Solenoid valves are designed to be efficient and durable. But with moving parts, these devices are prone to breaking down at any time. Some, like the solenoid ball valve, require an actuator that further complicates the assembly.
Reasons for faults vary depending on the type of solenoid valve and application. It can be an under or over-voltage, wrong valve capacity, impurities in the media, pressure drop, wrong material, or just bad installation.
To diagnose a malfunctioning solenoid valve, here are the common faults or problems to look out for.
1. Solenoid Valve Not Opening
A solenoid valve should open when it’s required to.
If it doesn’t, it means there is a fault somewhere. It could be insufficient voltage across the wire leads of the solenoid valve coil, which is usually termed as power failure.
Without enough current to energize the coil, the force needed to open the orifice cannot be attained, leading to the valve failing to open.
It could also be the solenoid not receiving any current whatsoever. This can be caused by bad connections at the source or even failure of the solenoid controller module.
A faulty coil will likewise lead to valve failure and show up as a valve orifice that won’t open even when the various components seem to be working correctly.
Another cause of solenoid valve not opening include dirt or debris under the valve’s diaphragm. This often happens when the media flowing through contains impurities. Miniature solenoid valves are more prone to this problem.
Corrosion can also lead to jamming of the valve and cause it to fail to open.
Uneven pressure, too, or a missing part of the valve assembly. In other words, anything that affects the sequence of events when the valve is working.
A solenoid that doesn’t open can lead to many problems. If the can lead to failure of the whole system or lost control of important functions.
As soon as the fault happens, finding out the cause can help you correct the malfunctioning part. In most cases, it can be as simple as replacing a component.
2. Solenoid Valve Not Opening or Opening Partially
This problem has several possible causes. A contaminated tube or orifice is one of them. It causes the plunger to get stuck, either at the end or halfway. Depending on the severity of the fault, the valve will fail to open or open only slightly.
Pressure differences can be another reason for the orifice failing to open or opening partially. When the pressure in a pilot operated valve is insufficient at the inlet port, the force needed to open the valve may not build to adequate levels.
Too low, and the valve may not open. Too high, and the orifice opens but not fully.
Other causes are a broken or bent valve seat, incorrect installation or a missing solenoid valve component.
Because the problem of partial or failed opening in a solenoid valve can have many possible causes, it’s advisable to rule put each one of them when finding the fault. This can help you to pinpoint the cause fast and more accurately.
3. Solenoid Valve Closing Partially
Unlike in the malfunction that causes the valve to fail to open, this problem manifests as a valve that doesn’t close fully. A partially closing valve can be the result of pressure difference, bad valve seats, or damaged solenoid tube.
It usually happens when the plunger cannot displace the seal to the required position for a total shut off.
A high pressure solenoid valve, for example, would fail to close fully if the system pressure levels are too low. This usually occurs in water or air actuated solenoid valves, that feature a pilot orifice to amplify the closing force.
A partially closed solenoid valve will also result from residual magnetism in the coil windings. When that happens, the plunger cannot move to the furthest distance, and the orifice doesn’t close tightly enough.
This problem can cause a solenoid valve to lose precision or pass media when it shouldn’t.
Both scenarios can be disastrous and call for immediate action, especially if the solenoid valve is used in a manufacturing or testing system.
Finding out the reason for the partial closure is the first step to finding the solution. In most cases, the problem can be remedied easily.
4. A Burnt Out Coil
The coil windings in a solenoid valve are prone to the effects of a short circuit, wrong voltage, and extreme temperatures. The coil may melt or burn, affecting the operation of the valve.
Apart from media temperatures and over-voltage, a solenoid valve coil will also burn due to a slow or bent armature.
This problem can be prevented by observing a few things, both during valve selection and after installation.
They include choosing a valve material that’s compatible with the type of media to be regulated, ensuring the power supply connection and circuits are in good condition, and servicing the valve regularly.
When choosing a valve to regulate hot media such as steam, it’s recommended to select a high temperature solenoid valve. These are usually made from materials that can withstand heat extremes, such as steel or brass.
5. Intermittent Valve Noise
A faulty solenoid valve may produce erratic sounds during operation. The type of noise varies depending on the exact cause and valve design.
It could be a water hammer (bang), which is common with water solenoid valves, or a continuous buzz when the coil energizes. Solenoid valve noise doesn’t have many causes, which makes diagnosis somewhat easy.
The problem can result from pressure differences across the inlet and outlet ports, or it can be due to media passing through a small pipe diameter. Valve noise can be annoying.
However, it can be corrected or even prevent from happening in the first place. When it occurs, you only need to find out the cause and apply the appropriate method to fix it.
Solenoid valves are used in many different applications, making them a common device in appliances and industrial installations.
Their failure can mean a problem in the larger system and unwanted results if the fault is not fixed on time.
Knowing the faults that mostly affect solenoid valves can help you find a malfunction before it is too late.
Then, you can take the most appropriate step to restore the function of the valve and that of the whole system.