Common faults and solutions of solenoid valves

How to deal with the malfunction of the solenoid valve

The rated voltage of the solenoid valve coil is DC12V DC24V、AC24V（50/60Hz）、AC110V（50/60Hz） 、AC220V（50/60Hz） 、AC380V（50/60Hz）。

Generally, in electrical design, either AC220V (no need to install switch power supply, low cost, simple circuit and easy maintenance) or DC24V (commonly used safe voltage, switch power supply/solenoid valve coils are easy to repair and replace) is used.

Common faults of solenoid valves include:

1. Coil short circuit or open circuit:
Detection method: First, use a multimeter to measure its continuity. If the resistance value approaches zero or infinity, it indicates that the coil is short circuited or open circuited. If the resistance value is measured to be normal (about tens of ohms), it does not necessarily mean that the coil is good. Please perform the following final test: find a small screwdriver and place it near the metal rod that is inserted into the solenoid valve coil, then power on the solenoid valve. If you feel magnetism, then the solenoid valve coil is good, otherwise it is bad.

Solution: Replace the solenoid valve coil.

2. Problem with plug/socket:

Fault phenomenon:
If the solenoid valve has a plug/socket, there may be issues with the metal spring of the socket (which I have encountered before), wiring problems on the plug (such as connecting the power cord to the grounding wire), and other reasons that prevent power from being delivered to the coil.

It is best to develop a habit: after inserting the plug into the socket, tighten the fixing screw, and after the valve core rod, tighten the fixing nut on the coil.

If the plug of the solenoid valve coil is equipped with a light-emitting diode power indicator light, it must be connected correctly when driving the solenoid valve with DC power, otherwise the indicator light will not light up. Additionally, do not indicate power sources with light-emitting diodes of different voltage levels

Swapping the power plug can cause the LED to burn out/cause a short circuit in the power supply (using a low voltage plug) or result in weak LED light (using a high voltage plug).

If there is no power indicator light, the solenoid valve coil does not need to distinguish polarity (unlike transistor time relays with DC coil voltage and intermediate relays with DC coil voltage connected in parallel with diode/resistor leakage circuits)

This type of intermediate relay is mostly original from Japan and needs to distinguish polarity.

Solution: Correct wiring errors, repair or replace plugs and sockets.

3. Valve core issue:
Fault phenomenon 1: When the pressure of the medium passing through the solenoid valve is normal, pressing the red manual button of the solenoid valve does not cause any response from the solenoid valve (the pressure medium does not change on or off), indicating that the valve core must be faulty.

Solution: Check if there is a problem with the medium, such as whether there is a large amount of compressed air inside

Excessive water accumulation (sometimes the oil-water separator is not very effective, especially when the pipeline design is poor and there is a lot of water accumulation in the compressed air passing through the solenoid valve), and whether there are many impurities in the liquid medium being passed through. Then clear the solenoid valve and pipeline

Accumulation of water or impurities. If it still doesn't work, please repair or replace the valve core, or simply replace the entire solenoid valve.

Fault phenomenon 2: After inspection, it was found that the coil is the original coil and the magnetic properties of the coil are normal when powered on, but the solenoid valve still does not operate (at this time, the manual button function of the solenoid valve may be normal), indicating that the valve core is damaged.

Solution: Please repair or replace the valve core, or simply replace the entire solenoid valve.

Electromagnetic valve malfunction and troubleshooting

1、 The solenoid valve does not work after being powered on

Check for poor power wiring - rewire and connect connectors

Check if the power supply voltage is within the working range - adjust it to the normal position range

Is the coil desoldered? - Re weld the coil. - Short circuit in the coil. - Replace the coil. Is the working pressure difference not suitable? Adjust the pressure difference T or replace the appropriate solenoid valve. If the flow temperature is too high, replace the appropriate solenoid valve

Impurities have caused the main and moving iron cores of the solenoid valve to get stuck. If there is seal damage, the seal should be replaced and a filter should be installed. The liquid viscosity is too high, the frequency is too high, and the service life has reached T. Replace the product

2、 The solenoid valve cannot be closed

The seal of the main valve core or iron moving core is damaged. Replace the seal

Is the fluid temperature and viscosity too high? Replace the corresponding solenoid valve

Impurities enter the solenoid valve core or moving iron core T for cleaning

Spring life has expired or deformed, T replacement

The balance hole of the throttle hole is blocked, and it should be cleaned in a timely manner

The working frequency is too high or the lifespan has reached T, so choose or update the product

3、 Other situations
Internal leakage: Check if the sealing components are damaged and if the spring is poorly assembled

Loose T connection or damaged seal at the leakage point, tighten the T screw or replace the seal

When powered on, there is noise. The fixed parts on the T head are loose and need to be tightened. The voltage fluctuation is not within the allowable range, adjust the voltage accordingly. If there are impurities or unevenness on the suction surface of the iron core, clean or replace it in a timely manner.

Method for quickly determining the quality of solenoid valves on site

1、 Firstly, check if there is a malfunction in the solenoid coil of the solenoid valve
Give the signal to open or close the two position valve on DCS, and then check whether the solenoid valve is powered on or off. Generally, listen to the sound on site.

If you can't hear it, then there must be a problem with the coil. As for whether there is a problem with the solenoid valve itself (explained below)
If there is a problem with the electromagnetic coil, first check the wiring to see if there is any loose connection or short circuit. If there is no problem with the wiring, it means that the electromagnetic valve coil is burnt out. Remove the wiring of the electromagnetic valve and measure it with a multimeter. If there is an open circuit, the electromagnetic valve coil is burnt out. The reason is that the coil is damp, causing poor insulation and magnetic leakage, resulting in excessive current inside the coil and burning out. Therefore, it is necessary to prevent rainwater from entering the solenoid valve. In addition, if the spring is too hard, the reaction force is too large, the number of turns in the coil is too small, and the suction force is not enough, it can also cause the coil to burn out.

2、 If the coil is good, it is a problem with the solenoid valve itself. Generally, the valve can be manually adjusted from 1 to 0 using a straight line to open it. If it can be opened, it indicates that there is indeed a problem with the coil, and a new coil can be used. If it cannot be opened, the solenoid valve should be removed to see if the valve core is stuck or if there are impurities blocking it. If cleaning is correct, CCL4 should be used. However, considering that there are no conditions on site, gasoline can be used. If there is no water, it can also be used. After cleaning, the valve can be dried with on-site instrument gas. When disassembling, it is necessary to remember the order of each component. If not careful, it is easy to make mistakes when installing, and the order can be incorrect

Even if you clean the solenoid valve correctly, even if it is already open, it still cannot be opened!