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
- Low pressure
- Damaged or bent armature tube
- Corrosion
- Missing components after maintenance
Solenoid Valve fails to open
- Failed power supply
- Wrong Voltage
- Coil burnt out
- 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.
- Dirt ingress in armature tube
- Corrosion
- Missing components after maintenance
Solenoid valve fails to close or partly closes
- Dirt ingress under diaphragm or piston seals.
- Residual power to coil
- Check wiring and diagram Check lead connections.
- Dirt ingress in pilot hole under coil armature
- Manual over ride
- Pressure pulse upstream.
Check valve technical data in solenoid valve catalogue and replace if necessary.
- Pressure difference in/out too high
- Damaged or bent armature tube
- Diaphragm inverted
- Dirt ingress in armature tube
- Corrosion in pilot orifice
- Valve installed wrong way around
- 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.
Install slow closing, anti water hammer solenoid valve
Install motor actuated ball valve.
- 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.
Install motor actuated ball 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.
According to the laws of physics current can only flow in a closed circuit, if this is interrupted that current can no longer flow. So a burnt coil is open circuit - no current.
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.