The hydraulic valve is part of the hydraulic system that controls the speed and direction of fluid flow. The hydraulic system goes dead when a hydraulic valve fails. This article will tell you the common problems of hydraulic valves and the corresponding solutions, and how to maintain the hydraulic valve.
Signs of Hydraulic Valve Failure
Hydraulic valve failures do not occur suddenly, they usually give you some warning signs. If your hydraulic valve experiences fluid leakage, reduced efficiency, or loss of function during daily use, it is likely experiencing an issue. At the same time, these three signals are also warning you:
Abnormal Noise: When abnormal noise occurs in a hydraulic valve, it may indicate cavitation. This means the presence of air bubbles in the fluid, which causes contamination. Another possibility is that a component of the hydraulic valve is damaged or misaligned, causing the abnormal noise.
High Temperature: High temperature is also a critical indicator that the hydraulic valve is about to be broken. If the fluid temperature is excessively high, it may surpass the operating temperature limit of the hydraulic valve, potentially causing component damage or fluid decomposition. Excessive environments can also degrade the performance of seals, ultimately leading to fluid leakage.
Delayed Response: If your hydraulic system is responding slowly and operating erratically, it may be that the hydraulic valves are malfunctioning. Fluid contamination or a stuck valve core can both affect the operational efficiency of the system.
Common Issues and Reasons of Hydraulic Valves
Hydraulic valve failures can be basically classified into mechanical and electrical reasons. Failures of mechanical valves primarily occur in hydraulic components of the valve, such as valve size, wear of seals, or damage to the spool. However, voltage problems are the main reason for the electric valve failures. Typical electrical failures are low voltage of solenoid valve, bad connection due to port damage, and wrong voltage of electrical valve. Below are common issues and potential causes for different types of hydraulic valves.
Pressure Control Valves
Pressure control valves are the most common valves in hydraulic systems, playing a crucial role in preventing fluid leakage and other functions. The problems that might happen to pressure control valves with different functions are not exactly the same.
Pressure Relief Valves
If the spring valve and spool in a pressure relief valve are separated or damaged, pressure goes down, and it is not stable. Broken or weak springs can result in an excessively high system pressure. Particles in the fluid that block the balance orifices of the relief valve are another cause. It can even release the pressure relief valve in the most extreme cases.
The pressure relief valve may generate abnormal noise if an incorrect pressure value is set in advance before use of the press relief valve, or the fluid is very thick. When this pressure relief device was not working, or if the valve seat was leaked, the system temperature became higher than normal. A relief valve is susceptible to failure if it gets too hot out.
Pressure Reducing Valves
Unstable pressure is one of the most common problems in hydraulic pressure reducing valves, and there may be various causes for this malfunction. Factors such as fluid contamination, valve seat wear, and valve spool jamming can all lead to unstable pressure in the pressure reducing valve. Using incorrect springs is also a reason.
Sequence Valves
There are many reasons that lead to the failure of the sequence valve, such as the fracture of the spring, gasket leakage, gasket damage, pipeline is blocked, piston failure and so on. The sequence valve has a strict working process and will only start the secondary operation after the main operation is completed. You may encounter the phenomenon that the secondary operation of the sequence valve starts too early. This is due to the primary cylinder bearing an excessively high inertia load, or because the pressure setting value is too low.
Directional Control Valves
Directional valves often experience incomplete displacement, which may be due to the failure of the centering spring or the wear of the linkage. Insufficient pilot pressure can also affect the control valve. If the spring breaks, the relief valve leaks, or the valve spool shifts position, then cylinder load may drop.
Solenoid actuated valves are also a type of directional control valves. Due to the relatively high rated pressure required for solenoid actuated valves, they feature a multi-seal structure. However, the lifespan of these gaskets is limited, and they are prone to aging or wear, leading to fluid leakage. If the fluid temperature is too high or it contaminates the components of the solenoid valve, it will cause damage to the electronic components.
Flow Control Valves
Flow control valves include ball valves, butterfly valves, diaphragm valves, needle valves, etc. In hydraulic applications, they manage the liquid flow. Some of the flow control valves have the defect that it is liable for the flow volume to fluctuate. There could be a couple of reasons, but the typical ones are the valve core is stuck, or the cylinder is leaking. The fluid pressure and viscosity are also closely related to the fluid flow fluctuations.
Pressure may be uneven in case the valve core or valve seat wear or the fluid is dirty. So, when you notice the reading on the pressure gauge is inconsistent, you may have issues in these areas. Another problem for flow control valves is sluggish flow. This could be the result of pressure relief valve leaking and outlet hole too small or valve piston warping.
Solutions of Hydraulic Valve Failures
Diagnostic Methods
Before you do anything about your hydraulic valve, you will need to determine what’s wrong. Visually check the hydraulic system to see if there is any leak, corrosion, or mechanical damage. Next, inspect the hydraulic valve pressure. If the pressure is too low, the fluid may have leaked. If the information on your pressure gauge is always going back-and-forth, it might be telling you that the valve core is faulty.
At the same time, the state of the fluid should also be checked. If the oil is too dark in color or even has a burnt smell, it indicates that the temperature is too high. If the fluid appears cloudy or contains metal particles, it means contamination or wear in the hydraulic valve components. If conditions permit, you can use sensors to further filter out issues.
Repair Measures
Once you diagnose the issue, know what you can do to fix it. If the hydraulic valve components are at fault, use tools to repair. However, replacing hydraulic valve components can prevent the same problem in the future. If there is a problem with the fluid, you can clean it with filtration or with chemicals. If none of these techniques do the trick, try a new or different fluid. Moreover, while using hydraulic valves, it is crucial to set the appropriate pressure and maintain the equipment periodically.
How to Extend Valve Lifespan
When choosing hydraulic valves for a hydraulic system, keep in mind such important factors as materials, operating pressure, and fluid types to ensure smooth performance of the hydraulic valve within the entire hydraulic system. Not only does this prolong the service life of the valves, it also increases Operation efficiency.
The most effective method to extend the service life of hydraulic valves is preventive maintenance. Regularly inspect valve components for wear and promptly replace damaged parts. Ensure fluid safety and maintain pressure within normal operating ranges at all times.
Conclusion
Hydraulic valve failures manifest in multiple ways, and different types of hydraulic valves may exhibit distinct issues. Addressing these problems specifically is a crucial method for maintaining the stability of hydraulic systems. If you have any other questions regarding hydraulic valves, feel free to contact us anytime.
FAQ
1. Does a malfunctioning hydraulic valve always need to be replaced?
If the failure is caused by contamination or blockage of the hydraulic valve, or minor wear on the valve spool, you can repair it to restore the functionality. However, if the hydraulic valve itself suffers severe irreversible damage, you must replace it with a new one to prevent further losses.
2. What impact does hydraulic oil have on the hydraulics valves?
If the hydraulic fluid is mixed with water or impurities, it can cause many components failures in the course of a system run, and reduce the service life of the hydraulic valve. You can also tend to destroy hydraulic valves with inappropriate oil type so it is better to go for the type recommended by the manufacturer.
