Solenoid valve fault finding guide.

At some point in their life a solenoid valve will fail and stop working. The reasons for valve failure and vast and varied from dirt ingress, damage, worn out, maintenance mistakes or simply the solenoid valve is not suited to the application at hand. Some initial key pointers before you start trouble shooting here are:

• If the valve never worked - this might indicate that the valve is not suited for the application. i.e. wrong pressure, type or voltage etc, was installed incorrectly or was damaged. Check all specifications with your solenoid valve supplier.
• If the valve was working before - this might indicate that either some system changes have affected the valve, or debris has become lodged inside so some simple valve maintenance will bring the valve back online and working correctly. Check with your solenoid valve supplier before purchasing any spares.

Solenoid Valve only opens slightly

• Dirt ingress under diaphragm

Clean diaphragm / piston seals or replace if damaged. See spare parts list, maybe fit Y type strainer upstream.

• Low pressure

Check inlet/ outlet pressure difference (Differential) is in line with valve specification. If too low valve will need replacing with 0 rated version. Remember that the downstream side will rise to a higher tank or system, so should also be subtracted from the supply side pressure. Other system demands may also reduce the overall supply pressure and further reduce differentials.

• Damaged or bent armature tube

Replace tube. See spare parts available.

• Corrosion

Replace damaged components and check media compatibility with valve. Do not use EPDM seals on Oils or Fats as the seals will swell and restrict flow. Call technical help line or soak seals overnight to see if seal swells up

• Missing components after maintenance

Replace parts according to spares listing.

Solenoid Valve fails to open

• Failed power supply

Check if valve is normally closed (power to open) Or Normally Open (Power to close) Use magnetic detector lift coil slightly to check if magnetic field is present.Do not remove coil if energised as IT WILL BURN OUT Check contacts Check wire connections and DIN connector. Check fuses.

• Wrong Voltage

Check coil marked voltage is correct for supply.Check voltage tolerances normally +/- 10% however refer to solenoid-valve catalogue. Some coils work on the principle of creating an inrush condition to open the valve, check your power supply is rated for the coil current requirements. Most valves will have cable plugs rated to IP65, ensure cable gland and cable diameter are matched, plug connecting screw correctly tightened and allow cable to drop under cable gland to help prevent ingress of water droplet

• Coil burnt out

See coil burnt section

• Pressure – Too High

Check coil power rating, higher power version may be required. Reduce inlet pressure in line with valve specification as shown in solenoid-valve catalogue.

• Pressure – Too Low

Check inlet/ outlet pressure difference (Differential) is in line with design conditions of the valve. If too low valve will need replacing with 0 rated version. Remember that the downstream side will rise to a higher tank or system, so should also be subtracted from the supply side pressure. Other system demands may also reduce the overall supply pressure and further reduce differentials.

• Damaged Armature tube Replace armature tube.

See spare parts list.

• Dirt ingress in armature tube

Clean valve armature or replace. Suspended particles of dirt can be filtered out with a strainer, always mount valve with coil upright to reduce wear on the top of the solenoid armature if any dirt gets into the medium. If hard water scale builds up install water softener or dry armature valve, otherwise install Y type strainer to filter out suspended particles.

• Corrosion

Replace damaged components and check media compatibility with valve. If the armature is pitted due to Cleaning or dosing fluid? Some acids will attack the 430F stainless armature, which is corrosion resistant but not guaranteed to withstand all fluids.

• Missing components after maintenance

Replace parts according to spares listing.

Solenoid valve fails to close or partly closes

• Dirt ingress under diaphragm or piston seals.

Clean diaphragm or piston seals and remove any debris. Fit filter upstream to prevent debris entering valve.

• Residual power to coil

Lift coil slightly to check if magnetic field is present. Do not completely remove coil if energised as IT WILL BURN OUT.

• Check wiring and diagram Check lead connections.

• Dirt ingress in pilot hole under coil armature

Clean orifice with pin or compressed air.

• Manual over ride

Check position of manual over ride and adjust if required.

• Pressure pulse upstream.

Check valve technical data in solenoid valve catalogue and replace if necessary.

• Pressure difference in/out too high

Check pressure and flow Outlet pressure occasionally higher than inlet pressure Check other items in installation.

• Damaged or bent armature tube

Replace tube. See spare parts available in solenoid-valve catalogue

• Diaphragm inverted

Refit diaphragm correctly or replace with new part. See valve spares.

• Dirt ingress in armature tube

Clean valve armature or replace. If hard water scale build up install water softener or dry armature valve from solenoid valve catalogue.

• Corrosion in pilot orifice

Replace damaged components, check valve specification in suitable for application, see solenoid valve catalogue.

• Valve installed wrong way around

Check flow direction is in line with flow direction arrow or in/out markings on ports.

• Missing components after maintenance

Replace parts according to spares listing.

Water Hammer Fault Finding

• Valve Noise Appears Incorrect

Armature cannot reach top due to over pressure or debris.

Check armature tube and armature assembly for debris and clean or replace accordingly.

Check system pressure is in accordance with valve specification. Reduce system pressure.

Buzz 50 or 60Hz AC buzz. Use DC solenoid coil with DC supply or fit bridge rectified connector to convert AC supply to DC for new DC solenoid coil.

• Water hammer when valve opens

Caused by high liquid velocity and high pressure through small pipe bore.

Install a closed vertical T piece pipe in before the valve to trap an air pocket to dampen noise.

Reduce inlet pressure.

Increase pipe size to reduce velocity.

• Water hammer when valve closes

Caused by high liquid velocity and high pressure through small pipe bore. Ask supplier to reduce closing time of valve. This can be done carefully by increasing slightly (10-20%) the size of the pilot pressure equalising hole in the diaphragm. Too much and valve will not open.

Reduce inlet pressure

Increase pipe size to reduce velocity.

Install slow closing water solenoid valve.

Install anti water hammer valve.

Difference in inlet/ outlet pressure too high or pulsating pressure line. Check valve specification in solenoid-valve catalogue. Check pressure and flow. Check solenoid-valve catalogue for more suitable valve for application. Check other items in installation.

Coils & Media

• Coil Armature Slow

Replace damaged armature, see spares section in solenoid-valve catalogue.

Check media compatibility with valve.

• Bent armature tube, replace accordingly.

• Dirt in armature tube, clean and fit Y type strainer.

• Coil Burnt / Melted or Cold with Power On

Check coil marked voltage is correct with power supply. Change coil for correct one if required.

Check wiring and wiring diagram

Check voltage tolerance, normally +/- 10% consult solenoid valve catalogue.

• Coil Short Circuit

Check remaining installation for short circuit Check lead connections at coil and DIN connector

Check for moisture in coil, replace as required.

Check coil IP rating according to technical data in solenoid valve catalogue

• Media Temperature Too High

Check media temperature against valve technical data in solenoid-valve catalogue. Move valve to cooler area or increase ventilation around valve & coil. Check you have correct function normally closed or normally open.