter, you must understand the following 5 key information:
1. The performance requirements of the filter
The performance requirement of the filter is usually expressed by the filter ratio β, that is, the ratio of the particles entering the filter to the particles exiting the filter.
The current hydraulic filter adopts a medium design, which can capture and contain more pollutant particles than before, thereby reducing pressure drop and prolonging its service life. For example, the filter ratio β of applications that require high-performance components will usually exceed 1000 (that is, 1000 particles enter the filter and only one particle passes).
2. Hydraulic system
After determining the performance requirements of the filter, we need to know the hydraulic components installed in the hydraulic system circuit. According to industry standards, these hydraulic components need to have corresponding standard filter types. This standard promotes ISO cleanliness code requirements and helps determine the correct filter element type.
For example, the proportional valve in the loop may require a 20/18/15 ISO cleanliness code. In order to meet the standards set by the ISO code, the circuit needs to have a 3 µm or 6 µm absolute filter filter. When selecting the size of the filter, it is also necessary to consider factors such as dirt holding capacity, pressure drop, cost, etc., understand which hydraulic components are attached to the filter, and understand how these hydraulic components affect the performance requirements of the filter, which can save costs.
3. Hydraulic fluid viscosity
The oil viscosity has a great influence on the size of the filter. When choosing a filter, many people tend to ignore this factor, and often choose a larger filter than the actual need, resulting in higher operating costs.
The filter size is too small and the pressure drop is too high, causing the clogging indicator to trip prematurely.
If the size of the filter is too large, it will cause problems such as high cost, large floor space, and high replacement cost. We should fully understand the normal temperature range of the hydraulic system and select the filter based on the exact lowest temperature.
4. Understand the clogging indicator
Assuming that the filter of the system has a clogging indicator (analog or digital), the user should have an appropriate target for the pressure drop when selecting the filter size.
Generally, the pressure difference range for the clogging indicator is 1 to 8 bar, and the ratio of the clogging indicator setting to the cleaning pressure drop is at least 3:1. For example, suppose the filter has a 5 bar clogging indicator. According to a ratio of 3:1, the acceptable maximum cleaning pressure drop target is about 1.7 bar.
Without understanding this principle, we may choose the size of the filter incorrectly. Although a filter that is too large can ensure the highest amount of protection, it will increase the cost.
5. Understand the system flow
The flow rate must be considered when selecting the size of the filter, and we need to consider the maximum flow rate.
Note that the intermittent flow may exceed the maximum flow of the pump. For example, the accumulator circuit, in which the accumulator stores a certain amount of pressurized fluid and releases it into the system to supplement the pump flow. The flow through the pressure filter downstream of the accumulator should take this extra flow into account.
Underestimating the flow through the filter will increase the pressure drop through the filter element and increase operation and maintenance costs.
The above content is the selection of hydraulic system filters shared by the editor, and I hope it will be helpful to everyone.
