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Valve Fails to operate

By Admin on Fri 10 February 2017 in Troubleshooting

A quick and simple guide to troubleshooting your solenoid valve.

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 electrical supply with voltmeter. Voltage must agree with nameplate rating.
  • Check coil with ohmmeter for shorted or opened coil.
  • Make sure that pressure complies with nameplate rating.
  • 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.
  • Some solenoid valves will be fitted with IP65 DIN 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.

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

  • If 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.
  • You may need to install a filter, such as our RPE filter assembly to remove debris in media.
  • Try to mount the solenoid valve with the 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 the system and carefully remove armature assembly, which will have small internal parts and replace.
  • Check media compatibility with the solenoid valve. Is the armature is pitted due to cleaning or dosing fluids? Remember acid and alkali cleaning solutions will corrode even a 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 the re-installation procedure.