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• SINFT
• 2025-04-03 08:50:13

Characteristics of Phosphate Ester Hydraulic Oil and the Impact of Impurities​

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Unique Chemical Structure and Properties​

Phosphate ester hydraulic oil belongs to synthetic hydraulic oils. Its base oil consists of phosphate ester compounds. This chemical structure endows it with excellent fire resistance. The phosphorus-oxygen bonds in the molecules are relatively stable and are not easily broken at high temperatures, effectively preventing the spread of flames and reducing the risk of fire. However, at the same time, phosphate ester molecules have strong polarity, giving them high solubility and adsorptivity to certain substances. Although this characteristic helps maintain the cleanliness of the hydraulic system to some extent, it also means that it is more likely to interact with impurities in the system, forming mixtures that are difficult to separate.​

Wide and Complex Sources of Impurities​

During the operation of the hydraulic system, phosphate ester hydraulic oil is exposed to various impurities. Externally, dust particles in the air, moisture, and other pollutants around the equipment can enter the oil through the tank breather, pipeline connections, and other channels. For example, in industrial sites with high wind and sand, the probability of dust particle intrusion increases significantly. Internally, impurities are mainly generated from the wear of equipment. Moving parts such as hydraulic pumps, valves, and hydraulic cylinders inevitably experience friction during long-term operation, generating metal debris, sealing material fragments, and other impurities. In addition, phosphate ester hydraulic oil may undergo chemical reactions such as oxidation and hydrolysis during use, producing aging products such as organic acids and polymers, all of which also become impurity components in the oil.​

Severe Hazards of Impurities to the System​

The presence of impurities can seriously affect the performance and lifespan of the hydraulic system. Solid particle impurities, such as metal debris and dust, act like tiny abrasives when flowing with the fluid in the oil, causing wear on the surfaces of hydraulic components. Take the hydraulic pump as an example. These particles may scratch the precision components such as the vanes and pistons of the pump, leading to a decrease in the volumetric efficiency of the pump, unstable output flow, and even pump failures. For high-precision control components such as servo valves and proportional valves, the impact of impurities is even more significant. Even tiny particles can cause the valve spool to stick, preventing the valve from opening and closing properly, thereby affecting the control accuracy and response speed of the entire system.​

Moisture is also an important contaminant in phosphate ester hydraulic oil. Since phosphate esters have a certain water absorption capacity, when moisture mixes into the oil, it accelerates its hydrolysis reaction, producing acidic substances. These acidic substances not only corrode metal parts, reducing the service life of the equipment, but also further promote the oxidation and aging of the oil, causing a sharp decline in the performance of the oil. At the same time, the presence of moisture may cause the hydraulic oil to emulsify, destroying its lubricating properties, increasing the viscosity of the oil, and affecting the normal operation of the system.​

Difficulties in Filtering Phosphate Ester Hydraulic Oil​

Fundamental Reasons for Poor Filterability​

Phosphate ester hydraulic oil has poor filterability, which is an important internal factor contributing to its high requirements for filtration accuracy. At the molecular level, the size and shape of phosphate ester molecules are relatively complex, and they have strong polarity, making them prone to forming hydrogen bonds or other chemical bonds with other molecules. When impurities are present in the oil, these impurity particles are often tightly wrapped by phosphate ester molecules, forming a stable colloidal system, making the filtration process extremely difficult. In addition, the relatively high viscosity of phosphate ester hydraulic oil also increases the movement resistance of impurity particles in the oil, further reducing its filterability.​

Prone to Form Sediments that Clog Filters​

During the use of phosphate ester hydraulic oil, due to the influence of factors such as temperature, pressure, and oxygen, a series of complex chemical reactions occur, producing various sediments. The components of these sediments are diverse and may include oxidation products, hydrolysis products, additive reaction products, etc. Their particle sizes vary from tiny colloidal particles to larger lumps. Once these sediments accumulate on the filter screen, they quickly clog the pores of the filter screen, resulting in a sharp decline in filtration efficiency. Moreover, due to the strong adhesion between the sediments and the filter screen, it is extremely difficult to clean the filter screen. Special cleaning agents and cleaning processes are often required to remove them.​

