Solenoid solenoid valve: where it is used + types and principle of operation

In addition to the usual manual valves, you can also see an automatic solenoid valve in the store.It allows you not only to control the flow of liquids and gases in pipelines at a distance, but also to automate this process.

Such devices differ in internal design and purpose. However, the principle of operation for all of them is the same - the closing/opening of the tap occurs due to the operation of an electromagnet.

In this article we will look at why such a valve is needed and how it works. We will also talk about the main types of solenoid valves.

Why is a solenoid valve needed?

Solenoid valves are a category of modern shut-off valves for pipelines for a wide variety of purposes. In everyday life, such electric valves are used in cars, special equipment, water supply systems and automatic watering and heating systems.

They are also widely used in industry to regulate current and control the transport of a variety of liquids and gases.

The solenoid valve is a volatile equipment; it requires power to open or close.

The solenoid valve for water or gas does not have any sensors inside. With its help, you can only regulate or completely block the flow of the working environment. If automation of these processes is required, then you will have to additionally install external measuring instruments, tying the operation of the electrovalve to them.

For example, use an additional controller and water leakage sensorso that when a leak is detected, the solenoid valve receives the appropriate command from the controller and shuts off the pipeline.

The advantages of using solenoid valves include:

• quick adjustment of the working medium current through the pipeline;
• versatility and reliability of the device;
• long service life;
• small size and light weight;
• variety of instrument types.

The valve operates literally within a split second after the signal is given. It is designed to work with liquids under different pressures, from 0 to 25 bar, and with varying temperatures, from -20 to +120 ° C. At the same time, in a de-energized state, such an electric valve can remain either in a closed or open position - it all depends on the modification of the device.

Most often in everyday life, a solenoid solenoid valve is used in water supply and heating systems, where it is used to remotely regulate the water flow

In water supply systems, it allows you to automatically shut off the water supply if the pipes burst. And in heating systems, such a valve is used as a device for regulating the flow of coolant.

Here, using an external temperature sensor, it independently reduces or increases the flow of heated liquid from the boiler to the radiators.

How does a solenoid valve work?

The solenoid valve consists of:

• steel, cast iron, brass or polymer housings;
• induction coil with core (solenoid);
• working locking element;
• seal;
• damping spring.

The copper induction coil inside the shut-off device is located in a sealed housing, where access to water is closed.The blocking or opening of the working medium current channel occurs due to the rod and membrane extending under the action of the solenoid.

The power supply to the solenoid valve is connected via terminals on the top of the device body next to the induction coil

In a de-energized state, under the influence of a spring, the valve completely shuts off the current channel or leaves it completely open. Further, after applying voltage to the coil, the core and the rod are displaced, as a result of which the cross-section of this duct increases/decreases.

The general principle of operation of the electromagnetic valve under consideration is simple - the movement of the rod occurs in it due to electromagnetic induction. When electric current flows through the coil, the core located in its center is affected by an electromagnetic field, the strength and direction of which depend on the applied voltage in volts.

As a result, the shut-off element is displaced and the flow area of ​​the valve changes.

The solenoid valve coil, depending on the modification of the device, can operate on a voltage of 5–36 V DC or 220 V AC

Electrovalves with low control voltage are designed to operate in small diameter pipelines and with low pressure of the working medium. The scope of their application is quite limited.

But such valves are easier to integrate into a control system on low-voltage semiconductor devices and connect to various microcontrollers. They are usually used in water supply systems and heating circuits of private houses.

Types of solenoid solenoid valves

There are several varieties of the device in question.Such devices are classified according to the material of the body, design and de-energized position of the lock inside, type of seal and method of connection to the pipes.

Each of these options is designed to work with a specific medium in terms of composition, temperature and pressure. The solenoid valve must be selected carefully. If you take a device that does not meet the requirements, it will not last long.

The first and main division of solenoid valves is by type of electric current. So, they can operate on alternating or direct current

According to the method of connection, solenoid electrovalves are divided into:

• flanged;
• coupling;
• fittings.

And in size they can be from 6 to 150 DN (from 1/8 to 6 inches). There is an option for any pipeline.

