The Difference Between Electric Valve and Solenoid Valve

The solenoid valve is a solenoid valve that generates a magnetic force to attract and overcome the pressure of the spring to drive the valve core to move after the solenoid coil is energized.
The electric valve drives the valve stem through the motor to drive the valve core to move, and the electric valve is divided into (shut-off valve) and regulating valve. The shut-off valve is a two-position type of work, that is, fully open and fully closed. The regulating valve is equipped with an electric valve positioner on it, and the valve is dynamically stabilized in one position through closed-loop adjustment.

Comparison of the use of electric valve and solenoid valve

Solenoid valve: used for switch control of liquid and gas pipelines, it is a two-position DO control. Generally used for the control of small pipelines.
Electric valve: It is used for analog regulation of medium flow in liquid, gas and wind system pipelines, and is controlled by AI. In the control of large valves and wind systems, electric valves can also be used for two-position switch control.
Solenoid valve: It can only be used as switch value, it is DO control, and it can only be used for small pipeline control, which is common in pipelines of DN50 and below.
Electric valve: It can have AI feedback signal and can be controlled by DO or AO, which is more common in large pipelines and dampers.

1. Switch form:

The solenoid valve is driven by a coil, which can only be opened or closed, and the action time is short when switching.
The electric valve is generally driven by a motor. It takes a certain amount of time to complete the opening or closing action, and it can be adjusted.

2. Nature of work:

Solenoid valves generally have a small flow coefficient and a small working pressure difference. For example, the flow coefficient of the general 25-caliber solenoid valve is much smaller than that of the 15-caliber electric ball valve. The driving of the solenoid valve is through the solenoid coil, which is relatively easy to be damaged by voltage shock. It is equivalent to the role of a switch, that is, on and off.
The electric valve is generally driven by a motor, which is relatively resistant to voltage shocks. The solenoid valve is quick-opening and quick-closing, and is generally used in small flow and small pressure, where the switching frequency is required to be large. The opening of the electric valve can be controlled, and the state is open, closed, half-open and half-closed, which can control the flow of the medium in the pipeline, but the solenoid valve cannot meet this requirement.
The solenoid valve can generally be reset after power off, and the electric valve needs to add a reset device for such a function.

3. Applicable technology:

The solenoid valve is suitable for some special process requirements, such as leakage, special fluid medium, etc., and the price is relatively expensive.
Electric valves are generally used for adjustment, and there are also switching quantities, such as: the end of the fan coil unit.

Common malfunctions

The solenoid valve is composed of a solenoid coil and a magnetic core, and is a valve body containing one or several holes. When the coil is energized or de-energized, the operation of the magnetic core will cause the fluid to pass through the valve body or be cut off to achieve the purpose of changing the direction of the fluid. The electromagnetic components of the solenoid valve are composed of fixed iron core, moving iron core, coil and other components; the valve body part is composed of sliding valve core, sliding valve sleeve, spring base and so on. The solenoid coil is directly mounted on the valve body, which is enclosed in a sealed tube, forming a compact and compact combination. The solenoid valves commonly used in our production include two-position three-way, two-position four-way, two-position five-way and so on. Let’s talk about the meaning of the two positions first: for the solenoid valve, it is energized and de-energized, and for the controlled valve, it is on and off.
The failure of the solenoid valve will directly affect the action of the switching valve and the regulating valve. The common failure is that the solenoid valve does not work, and should be checked from the following aspects:
1. If the solenoid valve wiring head is loose or the wire head is falling off, the solenoid valve should not be energized, and the wire head can be tightened.
2. If the solenoid valve coil is burned out, the wiring of the solenoid valve can be removed and measured with a multimeter. If the circuit is open, the solenoid valve coil will be burned out. The reason is that the coil is damp, causing poor insulation and magnetic leakage, resulting in excessive current in the coil and burning, so it is necessary to prevent rainwater from entering the solenoid valve. In addition, the spring is too hard, the reaction force is too large, the number of coil turns is too small, and the suction force is not enough, which can also cause the coil to burn out. In emergency treatment, the manual button on the coil can be turned from the "0" position during normal operation to the "1" position to make the valve open.
3. The solenoid valve is stuck: the fitting gap between the spool valve sleeve and the valve core of the solenoid valve is very small (less than 0.008mm), and it is generally assembled in one piece. When mechanical impurities are brought in or there is too little lubricating oil, it is easy to get stuck. . The treatment method can be used to poke the wire through the small hole in the head to make it spring back. The fundamental solution is to remove the solenoid valve, take out the valve core and the valve core sleeve, and clean it with CCI4, so that the valve core can move flexibly in the valve sleeve. When disassembling, pay attention to the assembly sequence of each component and the position of external wiring, so that the reassembly and wiring are correct, and also check whether the oil spray hole of the lubricator is blocked and whether the lubricating oil is sufficient.
4. Air leakage: Air leakage will cause insufficient air pressure, making it difficult to open and close the forced valve. When dealing with the failure of the solenoid valve of the switching system, an appropriate time should be selected, and the solenoid valve should be processed when the power is lost. If the processing cannot be completed within a switching gap, the switching system can be suspended and dealt with calmly.

Troubleshooting Solenoid valve does not work when energized
Different Kinds of Solenoid Valves
Different types of solenoid valves (34 photos)
Check whether the power wiring is bad → re-wire and connect the connector
Check whether the power supply voltage is within the ± working range - → adjust to the normal position range
Whether the coil is desoldered → re-soldered
Coil short circuit → replace coil
Whether the working pressure difference is inappropriate → adjust the pressure difference → or replace the commensurate solenoid valve
Fluid temperature is too high → replace the appropriate solenoid valve
Impurities make the main spool and moving iron core of the solenoid valve stuck → clean it, if the seal is damaged, replace the seal and install a oil filter
The viscosity of the liquid is too high, the frequency is too high and the life is over → replace the product
Solenoid valve does not close
The seal of the main valve core or the 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 solenoid valve core or moving iron core → clean
The spring has expired or is deformed → replace
The orifice balance hole is blocked → clean in time
The working frequency is too high or the service life has expired → re-select the product or update the product
Other situations
Internal leakage → check for damaged seals and poor assembly of springs
External leakage → loose connections or damaged seals → tighten screws or replace seals
There is noise when the power is turned on → the fasteners on the head are loose and tightened. If the voltage fluctuation is not within the allowable range, adjust the voltage. Impurities or unevenness on the suction surface of the iron core should be cleaned or replaced in time.

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