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. 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.
These are usually made from materials that can withstand heat extremes, such as steel or brass. 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.
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. Check for compatibility between the fluid and the material of the valve before installation and startup.
In case of doubt, please contact the manufacturer. Always connect the coils earth terminal to ground. Do not use the tubes for the transport of fluids to ground electrical devices.
Valve must be supported only by the provided connections, where unforseen. Tubes must not transmit static load or vibrations to the valve. Do not use the valve as a support for other equipment or fittings.
The fixing holes, where provided, or anything else on the valve body must not be modified. Whilst tightening or unscrewing the valve must be held or revolved only and exclusively by the hexagon on the frameset.
The use of other components such as a coil, armature or cover could cause irreparable damage to the valve. Care should be taken to prevent foreign bodies — dirt or material chips — from entering the valve during the assembly phase.
In those installations where impurities or deposit of various type may infiltrate the fluid, the installation of a suitable filter is recommended.
Use suitable seal material on the valve threads. In the installations where liquid cement is used, it is important to prevent them from entering the valve and block the movement. Do not shut the holes of pilot operated solenoid valve circuit. The coil should not be energised before being installed on the valve or without the armature assembly inside since this could cause it to burn out or break.
The valve can operate in any position. The vertical installation with upside coil is highly recommended to avoid any impurity fall into the obturator and to extend the life of the valve. The coil temperature normally increase during operation this is a normal condition. Irregular overheating will cause smoke and smell of burning. In this case the power supply must be immediately stopped. Install the valve far from sources of heat and in environments where the heat produced by the coil can be easily dissipated.
It is important to respect the flow direction, the pressure and the technical data on the label. Refer to figure 1 Direct acting solenoid valve and figure 2 Pilot operated solenoid valve to disassemble the internal components of the valve.
Clean the internal parts disassembling the valve figure 1 and 2 ; Remove dirt and dust and then reassemble all the components. When purchasing spare parts, ALWAYS mention the model and the code of the valve indicate on the valve plate and the date code mentioned on the coil label. Conduction of heat through the oil surrounding the winding allows the coil to operate at a lower temperature.
In plants where instrumentation is available, a thermocouple can be placed on the surface of the winding in two identical valves of the type to be used. One valve can be continuously cycled for several hours at the proposed cycle rate while the other is continuously energized.
A difference of more than a few degrees in surface temperature of the two coils indicates a need for oil immersed solenoids. High Electrical Transients If the current for the solenoid valves is taken directly from a power line which is supplying large inductive devices such as electric motors, the switching of these motors may cause high voltage transients which may break down the insulation of solenoid valve coils. A 'thyrector" should be installed across each coil to "short circuit" these transients.
Thyrectors are available at industrial electrical supply houses. Dirt in Oil or in Atmosphere A small solid particle lodging under the solenoid armature may keep it from fully seating against the core, causing coil current to remain higher than normal during the holding period.
Be sure that solenoid dust covers remain tightly in place to protect against dust deposited from the air. Small dirt particles in the oil may lodge on the surface of the spool, glued there by "varnish" circulating in the oil, or the varnish itself may cause excessive spool drag and excessive coil current.
Heat accelerates unwanted chemical reactions. Reduce oil temperature with a heat exchanger. Environmental Conditions Abnormally high or abnormally low ambient temperatures to which a solenoid is exposed for an extended time may cause a solenoid to burn out. Dead End Service Fluid circulating through a solenoid valve helps to carry away electrical heat. Some valves depend on fluid flow to keep excessive heat from accumulating, and if used on dead end service, where the solenoid remains energized for long periods without fluid flow, the coil may burn out from this effect, possibly in combination with other problems.
Atmospheric Moisture High humidity, coupled with frequently changing ambient temperature, may form corrosion on metal parts of the solenoid structure, causing the armature to drag or the spool to stick. Humidity also tends to deteriorate standard solenoid coils, causing shorts in the winding. Change to molded coils or oil immersed solenoids. Keep solenoid protective covers tightly in place, and perhaps seal the electrical conduit openings after the wiring is installed.
If you find the pressure to be too low for the valve, consider replacing it with one whose pressure requirement matches that of the system. Clean the affected part to remove the dirt causing the component to jam. In case of damage, such as torn diaphragm for pilot solenoid valves, replace the affected part. Install a missing component. This problem can result from inadequate pressure, damaged components such as the armature and tube, dirt on the diaphragm, valve seat, or tube, corrosion, and missing parts.
Solutions depend on the affected part or the type of fault. An indirectly operated or pilot solenoid valve will not open fully if certain pressures levels are not attained. If the diaphragm, seat valve or tube are dirty, clean them. Replaced broken or damaged components. Corroded parts may not function as required and should be replaced. Install missing components, too. Among the causes of this solenoid valve problem are coil issues, dirt or damage in the moving parts such as membrane or tube, pressure differential or pulsating pressure , damaged armature and valve seal, missing parts, or simply wrong installation.
You may need to check the connections or replace the coil. Check the valve pressure specifications against those of the source or medium. Re-install components that you find to have been placed incorrectly and replace the missing ones. Water hammer or thumping sounds may indicate pressure differences in the ports.
It could also be that the flow of the medium is pulsating. Buzzing sound is often a normal occurrence when alternating current flows in the coil windings. In some instances, the surrounding parts of the valve pick up the noise and cause it to amplify. Reduce the media speed by increasing the diameter of the piping.
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