Whether you’re a mechanical or electrical engineer or the senior purchasing manager at a major manufacturing facility, you’re likely familiar with solenoid valves and their role in the flow of liquids and gases. But when a solenoid valve begins to malfunction, you may not be equipped to deal with the many issues that may arise.
There are various applications of solenoid valves including heating systems, industrial automation, swimming pools, sprinkler systems, washing machines, dental equipment, car wash systems, and much more.
Solenoid valves can also be used for many types of protection systems such as emergency shutoff systems and fire protection applications. For example, solenoid valves can be used in conjunction with electric fire detectors. Once a fire is detected in a building, an electric current energizes the solenoid valve, thus, allowing the orifice – from which water flows – to open and activate a sprinkler system. This helps keep the fire under control and prevent spreading to other parts of the building.
Solenoid valves must be of good quality and meet Safety Integrity Level (SIL) standards. These standards are set to reduce the risk posed by processes to people, the environment, and property. To do this, operators must be familiar with failure probabilities for everything to sensors to controllers and actuators for the entire service life of the components. Operators must also use suitable devices that have either been evaluated or certified. Regular tests and inspections must be performed to ensure correct observation of safety functions.
The higher the SIL of a safety-related system, the lower the probability of the system not being able to execute the necessary safety functions.
Below are some of the common challenges operators face with solenoid valves and how to combat them.
Leakage in solenoid valves is either classified as internal or external.
Internal leakage, or seat leakage, occurs when the fluid passes between the valve seat and the sealing member when the valve is in a closed position. This type of leakage is often caused by foreign materials in the process medium. When particles in the medium become trapped between the seat and the sealing disc, a gap or cut in between the parts is created. The leakage typically starts off small and can escalate to a high leakage rate depending on the process fluid and pressure of the fluid. Due to the liquid traveling at high velocities through the leakage path, it can erode the sealing surface.
To eliminate leakage caused by foreign materials, operating the valve for a few cycles with fluid pressure can dislodge or flush the material and allow the valve to seal properly again. Other causes of internal leakage include improper assembly of valve parts and misapplication of a valve. These problems can be solved by taking off the parts and reassembling them according to the manufacturer’s instructions and working closely with the manufacturer by giving them all the technical details needed for a suitable valve.
External leakage is generally caused by degraded O-ring seals, which either stems from incorrect installation or regular usage. This problem can usually be fixed by installing a new O-ring. Using diaphragms as sealing members can also cause external leakage. This happens because pressurized fluid goes through the diaphragm material between the rubber and reinforcing material of the diaphragm in a process called wicking. Using a non-reinforced diaphragm (or solid diaphragm) or using anti-wicking compounds of the diaphragm material can eliminate wicking.
If the valve is still leaking after applying the solutions mentioned above, a closer look is required to find the source of the problem. Follow the manufacturer’s instructions to disassemble the valve. Ensure that all sealing surfaces and pilot passageways are clean and clear of any foreign materials. Check the seat for any cuts or erosion. If the disc is nicked or eroded, check the body for nicks or erosion as well. If this is the case, contact the manufacturer for replacement parts. If leakage still occurs, you may need to install a new valve or change your valve construction altogether.
Below are the common reasons a solenoid valve does not open:
Just as valves have problems opening, they can also fail to close, which can be caused by a manual override, pressure difference, residual coil power, etc. If your solenoid valve is partly closing, it’s important to check wirings, lead connections, components and diaphragm.
An overheated solenoid coil will “burn out” or short. Coils within the solenoid valves can burn out for a variety of reasons:
When it comes to installing a solenoid valve, it’s important to select the right solenoid framework for various protection systems. Engineers and buyers can trust Johnson Electric to provide the highest quality solenoids for the task. Contact us for more information.