Gel Formation in Hydraulic Fluid: Causes, Impact, and Solutions

[MikePhua]

Hydraulic systems are integral to many heavy machines, ranging from excavators and cranes to forklifts and agricultural equipment. These systems rely on hydraulic fluid to transmit power and enable smooth operation. However, one issue that can arise in hydraulic systems is the formation of gel in hydraulic fluid. This problem can significantly impair the efficiency and performance of the system. In this article, we’ll explore the causes of gel formation in hydraulic fluid, its impacts on equipment performance, and the steps that can be taken to address it.
Understanding Hydraulic Fluid and Its Role
Hydraulic fluid serves several key purposes in hydraulic systems:

• Transmission of Power: It helps transfer force within the hydraulic system, allowing machines to operate with high efficiency.
  
• Lubrication: Hydraulic fluid lubricates various components within the hydraulic system, reducing friction and preventing wear.
  
• Cooling: It helps regulate the temperature of the hydraulic system by dissipating heat produced during operation.
  
• Contaminant Removal: The fluid also helps flush out contaminants, keeping the system clean.
  

Given the variety of functions hydraulic fluid performs, its quality and condition are crucial to the machine’s overall performance. Any issue that affects the fluid’s integrity can lead to significant operational problems, such as gel formation.
What is Gel in Hydraulic Fluid?
Gel in hydraulic fluid refers to the thickening or solidification of the fluid, which impairs its ability to flow freely through the system. This condition typically occurs when additives or contaminants in the fluid react in a way that causes the fluid to become viscous or "gel-like."
In extreme cases, gel formation can block the flow of hydraulic fluid through filters and valves, which in turn reduces the system's ability to generate power and perform effectively. This can result in sluggish operation, excessive wear, and, in some cases, complete system failure.
Causes of Gel Formation in Hydraulic Fluid
Gel formation in hydraulic fluid can result from various factors, including:

1. Temperature Extremes:
   Hydraulic fluids can gel when exposed to extremely cold temperatures. Many hydraulic fluids are designed to remain liquid within a specific temperature range. However, when the temperature drops significantly, the fluid may thicken and form gel-like substances. This can occur in equipment used in cold climates or during winter months when ambient temperatures drop below the fluid’s designed operating temperature.
   
2. Contaminants in the Fluid:
   The presence of contaminants, such as dirt, water, or even metal particles from worn-out components, can alter the chemical composition of the hydraulic fluid. These contaminants can cause the fluid to react and form gel-like substances. Water contamination, in particular, can lead to the formation of emulsions that thicken the fluid.
   
3. Chemical Additive Imbalance:
   Hydraulic fluids often contain various additives to improve their performance, such as anti-wear agents, rust inhibitors, and stabilizers. If the balance of these additives is disrupted, for example, due to improper storage or mixing of different fluids, it can lead to gel formation. Additives designed to improve the fluid’s stability at high temperatures can also cause the fluid to thicken if they are incompatible with other components in the fluid.
   
4. Improper Fluid Compatibility:
   Mixing different types of hydraulic fluid, or using a fluid that is not compatible with the machinery’s requirements, can result in gel formation. For example, mixing mineral oil-based fluids with synthetic fluids can cause undesirable chemical reactions that lead to thickening or gel formation.
   
5. Aging of Hydraulic Fluid:
   Over time, hydraulic fluid breaks down due to constant exposure to heat, air, and contaminants. When the fluid ages and degrades, it can form sludge and gel-like substances. Regular fluid maintenance and replacement are essential to prevent the system from becoming clogged or compromised.
   

Impacts of Gel Formation on Hydraulic Systems
When gel forms in hydraulic fluid, it can have several detrimental effects on the performance of the machinery:

1. Reduced Fluid Flow:
   Gelled hydraulic fluid becomes thick and sticky, preventing it from flowing freely through the system. This leads to increased resistance, which reduces the system’s efficiency and may cause it to operate sluggishly or even stall altogether.
   
2. Increased Wear and Tear:
   Gel formation can cause components such as pumps, valves, and cylinders to operate under higher stress levels. The thickened fluid can impede smooth lubrication, leading to increased friction and accelerated wear on key parts. This can cause premature failure of critical components and the need for costly repairs.
   
3. Overheating:
   The inability of the fluid to circulate properly can cause the hydraulic system to overheat. When fluid does not flow adequately through the system, heat is not dissipated effectively, leading to elevated temperatures that may damage the fluid and the equipment.
   
4. Clogged Filters and Lines:
   Gel formation can clog the filters, hoses, and valves of a hydraulic system. This reduces the fluid’s ability to pass through the system’s filtration and circulation systems, which can cause pressure buildup and lead to further damage.
   
5. System Failures:
   In the worst-case scenario, gel formation can cause complete failure of the hydraulic system. If the fluid becomes too thick to pass through critical components like the pump or valves, the machinery will be unable to function.
   

Preventing Gel Formation in Hydraulic Fluid
Preventing gel formation in hydraulic fluid requires a proactive approach. Below are some effective measures to ensure that hydraulic fluid remains in optimal condition:

1. Use the Right Fluid for the Environment:
   Ensure that the hydraulic fluid is appropriate for the climate and operating conditions. For colder climates, choose fluids with additives that prevent gelling at low temperatures. Many manufacturers offer winter-grade fluids that are designed for low-temperature applications.
   
2. Regular Fluid Maintenance:
   Regularly check the condition of the hydraulic fluid. If the fluid appears cloudy, dark, or thickened, it may be time to replace it. Monitoring the fluid for contaminants like water or dirt is essential, as these can accelerate gel formation.
   
3. Proper Storage:
   Store hydraulic fluid in a clean, dry, and temperature-controlled environment to prevent contamination and degradation. Avoid storing fluids near sources of heat, as prolonged exposure can cause them to break down faster.
   
4. Routine System Cleaning:
   Perform regular cleaning of hydraulic systems, including flushing out old fluid and replacing filters. This helps maintain the fluid’s integrity and ensures that no contaminants are present that could contribute to gel formation.
   
5. Monitor and Maintain Additives:
   Use only high-quality hydraulic fluids with the correct additives for your equipment. Make sure to check the compatibility of different additives and avoid mixing incompatible fluids.
   

Dealing with Gel Formation in Hydraulic Fluid
If gel formation has already occurred in a hydraulic system, it is important to address the issue quickly to minimize damage. Here are steps to deal with gel in hydraulic fluid:

1. Flush the System:
   Flushing the hydraulic system is often the first step in clearing gelled fluid. This process involves removing the contaminated fluid and replacing it with fresh fluid to restore proper circulation.
   
2. Replace Clogged Filters and Hoses:
   If filters or hoses have become clogged with gel, they should be replaced to restore normal fluid flow. Clogged filters can cause significant pressure buildup, which can damage the hydraulic components.
   
3. Use a Fluid Conditioner:
   In some cases, a fluid conditioner or additive may be used to break down the gel and return the fluid to its original consistency. However, this is a temporary solution, and the fluid should still be replaced as soon as possible.
   

Conclusion
Gel formation in hydraulic fluid can cause serious operational problems, from reduced performance to total system failure. Understanding the causes of gel formation, such as temperature extremes, contaminants, and improper fluid compatibility, can help prevent it from happening. Regular maintenance, proper fluid management, and system cleanliness are essential to keeping hydraulic systems functioning efficiently. By taking proactive measures, operators can ensure the longevity and reliability of their equipment.