Special Requirements for Filter Materials​

Given the above characteristics of phosphate ester hydraulic oil, ordinary filter materials are difficult to meet its filtration requirements. Ordinary filter materials may react chemically with phosphate ester hydraulic oil, leading to a decline in the performance of the materials or even being dissolved. For example, some filter materials containing cellulose will experience swelling, deformation, and other phenomena after coming into contact with phosphate ester hydraulic oil, thereby losing their filtering function. Therefore, filter materials specifically designed for phosphate ester hydraulic oil need to be used. These materials usually have good chemical stability, can resist the erosion of phosphate ester hydraulic oil, and also possess high filtration accuracy and dirt-holding capacity. Common filter materials suitable for filtering phosphate ester hydraulic oil include synthetic fibers, metal fibers, and ceramics. Synthetic fiber materials have high strength and flexibility and can be made into high-precision filter media. Metal fiber materials have good high-temperature and high-pressure resistance and high filtration efficiency. Ceramic materials have excellent chemical stability and corrosion resistance and have a remarkable filtering effect on tiny particles.​
 

Necessity of High-Precision Filtration​

Ensure Stable Operation of Equipment​

For equipment using phosphate ester hydraulic oil, high-precision filtration is the key to ensuring its stable operation. Through high-precision filtration, various impurities in the oil can be effectively removed, reducing the wear and corrosion of hydraulic components caused by impurities, and ensuring the normal operation of key components such as hydraulic pumps, valves, and hydraulic cylinders. For example, in the aerospace field, the hydraulic systems of aircraft have extremely high requirements for reliability. Any minor malfunction may trigger serious safety accidents. By using high-precision filtration devices, particulate impurities in the oil can be controlled at an extremely low level, ensuring that the hydraulic system maintains stable performance in complex flight environments and providing strong support for the safe flight of aircraft.​

Prolong the Service Life of Equipment​

The service life of equipment largely depends on the wear of its key components. Impurities are one of the main causes of wear of hydraulic components. By conducting high-precision filtration of phosphate ester hydraulic oil, the wear of the surfaces of hydraulic components caused by impurities can be significantly reduced, extending the overhaul cycle and service life of the equipment. Take the steam turbine generator units in the power industry as an example. Their speed regulation systems usually use phosphate ester fire-resistant hydraulic oil. If the impurities in the oil are not effectively controlled, it will cause frequent wear of precision components such as servo valves and throttle valves in the speed regulation system, requiring regular replacement and maintenance. However, after adopting high-precision filtration technology, the wear rate of these components can be greatly reduced, reducing the number of equipment maintenance times and costs and improving the overall service life of the equipment.​

Ensure System Control Accuracy​

In many industrial applications, hydraulic systems need to accurately control the movement of actuators to meet the requirements of production processes. For example, in the steel rolling production line of the metallurgical industry, the hydraulic system needs to accurately control the position and pressure of the rolling rollers to ensure the rolling accuracy of steel products. For systems using phosphate ester hydraulic oil, high-precision filtration can effectively prevent the influence of impurities on control components, ensuring that the valve spool can move flexibly and the valves can open and close accurately, thus achieving high-precision control of the system. If there are too many impurities in the oil, it may cause control components to stick or malfunction, reducing the control accuracy of the system and affecting product quality and production efficiency.​

Comply with Industry Standards and Regulatory Requirements​

With the continuous development of industrial technology and the increasing awareness of environmental protection, all industries have put forward higher and higher requirements for the operational safety of hydraulic systems and the cleanliness of oil. Many industry standards and regulations clearly specify the filtration accuracy indicators for phosphate ester hydraulic oil. For example, in industries with extremely high requirements for fire safety, such as coal mining and chemical engineering, relevant regulations require that hydraulic systems must use high-precision filtration devices to ensure that the cleanliness of the oil meets safety standards and prevent fire or other safety accidents caused by oil contamination. Therefore, in order to meet industry standards and regulatory requirements, enterprises must attach importance to the high-precision filtration of phosphate ester hydraulic oil.