Common faults and solutions of solenoid valve

    The rated voltage of solenoid valve coil includes DC12V, DC24V, AC24V (50 / 60Hz), AC110V (50 / 60Hz)

AC220V(50/60Hz)、AC380V(50/60Hz)。

Generally, in electrical design, either AC220V (no need to add switching power supply, low cost, simple circuit and easy maintenance) or DC24V (common safety voltage, switching power supply / solenoid valve coil are easy to repair and replace).

Method for detecting the quality of solenoid valve

    First energize the solenoid valve with the controlled medium (liquid and gas with pressure < air >, and the pressure value is the middle value of the pressure range used by the solenoid valve), and then energize the solenoid valve coil. If the controlled medium changes from on to off or from off to on, the solenoid valve is good, otherwise there is a problem.

Common faults of solenoid valve

1. Coil short circuit or open circuit

Detection method: first measure its on-off with a multimeter, and the resistance value approaches zero or infinity, which indicates that the coil is short circuited or open circuited. If the measured resistance is normal (about tens of ohms), it does not mean that the coil must be good (I once measured that the resistance of a solenoid valve coil is about 50 ohms, but the solenoid valve cannot act, and everything is normal after replacing the coil), please conduct the following final test.

Find a small screwdriver and put it near the metal rod in the solenoid valve coil, and then energize the solenoid valve. If it feels magnetic, the solenoid valve coil is good, otherwise it is bad.

Treatment method: replace the solenoid valve coil.

2. There is a problem with the plug / socket

    Fault phenomenon: if the solenoid valve has a plug / socket, there may be problems with the metal reed of the socket (the author has encountered it), the wiring on the plug (such as connecting the power line to the grounding wire) and other reasons, and the power supply cannot be sent to the coil. It's best to form a habit: screw the fixing screw after the plug is inserted into the socket, and screw the fixing nut after the valve core rod on the coil.

If the plug of solenoid valve coil is equipped with LED power indicator, it should be connected correctly when DC power is used to drive the solenoid valve, otherwise the indicator will not light up.

    In addition, do not switch the power plugs with LED power indication at different voltage levels, which will lead to the burning of LED / short circuit of power supply (replace the plug with low voltage level) or weak light emission of LED (replace the plug with high voltage level).

    If there is no power indicator, the solenoid valve coil does not need to distinguish the polarity (unlike the transistor time relay with DC coil voltage and the intermediate relay with DC coil voltage with diode / resistance leakage circuit connected in parallel on the coil < this intermediate relay is mostly from the original small Japan, and the polarity needs to be distinguished).

 &nbsp;  Treatment method: correct wiring errors, repair or replace plugs and sockets. 3. Spool problem

    Fault phenomenon 1: when the pressure of the medium connected to the solenoid valve is normal, press the red manual button of the solenoid valve, and the solenoid valve has no response (the pressure medium has no on-off change), indicating that the valve core must be broken.

    Treatment method: check whether the medium has problems, such as whether there is a lot of ponding in the compressed air (sometimes the role of oil-water separator is not great, especially when the pipeline is poorly designed, there will be a lot of ponding in the compressed air to the solenoid valve), and whether the liquid medium has a lot of impurities.

    Then remove the accumulated water or impurities in the solenoid valve and pipeline. If it doesn't work again, please repair (if you have time, patience and need it @#@) or replace the valve core, or simply replace the whole solenoid valve

 &nbsp;  Fault phenomenon 2: after inspection, the coil is the original coil, and the magnetism is normal when the coil is powered on, but the solenoid valve still does not act (at this time, the function of the manual button of the solenoid valve may be normal), indicating that the valve core is broken.

   &nbsp;Treatment: please repair or replace the valve core, or simply replace the whole solenoid valve.

    As for the maintenance of solenoid valve body, because there are too many kinds, I can't say a lot about so many maintenance methods, so I won't talk about them all here.

Troubleshooting of solenoid valve

1、the solenoid valve does not work after being energized

Check whether the power wiring is poor → rewire and connect the connector, check whether the power voltage is within ± working range - → adjust the normal position range, and whether the coil is desoldered → rewire

Coil short circuit → replace coil

Whether the working differential pressure is inappropriate → adjust the differential pressure → or replace the proportional solenoid valve, and the fluid temperature is too high → replace the proportional solenoid valve

There are impurities that make the main valve core and moving iron core of the solenoid valve stuck → clean it. If the seal is damaged, replace the seal and install the filter. The liquid viscosity is too high, the frequency is too high and the service life is up → 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

Whether the fluid temperature and viscosity are too high → replace the corresponding solenoid valve

Impurities enter the valve core or moving iron core of the solenoid valve → clean it

Spring life has expired or deformed → replace

The orifice and balance hole are blocked → clean them in time

The working frequency is too high or the service life has reached → change the product or update the product

3、Other situations

Internal leakage → check whether the seal is damaged and whether the spring is poorly assembled

External leakage → loose connection or damaged seal → tighten the screw or replace the seal

There is noise during power on → the fasteners on the head are loose and tightened. The voltage fluctuation is not within the allowable range. Adjust the voltage. Clean or replace the iron core timely in case of impurities or uneven suction surface.

Method for quickly judging the quality of solenoid valve on site

1、 First, check whether the solenoid coil of the solenoid valve is faulty?

Give the opening or closing signal to 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, there must be a problem with the coil. Is there a problem with the solenoid valve itself? (explained below)

If there is a problem with the solenoid coil, first check the wiring to see if there is a virtual connection or short circuit. If there is no problem on the circuit, the solenoid valve coil is burned out. Remove the wiring of the solenoid valve and measure it with a multimeter. If there is an open circuit, the solenoid valve coil is burned out. The reason is that the coil is damp, resulting in poor insulation and magnetic leakage, resulting in excessive current in the coil and burning. 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 coil turns are too few, and the suction force is not enough, the coil can also be burned.

2、 If the coil is good, it is the problem of the solenoid valve itself.

Generally, the valve can be adjusted from 1 to 0 in the manual adjustment position. If it can be opened, it indicates that it is indeed the problem of the coil. Just change the coil. If it cannot be opened, remove the solenoid valve to see if the valve core is stuck or blocked by impurities. CCl4 should be used for correct cleaning.

However, considering that there are no conditions on site, you can use gasoline, and there is no water. After cleaning, you can blow dry with on-site instrument air. Be sure to remember the sequence of all parts when disassembling. If you don't pay attention, it is easy to make mistakes when installing. If you remember the sequence wrong, even if you clean the solenoid valve, even if the solenoid valve has been connected, it still can't be opened!

Wenzhou Jinjiu Packaging Machinery Co., Ltd

Address: Lin Si Long Industrial Zone, Feiyun street, Rui'an City, Zhejiang Province (next to provincial highway s56)

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