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Even when a solenoid valve is designed considering applicable performance criteria and environmental factors, it may not perform properly in service. In order to avoid potential failure modes, a solenoid valve and the system it operates within must be designed properly. Appropriate production processes should be put in place to mitigate the risks associated with common failure modes. Additionally, ensuring the power supply is properly installed and maintained is crucial to prevent solenoid valve failures. Proper installation and maintenance of the power supply help avoid issues related to incorrect voltage levels and electrical supply isolation during maintenance or repairs.
When designing a solenoid valve, the following common failure modes must be considered:
A common failure mode for a solenoid valve is damage that occurs due to contamination, otherwise known as foreign object debris (FOD).
Contamination poses a serious risk to any pneumatic or hydraulic system. Unfortunately, fluids may contain contaminants of various sizes and materials. These contaminants may damage the solenoid valve’s internal components (such as sealing surfaces) or even become lodged inside the valve itself, disrupting the movement of internal components to impact performance overall. In a worst-case scenario, contamination may become trapped in a place that prohibits the solenoid valve components from properly translating, leading to a complete loss of system functionality. One of the most immediate effects is valve failure or malfunction, which can disrupt the entire system’s operation. Common solenoid valve issues related to contamination include valves not opening or closing, leaking, or overheating. Adequate protection against contamination should be incorporated upstream of the solenoid valve.
Contamination in solenoid valves can arise from several sources, each posing a unique threat to the valve’s functionality. One primary cause is inadequate filtration of the fluid being controlled. Without proper filtration, particles and debris can easily enter the system, leading to blockages and damage. Poor maintenance and repair practices also contribute significantly to contamination. Regular upkeep is essential to prevent the buildup of harmful substances.
Incorrect installation or handling of the valve can introduce contaminants, especially if the valve is exposed to harsh environmental conditions. Using incompatible materials or fluids can cause chemical reactions that produce contaminants, further compromising the valve’s integrity. Additionally, failure to follow proper cleaning and storage procedures can leave residues that degrade the valve over time.
Contaminants can infiltrate the valve through various entry points, including inlet ports, outlet ports, vent ports, electrical connections, and gaskets and seals. Ensuring these areas are well-protected and maintained is crucial for preventing contamination and ensuring the longevity of solenoid valves.
The presence of contamination in solenoid valves can lead to a host of severe consequences. One of the most immediate effects is valve failure or malfunction, which can disrupt the entire system’s operation. Contaminants can reduce the valve’s performance and efficiency, leading to increased energy consumption and operational costs. Over time, contamination can accelerate corrosion and wear, causing premature deterioration of valve components.
The risk of electrical shock or short circuits also rises with contamination, particularly if it affects the solenoid coil or other electrical parts. This not only poses a safety hazard but can also lead to significant downtime and repair costs. Contamination can clog orifices and flow paths, impeding the valve’s ability to regulate fluid flow effectively. It can also damage critical components like the armature tube or valve body, leading to more complex and costly repairs.
In severe cases, contamination can cause the solenoid coil to fail, resulting in a complete loss of functionality. Regular maintenance and proper handling are essential to mitigate these risks and ensure the reliable operation of solenoid valves.
Detecting contamination in solenoid valves can be challenging, but several methods can help identify issues early. Visual inspection of the valve and its components is a straightforward approach, allowing for the detection of visible debris or damage. Pressure testing can reveal leaks or blockages, indicating the presence of contaminants. Flow testing is another useful method, as changes in valve performance can signal contamination.
Electrical testing can detect faults or short circuits caused by contaminants affecting the solenoid coil or other electrical components. Once contamination is detected, removing it requires careful cleaning and maintenance procedures. Disassembling the valve allows access to contaminated components, which can then be cleaned using compatible cleaning agents. Damaged or worn components should be replaced to restore the valve’s functionality.
