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Solenoid Valve Fault Finding Chart

Posted on 11/12/2016 9:47:17 AM

Solenoid Valve Fail Guide.

If your solenoid valve stops working, fails, over heats, buzzes, fails to close or fails to open, never worked, worked for a while or just died after years of use then this guide may prove helpful.

Solenoid valves are designed to control, divert or simply open and close against liquid, gas or even vacuum media. A solenoid valve utilises an electromagnetic or electrically generated magnetic field via the solenoid coil to move or lift an internal stainless steel armature assembly. This assembly will either open an internal pilot circuit or be directly linked to a main piston or diaphragm to change the state of the main valve to open, close or divert media.

Problems will occur due to overheating, debris ingress, general wear and tear to moving parts or seals over time and engineers can feel left in the dark knowing what the problem is, which part needs replacing or simply how or why the solenoid valve has failed.Today the diesel injection parts and common rail parts suppliers  - China Balin Power Co.,Ltd will provide a simplified fault diagnosis chart which will guild you to find the probable reason for the failure of your solenoid valve.

Solenoid Valve does not open

 Possible Cause of Failure

Failed Power Supply

Check that your solenoid valve is fail-safe closed (Normally Closed) or fail-safe Open (Normally Open)

Use Magnetic detector next to coil or touch with insulated metal screwdriver to detect any magnetic field.

Slightly lift solenoid coil to detect any magnetic resistance but do not remove coil when energised as coil will quickly over heat and burn out.

Check electrical contacts and electrical DIN connector.

Check fuses.

Wrong Voltage Applied

Check the coil voltage label is correct for the voltage being supplied.

Check voltage tolerance typically +/- 10% or 15% is in line with actual voltage supplied.

Most Ac alternating current solenoid coils utilise a higher inrush current (VA) to move the valve before dropping down to a holding current. Check that your supply current (AMPS) is sufficient for the inrush current rating for the coil.

Most solenoid valves will be fitted with IP65 DIN43650 electrical connectors, make sure the cable gland is securely fastened to the cable and not loose, check the DIn plug to coil connecting screw is correctly tightened about 2 Nm and allows the cable to drop below under the cable gland entry preventing any water droplets gravitating into the connector.

Burnt or Cooked Coil Check the Coil Burnt Section.
Pressure - Too High

Check coil power rating usually 10 or 15 watts, some solenoid valves are available with higher power 18 to 20 watt coils for high pressure applications.

reduce the inlet pressure back down to or below the maximum pressure rating of the solenoid valve. We do stock pressure reducing valves too if this helps.

Pressure - Too Low

Check inlet and outlet pressure differential (difference) are correct for the solenoid valve being used. Pressure assisted, pilot or servo assisted solenoid valves must have at least 0.3 to 1 bar pressure difference to operate. If the pressure difference between the inlet and outlet pressure is too low replace valve with a zero rated or assisted lift direct acting type or reduce the back pressure to the valve to achieve the required pressure differential. Keep in mind reducing bushes, control valves, pipe bends and vertical pipes all generate back pressures.

Damaged solenoid valve armature

The armature tube (the bit the solenoid coil fits onto) is damaged, isolate the valve remove the power supply, drain the system and replace the core tube. Ask your engineer to be more careful in future or fit a well vented protection cover.

Dirt Ingress under diaphragm or seal.

Isolate the solenoid valve, remove power supply, drain system and carefully remove solenoid valve diaphragm avoid loosing small parts or internal springs, remember seal position take a photo so new seal is installed correctly.

Dirt Ingress in solenoid valve armature tube

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts. Clean armature assembly or replace. Install Y pattern filter, such as our YSS filter assembly to remove debris in media, try to mount solenoid valve with armature vertical so any small particle debris will tend to gravitate down and flush out. If the armature assembly has lime scale build-up due to hard water it is advised to install a water softener into the system to prevent lime scale in all systems.

Corrosion

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts and replace. Check media compatibility with the solenoid valve. If the armature is pitted due to cleaning or dosing fluids? Remember acid and alkali cleaning solutions will corrode the 430F stainless steel armature and care must be taken to dilute any cleaning chemicals BEFORE being used. Pouring concentrated cleaning chemicals into any system and then trying to mix with water afterwards will not correctly dilute all of the chemical which will become trapped and cause severe corrosion in armature assemblies and other dead end circuits. 

Lost components during maintenance

Replace components according to manufacturers spares listing. Try to remove any parts carefully and it is helpful to use your phone camera as a reference for he re installation procedure.

Solenoid Valve only opens slightly

 

Low Pressure

Check inlet and outlet pressure differential (difference) are correct for the solenoid valve being used. Pressure assisted, pilot or servo assisted solenoid valves must have at least 0.3 to 1 bar pressure difference to operate. If the pressure difference between the inlet and outlet pressure is too low replace valve with a zero rated or assisted lift direct acting type or reduce the back pressure to the valve to achieve the required pressure differential. Keep in mind reducing bushes, control valves, pipe bends and vertical pipes all generate back pressures.

Bent or disfigured armature tube

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts and replace. Install a well ventilated guard to protect the solenoid valve.

Dirt Ingress under diaphragm or seal.

Isolate the solenoid valve, remove power supply, drain system and carefully remove solenoid valve diaphragm avoid loosing small parts or internal springs, remember seal position take a photo so new seal is installed correctly.

Corrosion

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts and replace. Check media compatibility with the solenoid valve. If the armature is pitted due to cleaning or dosing fluids? Remember acid and alkali cleaning solutions will corrode the 430F stainless steel armature and care must be taken to dilute any cleaning chemicals BEFORE being used. Pouring concentrated cleaning chemicals into any system and then trying to mix with water afterwards will not correctly dilute all of the chemical which will become trapped and cause severe corrosion in armature assemblies and other dead end circuits.

