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Solenoid Valve Trouble Shooting Guide and Frequently Asked Questions.

Solenoid valves aredesigned for the ON/OFF control 2/2 way or diverting control 3/2 way of liquidor gas media along a pipeline and at some point in its life will break down andfail to work. The trouble shooting guide below gives a probable explanation andsolution as to why your solenoid valve has stopped working.

Keep in mind that is asolenoid valve has broken down and stop working after a short period of timethere is obviously something about the application that the installed solenoidvalve is not suited too. Adversely if your solenoid valve has been working foryears it might well be a service or maintenance period is probably overdue.>Over the years we have seen a few of our solenoid valves returned because of apparent RUST problems, but in fact it is not the solenoid valve that is rusting its the rust or metal particles in the water media being controlled. However the same cannot be said for other solenoid valves available on the market today.
Solenoid valve fails to open
Probable Causes
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
Check 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 in solenoid-valves.com    catalogue
Dirt ingress under diaphragm
Clean diaphragm or replace if damaged. See spare parts list in solenoid-valve catalogue, maybe fit Y type strainer upstream to filter out suspended particles.
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 from solenoid-valve catalogue, 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 as per solenoid-valve catalogue
Solenoid valve opens slightly
Probable Cause
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 in solenoid-valve catalogue
Dirt ingress under diaphragm
Clean diaphragm or replace if damaged. See spare parts list in solenoid-valve catalogue, maybe fit Y type strainer upstream.
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 it swells up.
Missing components after maintenance
Replace parts according to spares listing as per solenoid-valve catalogue.
Solenoid valve fails to close or partly closes
Probable Cause
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 in solenoid-valve catalogue.
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 as per solenoid-valve catalogue.
Valve Noise Appears Incorrect
Probable Cause.
Buzz
50 or 60Hz AC buzz. Use DC valve with rectified connector. See connector’s section in solenoid-valve catalogue.
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.
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.
Coil Burnt / Melted or Cold with Power On
Probable Cause
Wrong Voltage
Check coil marked voltage is correct with power supply.
Change coil for correct one if required. See coils section in solenoid-valves catalogue.
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 IP rating according to technical data in solenoid-valve catalogue
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.
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

How do I prove my solenoid valve is or is not rusting?

The proof is easy to obtain, simply wipe away the brown rust and expose the metal surface beneath. If the valve components are rusting there will be visible pitting and corrosion however if the surface can be wiped clean and is shiny without any pitting then the solenoid valve is not rusting, the rust has arrived there from upstream. 

Where is the rust in my solenoid valve coming from?
If the valve shows no signs of rusting or corrosion then by pure logical deduction the rust has arrived from upstream equipment or mains water supply. Remember a solenoid valve utilises a magnetic field to operate and any metal or rust impurities in the media will be magnetically attracted to the valve parts. It is most likely that some other valve, pipework or equipment is generating the rust which in turn travels downstream until trapped by a filter or magnetic field. In many cases the mains water supply itself will contain rust particles from old pipelines or slightly contaminated water systems. 
Solution: install a filtration system, use a non magnetic control valve such as an actuated ball valve with failsafe close or try installing a solenoid valve that requires shorter power on time (I,e, if powered open all day, try using a normally open valve instead to power close).

Solenoid valve sulphurdisation problems.

Recently we found rust on the solenoid valve tube. But the funny thing is we did not find any rust before. Can different batches of this stainless steel give different properties? If yes, what can we do to check it?

 

This is quite typical for 303 stainless steel tubes, that are constructed from a high sulphur free machining grade stainless. You may be having a sulphide problem and not a rusting problem at all. Sulphides will bloom to the surface when exposed to moisture and look very similar to rust. Try soaking the part in 10% NaOH (Sodium Hydroxide) overnight and see if it goes away. If it does go away or wipes off it is sulphides, not rust.  


Water Hardness the affects on Solenoid Valves. 
Hard water under a threshold of 20-25 French degrees the valve should not be affected by scale build ups provided that the system undergoes regular servicing.
Nickel plated bodies and covers offer a better response.
If you are aware of possible scale build ups then you should have equipped the plant with a  water softening system, since water treatment is the only solution to be recommended and will prevent limescale build up in all other systems.
 
French degrees (°f) (shares symbol with degree Fahrenheit, but in lowercase) - conversion to mg/L calcium: divide by 0.25
One degree French corresponds to one part calcium carbonate in 100,000 parts of water.

 
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