In the turbine hydraulic system, the servo valve is the core component of precision control, and its operating stability directly affects the efficiency and reliability of the equipment. However, frequent servo valve jamming failures often become a problem that plagues power plants. Studies have shown that the root cause of such failures is closely related to the cleanliness of the hydraulic oil, and the filter element is the “first line of defense” for oil contamination, and its performance directly affects the reliability of the system. Next, we take the LH0060DO025BN/HC hydraulic oil station filter element as an example to deeply analyze the correlation mechanism between the hydraulic oil cleanliness level and the servo valve jamming, and propose a systematic solution.

1. Hydraulic system cleanliness: the invisible pusher of servo valve failure

The working principle of the hydraulic servo valve is based on the micron-level precision fit clearance between the valve core and the valve sleeve, and its dynamic response accuracy can reach 0.1μm. This high-precision feature makes it extremely sensitive to pollutants: when there are solid particles with a diameter larger than the valve core gap in the oil, it may directly cause the valve core movement to be blocked; and the continuous accumulation of submicron particles will cause scratches on the valve core surface, increase the fit clearance, and eventually cause flow control inaccuracy.

The ISO 4406 standard divides hydraulic oil cleanliness into 21 levels. Servo valve manufacturers generally require that the system cleanliness be controlled within ISO 15/13/10, which means that the number of particles larger than 4μm per milliliter of oil must be less than 2400. If the oil cleanliness deteriorates to ISO 18/16/13, the servo valve jam failure rate will increase by 5-8 times.

2. Technical characteristics of LH0060DO025BN/HC filter element

As the core filter unit of the hydraulic oil station, the LH0060DO025BN/HC hydraulic filter element adopts a multi-layer composite structure design, and its technical parameters directly determine the system cleanliness maintenance capability:

Filtration accuracy and β value: According to laboratory tests, the filter element can stably reach ISO 14/12/9 at a rated flow of 25L/min, meeting the long-term operation requirements of the servo valve.

Pollution holding capacity and life: The filter element adopts gradient density glass fiber material, and its pollution holding capacity is 40% higher than that of conventional filter elements. The pressure differential alarm device can ensure timely replacement before the pollutant is saturated, avoiding secondary pollution caused by the opening of the bypass valve.

Material compatibility: The shell is made of aluminum alloy anodized, and the filter material is resistant to oil temperature up to 120℃. It has good compatibility with HM/HV series hydraulic oil, and effectively avoids the attenuation of filtration performance caused by material swelling.

3. The chain effect of filter element performance degradation on cleanliness control

The performance attenuation of the hydraulic oil station filter element LH0060DO025BN/HC will cause systemic risks. Especially in the case of overdue use, the filter element β₃ value decreases, and the interception efficiency of particles decreases. At this time, the cleanliness of the system will gradually deteriorate, and the risk of servo valve jamming will increase by 3 times.

Pressure differential oscillation is another influence. When the filter element is blocked and the inlet and outlet pressure difference is greater than 0.3MPa, the turbulent effect will cause the captured particles to re-enter the oil. A case study of an injection molding machine shows that this type of “secondary pollution” can instantly increase the concentration of 10-15μm particles in the oil by 20 times.

The bypass failure of the oil station filter element LH0060DO025BN/HC will also affect its filtration performance. The bypass valve opening pressure deviation of the inferior filter element is too large, and it may be delayed in opening when suddenly blocked, causing the filter element to rupture. A mining hydraulic station once caused the servo valve to be completely stuck within 30 minutes.

4. Systematic solution

Based on the analysis of the failure mechanism, a three-level prevention and control strategy is proposed: high-precision filter elements are preferred, and the initial filtration efficiency is increased to more than 99.5%. A particle counter is installed to achieve real-time cleanliness monitoring, and ISO 16/14/11 is set as the warning threshold. A pressure difference-time dual-factor model for filter element replacement is established: forced replacement when the operating time is greater than 5000 hours or the pressure difference is greater than 0.25MPa.

Hydraulic oil cleanliness control is a systematic project. The performance of the lubricating oil filter LH0060DO025BN/HC directly affects the reliability of the servo valve. Stable control of oil cleanliness within ISO 15/13/10 can extend the mean trouble-free working time of the servo valve and provide a solid guarantee for the efficient operation of the equipment.

When looking for high-quality, reliable steam turbine oil filters, YOYIK is undoubtedly a choice worth considering. The company specializes in providing a variety of power equipment including steam turbine accessories, and has won wide acclaim for its high-quality products and services. For more information or inquiries, please contact the customer service below:

E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

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