Lost components during maintenance

Replace components according to manufacturers spares listing. Try to remove any parts carefully and it is helpful to use your phone camera as a reference for he re installation procedure.

Solenoid Valve fails to close correctly or partially closes

 
Residual electrical power to coil

Lift the solenoid coil slightly (do not remove completely as coil will burn out quickly) to feel if there is residual magnetic field.

Check wiring

Check lead connections

Remove electrical DIN connector from coil to isolate coil.

Dirt Ingress under diaphragm or seal.

Isolate the solenoid valve, remove power supply, drain system and carefully remove solenoid valve diaphragm avoid loosing small parts or internal springs, remember seal position take a photo so new seal is installed correctly.

Manual Over Ride Facility

Check the position of the manual over ride and adjust accordingly.

Upstream pressure pulse

Check inlet and outlet pressure differential and flow are correct for the solenoid valve being used.

Check other valves downstream in the system are not generating excess back pressure.

Pressure difference inlet/outlet too high

Reduce inlet pressure install pressure reducing valve, we do stock these.

Install correct solenoid valve to meet the system pressure requirements.

Outlet pressure sometimes higher than inlet pressure

Install non return valve downstream of solenoid valve to prevent back flow, we do stock these.

Check pressure control valves in system are correctly set up.

Install bi-directional solenoid valve, coaxial valve or angle seat piston valve that are designed to control flow in both directions.

Bent or disfigured armature tube

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts and replace. Install a well ventilated guard to protect the solenoid valve.

Damaged diaphragm base or valve seat

Replace solenoid valve.

Check solenoid valve is in accordance with system requirements.

Inverted diaphragm

Isolate the solenoid valve, remove power supply, drain system and carefully remove solenoid valve diaphragm avoid loosing small parts or internal springs and install new seal correctly.

Dirt Ingress in solenoid valve armature tube

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts. Clean armature assembly or replace. Install Y pattern filter, such as our YSS filter assembly to remove debris in media, try to mount solenoid valve with armature vertical so any small particle debris will tend to gravitate down and flush out. If the armature assembly has lime scale build-up due to hard water it is advised to install a water softener into the system to prevent lime scale in all systems.

Corrosion in pilot orifice

Isolate electrical supply drain system and replace damaged components.

Check solenoid valve specification is suitable for the application.

Solenoid valve installed wrong way around

Check that the solenoid valve flow direction in in line with the system flow requirements, typically solenoid valve is marked inlet and outlet, flow arrow or port 1 (IN) and port 2 (OUT). Pressure assisted solenoid valves will have coil mounted over outlet. View internal thread of valve as outlet is typically deeper / longer than inlet side.

Lost components during maintenance

Replace components according to manufacturers spares listing. Try to remove any parts carefully and it is helpful to use your phone camera as a reference for he re installation procedure.

Solenoid Valve noise appears audibly incorrect

 
Solenoid valve buzz

A solenoid buzz at 50Hz or 60Hz is a sign that an AC (alternating current) is being applied to the solenoid valve and the armature is either restricted, without a copper shading ring or a wrong AC voltage has been applied.

Install a DC (Direct current) solenoid valve coil and supply a DC voltage. Engineers can install a DC coil with a bridge rectified DIN43650 electrical connector that will convert the incoming AC voltage to DC. WE stock DIN2R rectified DIN electrical connectors.

Water hammer/ pipe bang when solenoid valve opens

Caused by high water or liquid velocity (speed) typically a high pressure through a small bore.

Install an anti water hammer device, which we stock or install a vertical blanked ended pipe with air pocket to absorb water pressure shock waves.

Reduce inlet pressure.

Increase pipe size to reduce velocity (speed) of ravelling media.

Water hammer / pipe bang when solenoid valve closes.

Caused by high velocity (speed) liquid media and high pressure through small pipe or valve bore.

Ask supplier to reduce closing time of solenoid valve. This is achievable by carefully increasing the pilot hole in the diaphragm by 10-20% but this hole must remain smaller than the centre hole otherwise the solenoid valve will not close.

Reduce inlet pressure.

Increase pipe size to reduce or slow down media velocity (speed).

Differential pressure too high or pulsating pressures in line.

Check solenoid valve specification meets the requirements of the system. Pressure assisted or servo assisted solenoid valves require a stable minimum pressure difference between inlet and outlet. If a pressure assisted valve is over sized or incorrectly specified when the valve opens the downstream back pressure will cause the valve to momentarily close until the back pressure drops and then the solenoid valve will open again and the cycle will repeat.

Check other valves in the installation.

Coil Burnt, cooked, melted or cold when power is on.

 
Wrong voltage applied

Check coil marked voltage is correct for the voltage being supplied.

Change the solenoid coil for the correct one.

Check wiring and wiring diagram.

Check voltage tolerance, typically +/- 10% or 15%.

Coil short circuit

Check remaining installation for short circuit.

Check electrical connections at coil and DIN connector.

Check moisture in coil, replace as required. Check IP ingress protection is in accordance to requirements.

Coil armature slow

Isolate electrical supply drain system and carefully remove armature assembly, which will have small internal parts and replace. Install a well ventilated guard to protect the solenoid valve armature.

Direct in armature tube, clean and install Y pattern YSS in-line filter, which we stock. Install solenoid valve with armature vertical so particle debris will gravitate downwards and flush out of the solenoid valve.

Media temperature too high

Check media temperature is correct for the solenoid valve specification.

Move solenoid valve away from the heat source into a cooler area or increase ventilation.

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