Solenoid valves are robust and reliable and, if installed and maintained correctly, can provide many years service.
In this blog post we will look at steps that can be taken to help extend the life of your solenoid valve and keep it operating at optimal performance. We will also look at how to identify, resolve and prevent issues that may occur with solenoid valves.
Electromagnetic Proportional Directional Valve
Before installing a solenoid valve into a system consider the following points.
Check that the voltage supply matches the allowed voltage of the solenoid coil. This can be found on the label on the side of the coil.
Make sure that the pressure of the media that is to pass through the solenoid valve does not exceed the maximum pressure rating of the valve. Pilot operated solenoid valves and assisted lift solenoid valves also have a minimum pressure rating which must be met for the valve to function correctly. The pressure rating of the valve can be found on the I.D. disc located at the top of the armature tube, and is usually measured in bar.
Ensure that the media is compatible with both the construction material of the valve and the seal material.
Check that the media and ambient temperatures are within the minimum and maximum temperature rating of the solenoid valve. The effect on these temperatures caused by connected or nearby equipment should also be considered before installation.
The solenoid valve should be installed with the inlet port (usually marked as port 1) connected to the upstream flow and the outlet port (usually marked as port 2) connected to downstream. Some solenoid valves will also be marked with an arrow on the body indicating the direction the media should flow.
Ideally the solenoid valve should be installed with the armature tube pointing upwards. This should reduce the risk of any sediment in the media falling into the tube and restricting the movement of the armature.
If the media contains sediment or particles a filter should be fitted upstream of the solenoid valve to prevent contamination of the valve’s components. Impurities entering the valve may damage the internal components and cause the valve to malfunction.
Maintenance of your solenoid valve is vital to ensure that it continues to operate at an optimal level. Regular inspections of the valve’s components should be carried out to check for wear.
To inspect the valve’s components isolate the valve from voltage and fluid. Remove the top nut, I.D plate, coil and armature tube. Check for sediment, debris or corrosion inside the tube and valve body. Check that the armature/spring assembly moves freely inside the tube. Inspect the seals and o-rings for contamination or wear.
For pilot operated and assisted lift solenoid valves also remove the upper valve body and check the diaphragm for debris, tears or deformation.
It should be possible to clean away small amounts of debris as long as care is taken not to damage the components further.
Damaged or worn components should be replaced.
Solenoid coil failure can be caused by a number of factors.
Applying an incorrect voltage to the coil will cause it to fail and may cause the coil to burn out. Electrical surges or spikes may also damage the coil. Burnt out coils cannot be repaired and will need to be replaced. Always check that the electrical supply matches the voltage and frequency of the coil as shown on the coil’s label. Incorporating electrical surge protection into the system is also advised.
Contact with water or other liquids can also damage the coil and cause it to fail. If fitted with a suitable DIN connector the coil has an Ingress Protection rating of 65 but if the valve is to be situated outside or in damp conditions suitable protection should be used. Certain solenoid valves are fitted with armature tube o-rings which help to prevent water ingress between the coil and armature tube. These should be inspected regularly and if damaged or worn should be replaced.
Sediment or other particles entering the valve may cause coil failure. If the particles are allowed into the armature tube, they may restrict the movement of the armature. The coil will continue to attempt to move the armature but, because of the restriction, will eventually overheat. To prevent impurities entering the valve an upstream filter should be fitted into the system. Installing the valve with the coil and armature positioned vertically is also recommended as this reduces the risk of sediment falling into the tube.
Burnt out or damaged solenoid coils should be replaced.
Valve failure can be avoided if the valve is installed and maintained correctly and is operated within the limits of the specifications.
Identifying the root cause of a failure can be difficult as a number of factors may be involved but the following can be used as a guide.
Exceeding the pressure rating of the solenoid valve can cause damage to the valve components. Tears in the diaphragm are usually an indication of over pressure. In extreme cases excessive pressure can cause damage to the valve body and armature tube assembly. Pilot operated and assisted lift valves also have a minimum pressure rating that needs to be met for the valve to function.
Deformation of diaphragms, seals and o-rings can be caused by either the media temperature or the ambient temperature being outside the specified temperature range of the valve. Discolouration of components may also indicate that the temperature rating has been exceeded.
Sediment or particles entering the valve can affect the operation of the valve. Contamination of seals and diaphragms in this way may result in the valve not being able to close completely. If a valve is leaking it is an indication that impurities or foreign bodies are preventing the valve form sealing correctly. Contamination can also block orifices leading to valve failure.
Corrosion of the metal components of a solenoid valve or degradation of seals and diaphragm may be caused by a compatibility issue with the media and valve/seal materials. Impurities in the media can also lead to this type of failure.
● The solenoid valve is connected in the correct direction – inlet port is connected upstream and the outlet port is connected downstream, or look for an arrow on the valve body indicating the direction of flow.
● The supply voltage matches that shown on the solenoid coil (within 10%) and the coil is functioning correctly.
● If using pilot-operated valves or assisted-lift valves check that you don’t have vacuum downstream of the valve (you cannot ‘suck’ through pilot-operated solenoid valves).
● That you don’t have any back pressure (downstream pressure greater than upstream pressure).
More information on installation and maintenance of solenoid valves can be found in the instruction booklet provided with the valve.
If you require further information or advice please contact us.
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