Introduction
Electro-hydraulic servo valves (EHSV) are widely used in the control of fluid flows in various applications in industry. An EHSV valve is essentially an on / off valve controlled electrically. It has the ability to quickly shift into one of two positions: either open or closed. In an EHSV, the opening / closing action is performed under the control of an electric current applied to the actuator served by a set of copper or steel coils. In theory, EHSV valves can be designed to produce extremely precise output, and the actuation can be done either manually or by means of a remote control.
One of the most significant advantages of EHSV valves is that they can operate in the presence of large pressure ranges or high temperatures and still maintain the required level of accuracy. However, like any other type of valves, EHSVs can develop malfunctions due to several factors. The purpose of this paper is to discuss the potential causes of EHSV failure and the solutions available in order to prevent or lessen the impact of such failures.
Factors Affecting the Reliability of EHSV Valves
The majority of EHSV failures are due to issues related to design and fabrication, with the most common being material fatigue, wear, corrosion and inadequate lubrication. Improper installation of the valve, inadequate maintenance strategies and the application of excessive pressure can also lead to EHSV failure. In addition, there is the possibility of reverse bending stress in the valve, which can occur due to thermal or pressure stresses acting on the valve body or its components. Lastly, there is the possibility of a voltage pulse supply as a cause, either due to the presence of excessive energy or insufficient power.
Solutions for EHSV Valve Failure
Given the various potential causes of EHSV failure, there are various solutions available to reduce the risk and impact of such failures. It is important to understand that the best solutions to preventing such failures are to ensure proper design of the EHSV valve and its components and to ensure a high quality of fabrication standards. This requires a thorough understanding of the unique requirements of the application.
Design and fabrication
There are certain design considerations that must be taken into account in order to ensure the reliability and longevity of an EHSV valve. One of the most important is to use materials that are specifically suited to the application and are resistant to corrosion and wear. In addition, the valve must be designed to handle the expected pressure, temperature, and flow rate. The valve design should also include the use of adequate lubrication and corrosion protection systems, as well as the use of adequate seal types to ensure a tight seal between the valve and the hose or pipe it connects to.
It is also important to ensure that the fabrication of the valve is completed according to the specified design. This includes using the correct number and size of parts, proper installation of components and correct connection of the various parts.
Maintenance strategies
In order to ensure that an EHSV valve remains in good working condition, it is important to establish a maintenance program. This should include regular checks and tests that are necessary to ensure the correct operation of the valve. In addition, proper lubrication and the cleaning of filter elements should be performed on a periodic basis. Regular inspection of the valves should also be done to check for any signs of wear or corrosion. In the event that a malfunction is detected, it should be addressed immediately in order to reduce the potential of further damage.
Conclusion
This paper has discussed the potential causes of failure in EHSV valves and the solutions available to reduce the risk and impact of such failures. As with any other valve, it is important to ensure that the design and fabrication are completed to a high standard and that a proper maintenance program is in place. Additionally, it is important to monitor the performance of the valve and to raise the alarm should any potential failure be detected. If done correctly, an EHSV valve can provide many years of reliable service in various applications.