After cleaning and reassembly, the valve should be thoroughly tested to ensure it operates correctly. Regular maintenance and prompt removal of contaminants are crucial for maintaining the performance and longevity of solenoid valves.
Rapid or unexpected pressure fluctuations outside of the solenoid valve’s operating pressure range may cause internal components to move, generating leakage or permanent damage.
It is crucial to ensure that the media pressure does not exceed the maximum pressure rating of the solenoid valve to prevent operational failures.
Certain solenoid configurations incorporate internal components that are not mechanically attached to one another. These configurations are sometimes referred to as “decoupled” solenoid valves. In this scenario, components translate positions with the assistance of system pressure and/or fluid flow. If the system does not provide the required pressure or flow between inlet and outlet ports, internal components may fail to translate appropriately or become otherwise unstable, impacting the valve’s performance and durability. Additionally, aligning the solenoid valve’s flow direction with the system requirements is crucial to ensure optimal performance and functionality.
Figure 1. A two-stage solenoid valve with a detached seal that is de-coupled from the armature.
Figure 2. A two-stage solenoid valve that is coupled to the armature by a screw thread.
If the solenoid coil becomes damaged, it may not be able to generate the required magnetic field to energize and operate the valve. The electrical coil may become overheated from excessive voltage, causing a short circuit or “open coil” condition. It is important to ensure the power supply is compatible with the correct voltage levels to prevent damage to the solenoid coil. Isolating the electrical supply before conducting maintenance or repairs is necessary to avoid electrical shortages. Additionally, the power source may become disconnected or run out of the necessary power. In high vibration settings, an electrical line may be loosened and provide intermittent – or no power at all. Wires, pins, threaded electrical connectors, or plugs, must all be securely fastened to prevent loss of power to the solenoid coil. Incorporating electrical surge protection is crucial to safeguard against voltage spikes that may damage the solenoid coils.
Improper installation of a solenoid valve may lead to significantly degraded performance. The interfaces between electrical inputs and mechanical outputs must be considered in the installation process. Leak paths may develop if the valve’s envelope or internal seals are damaged during the installation process. It is also possible that damage may interfere with the valve’s internal components to further impact performance. Installation instructions should be followed closely to avoid these issues. It is crucial to use the correct solenoid valve to meet system pressure requirements and ensure proper installation.
The solenoid wire and wire termination points may also be fragile. All electrical connections must be secured, or the valve may experience power interruptions. If soldering is required to connect the coil, ensure that proper precautions are taken to eliminate damage to the valve or issues caused by overheating to the coil wire. Ensuring appropriate voltage and current supply for the solenoid coils to function correctly is also significant.
In order to ensure safety within a specific system, many industry associations have documented recommendations or requirements for the validation and verification of solenoid valve performance. Compliance to these specifications is typically required by governing bodies and passed down to suppliers of systems and components. When selecting a solenoid valve, it is important to ensure the valve meets the industry standards required for the application in question. Examples of industry associations that have created guidelines specific to solenoid valve performance are included in the list below:
Regular inspection and testing of the valve can help identify issues early, allowing for timely intervention. It is crucial to inspect the armature assembly during maintenance to ensure proper functioning. Testing the valve after maintenance ensures it functions correctly and meets performance standards. Most solenoid valves require proper electrical connections, voltage specifications, and pressure ratings to prevent common failures. By following these best practices, you can extend the lifespan of solenoid valves and maintain their reliability. Common causes of solenoid valve failure include incorrect voltage, liquid contact, sediment damage, excess water pressure, and temperature changes, making troubleshooting methods essential to mitigate these issues.
The Lee Company designs and manufactures a wide range of valves from miniature plastic pneumatic solenoid valves intended for respiratory therapy applications to high pressure, high temperature hydraulic solenoid valves operating miles underground in oil wells. If you are searching for a valve to meet your needs and would like to learn more about solenoid valves offered by The Lee Company, explore our product finder or contact a Lee Sales Engineer today.
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