Comparing the handling methods of hydraulic and pneumatic media

Medium: the carrier of energy transmission

Whether in pneumatic or hydraulic systems, the medium serves as the carrier of energy, transmitting pressure or force to enable the actuator to perform mechanical motion.On factory production lines, pneumatic actuators are often relied upon to carry out fast assembly operations, while on construction sites, excavators, elevators, and automobile braking systems depend on hydraulic technology to transmit enormous power.

Clearly, the structures of the two types of actuators are very similar, and the primary factor that leads to the difference in pushing and pulling forces between the two is the pressure of the medium. The pressure of pneumatic cylinders typically ranges from 0.4 MPa to 1 MPa, while the pressure of hydraulic media is usually between 5 MPa and 35 MPa, and can even reach 70 MPa or higher in some high-pressure applications. This difference in pressure results in different mechanical forces, including output and return forces, between the two systems.

For both pneumatic and hydraulic components, maintenance and lubrication start with the treatment of the fluid medium. While the components and types of fluid media are different for these two systems, the maintenance and care processes for both pneumatic and hydraulic components are the same. This includes treating the medium with processes such as drying, dewatering, lubrication, and filtration.

Media processing methods between hydraulic and pneumatic

Medium Lubrication

Whether in pneumatic or hydraulic systems, lubrication is key to ensuring the proper functioning of components, reducing wear, and improving efficiency.

• Hydraulic System: Hydraulic oil itself usually has some inherent lubrication properties, helping to reduce friction between the piston, piston rod, pump, and other action components. Therefore, the treatment for hydraulic systems involves regularly checking the oil quality to maintain its lubrication effect.

• Pneumatic System: Lubrication in pneumatic systems is usually achieved by adding a dedicated oil mist device to treat the compressed air. Through the conduction of the fluid medium, it provides lubrication to components such as pneumatic cylinders and valves, so there is no need for separate disassembly or treatment.

Medium Filtration

Filtration is essential for removing impurities, dust, moisture, and other contaminants from the fluid, preventing them from damaging system components.

• Hydraulic System: Filtration of the hydraulic oil is crucial, as any contaminants entering the system can cause wear or clogging of pumps, valves, hydraulic cylinders, and other components.

• Pneumatic System: Filtration in pneumatic systems addresses impurities such as moisture, oil mist, and dust in the compressed air. The filters used in compressed air systems typically include three types: coarse filters, medium-efficiency filters, and precision filters, each with varying capabilities for removing different types of contaminants.

Medium Drying and Dehydration

Maintaining the dryness of the medium is critical for the proper function of other components, especially metal parts, in both pneumatic and hydraulic systems.

• Hydraulic System: Water in hydraulic oil reduces the oil's lubricating properties, causes degradation, and can result in corrosion or freezing issues. Therefore, treatment for hydraulic oil involves using water separators and dehydration devices.

• Pneumatic System: Compressed air can easily carry moisture, which not only affects system lubrication but can also lead to rust and damage to pneumatic components. An air dryer is used to treat the pneumatic system's medium.

Medium Replacement and Addition

Over time, both hydraulic oil and compressed air may gradually fail to meet quality and pressure requirements.

• Hydraulic System: Hydraulic oil undergoes oxidation and decomposition with extended use, which reduces its pressure transmission effectiveness. Therefore, hydraulic system fluids need to be periodically replaced, and the cleanliness and purity of the oil should be checked.

• Pneumatic System: Compressed air does not need to be regularly replaced, but it requires periodic filtration, drying, and lubrication treatment to ensure its quality.

Medium Transmission in Hydraulic Systems

Hydraulic oil is incompressible, allowing efficient transmission of large and stable power.
Hydraulic pipes and fittings must be resistant to high temperature and high pressure, ensure leak-free transmission, and allow easy assembly and maintenance.

Medium Transmission in Pneumatic Systems

Air is compressible, so attention must be paid to pressure stability, the presence of impurities, and reliable sealing during transmission.

Since compressed air operates at relatively low pressure, fittings are usually made of plastic or lightweight metal. Push-in and quick-connect fittings are commonly used to enhance the flexibility of system piping desig

Other Maintenance Methods for System Components

Regular Inspection and Replacement of Seals

Both pneumatic and hydraulic systems require the inspection of seals in actuators, valves, pumps, and other components to ensure proper sealing. Worn or damaged seals should be replaced promptly to maintain system efficiency and prevent leakage.

External Moving Components of Actuators

Pneumatic and hydraulic actuators often have external moving parts, such as piston rods, guide rods, and mounting devices. These components should undergo regular reinforcement treatment to prevent wear and ensure smooth operation.

Regular Cleaning and Removal of Carbon or Contaminants

Dirt or other contaminants often accumulate in the piping system. These particles can significantly impact the system's ability to transport the working medium, so regular cleaning is essential to maintain system performance.

Control and Maintenance of Operating Temperature

Excessively high operating temperatures can accelerate the degradation of hydraulic oil or pneumatic lubricating oil, reducing lubrication effectiveness and causing component wear. Therefore, it is crucial to maintain the pneumatic and hydraulic systems within their normal working temperature range.

Fokca:Production base for pneumatic and hydraulic products