Solenoid Valves - Faults and Their Solutions

Probable Cause

Remedy

No voltage on the coil

Check whether the valve is open or closed without power (NO or NC): 
1. Use a magnetic detector
2. Slightly lift the coil to see if it offers resistance – the coil must not be removed under voltage, otherwise it could burn out.
Check relay contacts. Check wire connections. Check fuses.

Incorrect voltage/frequency

Check that the electrical requirements for the coil match the installation supply voltage. Measure the voltage on the coil.
Allowed voltage deviations:
+/- 10% for dual frequency;

applications with direct current and NO + 10% / - 15% for alternating current, single frequency voltage. If necessary, replace the coil with the correct version.

Too high differential pressure

Check coil data. If necessary, replace the coil with the correct version. Reduce differential pressure, for example by reducing the inlet pressure.

Too low differential pressure

Check coil data, including differential pressure. If necessary, replace the coil with the correct version.

Damaged or bent armature tube

Replace the valve.

Debris on the diaphragm

Clean the diaphragm. If necessary, replace faulty components.

Debris in the valve seat, armature, or armature tube

Clean the valve. If necessary, replace faulty components.

Corrosion

Replace faulty components.

Missing components after valve disassembly

Supply missing components.

Probable Cause

Remedy

Too low differential pressure

Check valve data, including differential pressure. Replace the valve with the correct version.

Damaged or bent armature tube

Replace the valve.

Debris on the diaphragm

Clean the diaphragm. If necessary, replace faulty components.

Debris in the valve seat, armature, or armature tube

Clean the valve. If necessary, replace faulty components.

Corrosion

Replace faulty components.

Missing components after valve disassembly

Supply missing components.

Probable Cause

Remedy

Humming

Humming caused by AC frequency. Can be eliminated by replacing with a coil with a rectifier

Hydraulic shocks when opening the valve / Hydraulic shocks when closing the valve

Hydraulic shock is a typical result of high fluid velocity.            This problem has several solutions:
1. Reduce pressure by installing a pressure reducing valve before the solenoid valve. If possible, increase the pipe diameter.
2. Limit hydraulic shock by installing a flexible hose or flexible buffer  before the solenoid valve

Differential pressure is too high / pulsation in the pressure pipe

Check valve data, incl. differential pressure. Check fluid pressure and flow. Replace the valve with a more suitable type of valve. Check other installation components.

Probable Cause

Remedy

Voltage remains on the coil

First, slightly lift the coil to see if it offers resistance. Note: The coil must not be removed under voltage, otherwise it could burn out. Check wire connections according to the wiring diagram. Check relay contacts. Check wire connections.

Debris in the pilot hole / balancing nozzle

Clean the hole with a needle or similar object (max. diameter 0.5 mm). Blow the hole with compressed air. If necessary, replace faulty components.

Manual opening unit cannot be screwed back after use

Check the position of the opening unit and adjust it as needed.

Pulsation in the pressure pipe. Differential pressure is too high in the open position. The pressure on the outlet side is periodically higher than the pressure on the inlet side.

Check valve data. Check fluid pressure and flow. Replace the valve with a more suitable type of valve. Check other installation components.

Damaged or bent armature tube.

Replace the valve.

Faulty valve spring cup, diaphragm, or valve seat.

Check fluid pressure and flow. Replace faulty components.

Diaphragm in reverse position

Check correct valve installation.

Debris in the valve seat or armature tube

Clean the valve. If necessary, replace faulty components.

Corrosion in the pilot / main hole

Replace faulty components.

Valve mounted incorrectly

Check the direction of fluid flow and ensure the arrow points in the same direction.

Missing components after valve disassembly

Supply missing components

Probable Cause

Remedy

Incorrect voltage / frequency

Check coil data. If necessary, replace the coil with the correct type. Check wire connections according to the wiring diagram. Check maximum voltage deviations.                    Allowed voltage deviations:  +/- 10% for dual frequency, direct current applications
+ 10% or - 15% for alternating current, single frequency voltage

Coil shorted (moisture may be present in the coil)

Check other installation components for possible short circuits. Check wire connections to the coil. After finding the fault, replace the coil. Consider whether it would be appropriate to install a snap-on coil with an additional sealing O-ring (only for high-performance valve series).

Prolonged flow through the armature      1) Damaged or bent armature tube
2) Damaged armature
3) Debris in the armature tube

Replace faulty components. Remove debris.

Too high medium temperature

Check valve and coil data to ensure they match installation parameters. Replace with a suitable type of coil or valve.

Too high ambient temperature

If possible, move the valve to a cooler environment. Check valve and coil data to ensure they match installation parameters. Improve ventilation around the valve and coil.