The body of the electrovalves in question is made of:

• plastic (reinforced PPA, PVC, nylon);
• of stainless steel;
• brass;
• cast iron

Each of these options has its own characteristics for pressure and temperature of the working environment. These numbers should be carefully studied in the device passport so as not to make a mistake with your choice. At the same time, any of the above variations is suitable for plumbing or heating in a private house.

Classification #1 - by internal structure

Based on the design of the control element, valves are divided into three groups:

1. Spool valves.
2. Membrane.
3. Piston.

Household solenoid valves are usually made with a membrane. This is a cheap and reliable option that can easily cope with regulating the flow of water in domestic heating and water supply systems.

Internal elements - spring, plunger and core, are almost always made of stainless steel, which is highly resistant to changes in temperature and water pressure

The main separation of solenoid valves is carried out according to the position of the locking mechanism when the electromagnet is de-energized.

According to this parameter, solenoid electrovalves are divided into:

• normally closed, valve closed (NC);
• normally open, valve open (NO);
• bistable.

In the first case, until voltage is applied to the solenoid, the core is lowered down due to spring pressure and there is no water flow. In the second case, when the device is de-energized, the channel, on the contrary, is completely open, and it closes only after power is applied.

The third option is that the position can be either open or closed.

Classification #2 - based on operating principle

Functionally, solenoid electrovalves for water at 220 V and other voltages are:

• one-way;
• two-way;
• three-way.

The first ones have only one connection pipe to the pipeline. This safety devices, designed to release steam or water when the pressure in the pipes is too high.

Two-way solenoid valves are the most common and in demand. They have two pipes - inlet and outlet, and are installed in the pipeline gap

Three-way devices come with three pipe connections for connection to pipes. Such options are designed to redirect flow from one pipeline to another.

Most widely three way valves used in heating systems. Such devices make it easy to transfer coolant from one circuit to another to mix the working environment.

As a result, the temperature of the water in the system changes, but the source of thermal energy continues to operate without changing the mode.

Also, solenoid valves are:

• direct action;
• indirect action.

In the first, the core moves solely under the influence of an electromagnet. Secondly, its movement is also affected by the pressure of the working environment.

Classification #3 - based on the material of the seal and membrane

Inside the body of the solenoid valve there is a membrane that blocks the flow of water. Plus, there is a seal between the coil and the main one with the pipes. Both of these elements are made of elastic polymer materials.

Most often, in household solenoid valves for water, seals and membranes are made of EPDM, which is highly resistant to salts and low temperatures.

The seal in solenoid valves can be made of:

• FPM (FKM, VITON) – fluoroelastomer;
• EPDM – ethylene-propylene elastomer;
• NBR – nitrile butadiene rubber.

The first option is characterized by a high maximum operating temperature and resistance to oils and gasoline. The second is cheap and resistant to salts, alkalis and acids dissolved in water. The third one calmly tolerates contact with petroleum products and is usually used in industry and automobiles.

This material does not greatly affect the price of the solenoid valve. Its parts are too small in size. The type of seal and membrane should be selected based solely on the characteristics of the working environment.

The thermal properties of the seals are presented in the following table:

In any case, when operating the solenoid valve, special attention should be paid to the absence of impurities in the water.

Sand and rust in pipes will sooner or later ruin any membrane, regardless of its material. The device in question can only be installed if there is a filter in the pipeline.

Conclusions and useful video on the topic

Solenoid valve device overview:

How a 220 V direct acting solenoid valve works and works:

Types of solenoid valves according to the operating principle:

The remote control solenoid valve is unpretentious and reliable in operation. It is designed for several tens of thousands of operations (it will work properly for 20–25 years) and does not require specialized maintenance.

Such a device for water costs between 3-6 thousand rubles, but it helps solve many problems. At the same time, it is not difficult to install it yourself; you just need to choose the right valve according to the characteristics and materials.

Would you like to add useful information to the above material or point out an inconsistency or error? Or would you like to give recommendations on choosing the optimal model of solenoid valve? Please write your tips and comments in the comments block.

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