Finding: Burnt-out coil

Cause: Incorrect voltage/frequency. (Coil cold with voltage on) Check coil data.

Action: Replace with correct coil if necessary. Check wiring diagram or wiring itself. Check max. voltage variation. - Permissible variation: 10% higher than rated voltage 15% lower than rated voltage.

Cause: Armature will not lift in armature tube. a) Damaged or bent armature tube b) Damaged armature c) Impurities in armature tube (Coil cold with voltage on)

Action: Replace defective components. Clean out impurities. Replace O-rings and gaskets.

Cause: Short-circuit in coil (can be moisture in coil).(Coil cold with voltage on)

Action: Check remainder of system for short-circuiting. Check lead connections at coil. After remedying fault, re- place coil (make sure voltage is correct). Check O-rings fitted on armature tube. Ensure that coil is clicked firmly home.

Cause: Temperature of medium too high.(Coil cold with voltage on)

Action: Check remainder of system for short-circuiting. Check lead connections at coil. After remedying fault, re- place coil (make sure voltage is correct). Check O-rings fitted on armature tube. Ensure that coil is clicked firmly home.

Cause: Ambient temperature too high.(Coil cold with voltage on)

Action: Change of valve position might be necessary. Compare valve and coil data with installation data. Increase ventilation around valve and coil.

Cause: Damaged piston, piston rings (on servo-operated solenoid valves type EVRA). (Coil cold with voltage on)

Action: Replace defective parts. Replace O-rings and gaskets.

Finding: Solenoid valve opens partially

Cause: Continuous voltage on coil

Action: "Check whether the coil is energized: Use a magnetic field detector Lift coil and feel whether there is any resistance. PLEASE NOTE! - Never take the coil off the valve if voltage is applied! The coil may burn out.

Action: Check the wiring diagram and wiring itself. - Check relay contacts. - Check power connections. - Check fuses."

Cause: Pulsation in discharge line. Differential pressure too high in open position.

Action: Check technical data of valve. Check pressure and flow condition.

Cause: Damaged or bent armature tube.

Action: Replace with suitable valve. Check remainder of system.

Cause: Diaphragm or support plate wrong way round.

Action: Check for correct valve assembly Replace O-rings and gaskets.

Cause: Corrosion/cavitation of pilot/main orifice.

Action: Replace defective parts Replace O-rings and gaskets.

Cause: Manual spindle not screwed back after use

Action: Check spindle position.

Cause: Pressure in outlet side sometimes higher than in Check technical data of valve.

Action: Check pressure and flow condition inlet. Replace with suitable valve. Check remainder of system.

Cause: Defective valve plate, diaphragm or valve seat.

Action: Check pressure and flow conditions. Replace defective components Replace O-rings and gaskets.

Cause: Impurities in valve plate. Impurities in pilot orifice. Impurities in armature tube.

Action: Clean out impurities. Replace O-rings and gaskets.

Cause: Missing components after dismantling of valve.

Action: Replace missing components Replace O-rings and gaskets.

Finding: Solenoid valve does not close/ closes partially

Cause: No voltage at coil

Action: Check whether the valve is open or closed: 1) Use a magnetic field detector 2) Lift the coil and feel whether there is resistance. PLEASE NOTE! - Never take the coil off the valve if voltage is applied! The coil may burn out. - Check the wiring diagram and wiring itself. - Check relay contacts. - Check power connections. - Check fuses.

Cause: Burnt-out coil

Action: See symptom "Burnt-out coil"

Cause: Differential pressure too low

Action: Check technical data and differential pressure of valve. Replace with suitable valve. Check diaphragm and/or piston rings and replace O-rings and gaskets Replace O-rings and gaskets

Cause: Incorrect voltage/frequency.

Action: Compare coil data with installation data. Measure operating voltage at the coil. - Permissible variation: 10% higher than rated voltage. 15% lower than rated voltage. Replace with correct coil if necessary.

Cause: Differential pressure too high

Action: Check technical data and differential pressure of valve. Replace with suitable valve. Reduce differential. pressure e.g. inlet pressure.

Cause: Damaged or bent armature tube

Action: Replace defective components Replace O-rings and gaskets

Cause: Impurities in diaphragm/piston

Action: Replace defective components Replace O-rings and gaskets

Cause: Impurities in valve seat. Impurities in armature/ armature tube.

Action: Replace defective components Replace O-rings and gaskets

Cause: Corrosion/cavitation.

Action: Replace defective parts Replace O-rings and gaskets.

Cause: Missing components after dismantling valve.

Action: Fit missing components. Replace O-rings and gaskets.

Finding: Solenoid valve does not open

Cause: Differential pressure too low.

Action: Check valve technical data and differential pressure. Replace with suitable valve. Check diaphragm and/or piston rings and replace O-rings and gaskets.

Cause: Damaged or bent armature tube.

Action: Replace defective components. Replace O-rings and gaskets.

Cause: Impurities in diaphragm/piston.

Action: Clean out impurities. Replace defective components. Replace O-rings and gaskets.

Cause: Corrosion/cavitation.

Action: Replace defective parts Replace O-rings and gaskets.

Cause: Impurities in valve seat. Impurities in armature/armature tube.

Action: Clean out impurities. Replace defective parts. Replace O-rings and gaskets.

Cause: Missing components after dismantling valve.

Action: Fit missing components. Replace O-rings and gaskets.

Finding: Solenoid valve noisy

Cause: Frequency noise (hum).

Action: The solenoid valve is not the cause. Check electrical supply.

Action: O-ring on armature under coil missing. Remount the O-ring. Do not remove coil when energized.

Cause: Liquid hammer when solenoid valve opens.

Action: Try smaller size and position solenoid valve closer to expansion valve.

Cause: Liquid hammer when solenoid valve closes.

Action: System design problem - try to position solenoid valve after a pipe bend. If possible use solenoid valve with smooth closing feature.

Cause: Differential pressure too high and/or pulsation in discharge line.

Action: Check technical data of valve. Check pressure and flow conditions. Replace with suitable valve. Check remainder of system.