Ensuring the safety and efficiency of air bellows in hydraulic systems is paramount. At Tevema, we prioritize the integrity and performance of our air springs through meticulous design and rigorous safety protocols.
Installation and Operation
Proper installation is crucial for the optimal performance of air bellows. We recommend the following steps:
- Pressure Management: The maximum allowable pressure for standard air springs is 8 bar. For higher pressures, consult with us for a four-ply construction option, which can handle up to 12 bar. This ensures that the air springs can operate safely under varying conditions without risking damage or failure.
- Return Mechanism: Air springs are single-acting actuators and should not be used below atmospheric pressure. Ensure external loads manage the return operation. This is critical to prevent the air springs from collapsing or malfunctioning, which could lead to system failures or safety hazards.
- Working Media: While designed for compressed air, our air springs can also operate with nitrogen, oil, water, and air containing oil. For water applications, use stainless steel parts to prevent corrosion. This versatility allows our air springs to be used in a wide range of applications, enhancing their utility and reliability.
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Safety Stops and Support Area
To prevent overextension or bottoming out, incorporate safety stops. Ensure the air bellows are pressurized only when restricted by a suitable load or stop. Utilize the complete area of the rubber actuator for uniform load distribution, or at least 65% of the support area. This helps in maintaining the structural integrity of the air springs and prevents uneven wear and tear.
Installation Space and Elastomer Compound
Position the air bellows correctly, ensuring no sharp materials can damage them. The elastomer compound used in manufacturing varies based on application requirements:
- Natural (NR/SBR): -40° to +70°C. This standard material offers excellent universal properties and high dynamic capability, making it suitable for a variety of applications.
- Clorobutyl (CIIR): -30° to +115°C. Known for its outstanding resistance to acids, this material is ideal for environments where chemical exposure is a concern.
- Nitrile (NBR): -25° to +110°C. This compound provides excellent resistance to oils, fuels, ozone, and outdoor conditions, making it highly durable in harsh environments.
- Ethylene Propylene Diene (EPDM): -20° to +115°C. With excellent resistance to high temperatures, ozone, and outdoor conditions, EPDM is suitable for applications requiring long-term durability.
- Chloroprene (CR): -20° to +110°C. This material offers excellent weather resistance and medium resistance to oils, making it versatile for various industrial applications.
Metallic Parts and Auxiliary Reservoir
Our air bellows come with electro-galvanized steel parts, with options for stainless steel AISI-304 and AISI-316L for high resistance to acids and chemicals. Adding an auxiliary reservoir can improve isolation rates by increasing volume and decreasing natural frequency. This enhancement is particularly beneficial in applications requiring precise vibration isolation and stability.
Stability and Height of the Center of Gravity
For optimal stability, the distance between the narrowest point of the mounted air bellows should be at least twice the height from the center of gravity. Stability can be enhanced by widening the base, elevating the mounting location, or adding an inertia base. These measures help in minimizing wobbling and optimizing the isolation performance of the air springs.
Lateral Misalignment and Stiffness
Air actuators can accommodate lateral misalignments depending on their size and construction. For vibration isolation, use air springs at their design height to achieve maximum lateral stability. The lateral stiffness varies based on the number of plies, height, and pressure, with single convolution and double convolution air springs offering different levels of lateral stability.
Angular Capability
Air bellows can tilt up to 25°, depending on the number of convolutions. Ensure the highest point is below the maximum height and the lowest point is above the minimum height to avoid chafing. This angular capability allows for flexibility in installation and operation, accommodating various system configurations and movements.
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Angular Capability of Air Bellows
Definition: Angular capability is the maximum angle at which an air bellow can tilt without compromising its performance or structural integrity.
Factors Influencing Angular Capability
- Number of Convolutions: The design of the air bellow, specifically the number of convolutions (folds), significantly affects its angular capability.
- Single Convolution Bellows: These can typically tilt between 10° to 15°.
- Double Convolution Bellows: These offer greater flexibility, with a maximum tilt angle of up to 25°.
- Triple Convolution Bellows: These can tilt up to 15°, but they are generally used for vibration isolation with lateral guidance due to their lateral instability.
- Height and Stroke: The tilt angle is also dependent on the height of the air bellow and the stroke (the distance the bellow can extend or compress).
- Highest Point (h2): This must be lower than the maximum height of the air bellow.
- Lowest Point (h1): This must be higher than the minimum height to avoid chafing and ensure smooth operation.
Practical Considerations
- Avoiding Chafing: When the air bellow tilts, the most compressed part can rub against other components, leading to wear and tear. Proper design and installation can mitigate this risk.
- Combining Misalignments: It is not advisable to combine angular misalignment with lateral misalignment, as this can lead to excessive stress on the air bellow and potential failure.
Applications
The angular capability is particularly useful in applications where the air bellows need to adapt to dynamic conditions, such as:
- Vehicle Suspension Systems: Where the air bellows must accommodate the tilting and movement of the vehicle.
- Industrial Machinery: Where components may shift or tilt during operation, requiring the air bellows to maintain stability and support.
By understanding and utilizing the angular capability of air bellows, we can design more robust and adaptable hydraulic systems that perform reliably under various conditions.
Maintenance and Inspection
Regular maintenance is essential for long-term performance. Clean the rubber bellows with water, soap, or alcohol, avoiding abrasives and organic solvents. Inspect for wear, cracks, and damage, and check pneumatic components for replacement needs. Proper maintenance ensures the longevity and reliability of the air springs, preventing premature failures and costly downtime.
Conclusion
By adhering to these safety measures, we ensure the reliability and longevity of air bellows in hydraulic systems. At Tevema, we are committed to providing high-quality solutions tailored to your needs. Our expertise in air springs and dedication to safety and performance make us a trusted partner in the industry.