Air contamination is one of the most common yet often overlooked problems in hydraulic systems. Whether you are a hydraulic system manufacturer or equipment operator. Understanding the signs of air contamination and how to troubleshoot it is crucial, ensuring your system operates cost effectively. Please read this following article.
3 Types of Air Contamination
Entrained air
Entrained air is small, visible bubbles of air mixed into the hydraulic fluid. It’s usually caused by leaky pipes or loose fittings or poor seals. Air bubbles can cause unstable system operation, like vibration and noise. It can also cause faster wear of components.
Dissolved air
Dissolved air is air mixed in the hydraulic fluid in molecular form. You can’t see it in naked eye. More likely to occur when the hydraulic fluid is under high pressure or elevated. When the pressure suddenly drops. This air can escape from the oil, forming bubbles. This can degrade the fluid’s performance.
Free air
Free air refers to large bubbles, or pockets of air trapped in the hydraulic fluid. Usually visible to your naked eye.
Signs of Air Contamination in Hydraulic Systems
Bubbles in Hydraulic Oil
This phenomenon is the most obvious sign of air contamination. A layer of persistent foam will cover the surface of the oil. It is difficult to dissipate quickly. Also, you can see bubbles of varying sizes. They suspended or rising within the oil.
Abnormal Hydraulic Oil Color
A change in hydraulic oil color is also a typical sign of air contamination. Normal hydraulic oil should be clear and translucent. Depending on the type, it may appear light amber or red. When air enters the oil. It gradually loses its transparency and becomes cloudy. The color may darken or even take on a grayish hue. The oil’s appearance becomes less pure. Giving it an emulsified appearance.
Noise
Pumps and valves may generate abnormal noises while in service. A noise looks like cavitation heard near the machinery. It is usually a result of bubble collapse under high pressure. The noise can sound is that high pitched or goes off and on. Very different than the normal sound.
High Temperatures
Rising system temperatures are also a noticeable sign of air contamination. When air mixes with hydraulic oil. It impairs the fluid’s flow through the system. Then reducing the energy transfer efficiency. This increases friction between hydraulic components. Also increases the turbulence associated with the oil flow. It causes the system to gradually heat up. Reaching temperatures significantly above normal.
Unstable Hydraulic Machinery Operation
The flow rate in the system may fluctuate suddenly. This can cause discontinuous and uneven movement of the pump or motor or hydraulic cylinder. During operation, the machinery may move faster and slower. Or even pause or jump. This can cause the entire hydraulic system to appear noticeably unstable.
Actuator Insensitivity
When actuators experience air contamination. Fluid pressure may be difficult to maintain. When a hydraulic cylinder or other actuator operates in response to an operating command. You may notice a significant increase in the actuator’s response time. Actuation may become out of sync with the control signal. Result in insensitive operation and delayed movement.
Pressure Fluctuations
When air mixes with hydraulic oil. The system may experience noticeable pressure fluctuations. Air bubbles in the oil will continuously compress, and expand in high pressure areas. Then causing the system’s internal pressure level to become unstable. When you observe on a gauge. The pressure indicator or digital display will fluctuate frequently. The pressure reading will not be stable.
Solutions for Preventing and Addressing Air Contamination
Improving Sealing Performance
If there is poor sealing at various joints in a hydraulic system. It can easily lead to air being drawn in during operation. You should regularly inspect the seals. Ensuring they are free of signs of wear or cracks or deterioration. You should also ensure they are correctly positioned and tightly fitted. If any seals are found to be defective. They should be replaced promptly. Preventing air from entering the system through minor gaps.
Ensure the Correct Oil Level
If the hydraulic oil level is too low. The hydraulic pump may be partially exposed to air during operation. This can cause air inhalation and lead to cavitation. To prevent this problem. You must regularly check and monitor the oil level in the tank. Ensure it remains within the correct range. If the oil level is low, you should promptly add the appropriate hydraulic oil. Maintain a stable operating environment for the system.
Ensure Oil Quality
Hydraulic oil deteriorates over time due to exposure to high temperatures or humidity. This can manifest as decreased clarity and even reduced performance. If you continue use degraded oil. It will increase the risk of air bubbles forming and air intrusion. Therefore, it’s important to use standard quality hydraulic oil. You should replace it at the prescribed intervals. When replacing or refilling, ensure the operating environment is clean.
Use a Respirator and Air Filtration System
Install a respirator or vent cap at the fuel tank’s vent opening. This prevents dust and moisture from entering the fuel tank during air exchange. Effectively blocks impurities and dries the incoming air. You should regularly check the respirator and filter element. And replace it according to usage, to maintain filtration effectiveness.
Using Air Separator and Degassing System
This method effectively removes air that has been mixed or dissolved in hydraulic oil. An air separator typically has a flow chamber. This slows the oil flow as it passes through it. Air bubbles rise within the chamber. Reaching the surface and separating from the oil. They are then discharged from the system. Degassing systems often use a vacuum chamber or other low pressure device. By reducing the pressure of the hydraulic oil. The dissolved air is extracted from the oil and discharged. This method is suitable for handling small amounts of entrained air.
Conclusion
Through the introduction of the above article. I believe you have a clearer understanding of the common signs of air contamination, and you could control the prevention and treatment methods. If you want to know more, contact us.
FAQ：
What are the possible causes of air contamination in hydraulic systems?
There are many causes for this. If the seal is worn or damaged or deteriorates due to not being replaced for a long time. It will lose its sealing effectiveness. Then air can easily enter the system through connections. When a pump operates below the vapor pressure. Bubbles then form and collapse under high pressure. Then causing air to enter the oil. A low fluid level is also a common reason. This make air sucked into the pump. It also may cause oil turbulence. Exacerbating air contamination.
What are the differences between entrained air & dissolved air?
You can see entrained air as small bubbles. It has the power to make oil cloudy or frothy. Directly affecting the system to run smoothly. Dissolved air as molecules. You can’t directly see it. It produces bubbles only at the point of rapid decompression.
