Motorized valves in automation systems

With this article, we begin a series of materials dedicated to individual elements of automation systems. In the first article, we will get acquainted with the purpose, structure and principle of operation of electromagnetic valves with electric drive.

Valves are devices that regulate: pressure, temperature, direction of flow of liquid or gas in the pipeline.

All valves can be divided into non-adjustable and adjustable, in which the geometric dimensions of the working windows or their number depend not only on the parameters of the fluid flow, but also on external influences. There are relief, pressure relief, safety, non-return and diverter valves.

Adjustable valve - a valve that changes the flow rate of a liquid (gas) that enters or is removed from the control object.

The adjustable valve is a variable hydraulic resistance with a variable flow area from zero (when the piston is seated) to a maximum (when the valve is fully open) and with a variable local resistance coefficient as the flow rate changes in magnitude and direction. Most often, the adjustable valve is connected to the actuators and usually forms a common unit with them.

Motorized valves are one of the most sought after types of pipeline equipment. With their help, you can turn off and adjust the characteristics of the flow of liquid or gas, eliminate an emergency situation. They are widely used in utilities, gas and oil industries, and agriculture.

The advantages of these devices include: high speed of opening or stopping the flow, reliability and durability in operation. The electric drive provides the possibility to work with the valves from a distance, from the control panel.

The mechanisms meet high standards for precisely regulating the temperature of hot water to supply it to the heating system. The material from which the motorized valve is made can withstand large pressure drops. Drives are manufactured with a safety function.

Pressure regulator - an electrically actuated regulating valve monitors the pressure of the working medium in the pipeline section or in the process system. Such a device consists of functionally dependent parts: drive mechanism, a distributing action on the control part, and a control valve that acts on a mass of gas or liquid.

The executive mechanism of such a system is movement powered by electricity… The main purpose of regulatory mechanisms is to control technological processes in production. The device allows continuous monitoring of the characteristics of the working environment (pressure, water or gas flow rate, temperature ...), and also prevents emergency situations, immediate inclusion of the locking equipment, protects the lines from hydraulic shocks, does not allow the reverse passage of working media.

When installing the adjusting mechanism, it is necessary to follow the direction of the water or gas mass according to the arrows shown on the body.

The pipelines on which the control valve is installed must be laid flat and securely fixed, and also protected from vibrations. The device can be installed both vertically and horizontally, but the actuator must always be on top. It is imperative to leave room for dismounting or mounting the drive.

Three-way mechanism

The three-way valve with an electric drive does not change the direction of movement of the liquid mass, its pressure is constant, only the proportions of the passage of cold and hot water change. The design of the device is such that both cold and hot liquids approach it, and a mixture of the required temperature is obtained at the outlet.

A fairly simple design of the part is a housing in which there are two inputs and one output. The adjusting element is either a rod of a certain design that can move in a vertical direction, or a ball that rotates around a fixed axis. The working element does not completely overlap the mechanism, but only directs the gas or water flows so that they mix.

The drive system, receiving commands from sensors, allows you to change the temperature of the liquid in automatic mode. The three-way part with electric drive received the most accurate adjustment, which is why it is the most widely used.

The electric drive that comes with the device can be solenoid or servo. Solenoid — this is a coil with a core through which an electric current flows, i.e. electromagnet. Servo This is a device in which an input electrical signal controls mechanical movement using a compact electric motor.

The materials from which this equipment is made include cast iron, steel and brass. Steel and cast iron devices are installed in pipelines with a large passage of water or gas. The small parts are made of brass.

Three-way devices are a popular product, because there are simply no analogues that can replace them. Only this equipment can ensure that the temperature of the working environment is maintained at the correct level. The technology for implementing three-way mechanisms is perfectly developed. The range of these products is such that the product will satisfy every demand.

A complex technical device and a significant price, but it guarantees reliability and durability during operation.

Locking mechanism

Shut-off valve with electric drive It is a shut-off valve in the form of a valve. An element that blocks the flow of water or gas moves parallel to the axis of this flow. Such devices are used to completely block the flow section. Such a locking element is a pulley that can only be in the «open» or «closed» position during the entire operation.

They also make brake adjustment equipment that has the additional function of adjusting the flow rate of the passing fluid.

Until 1982, valves of this type were called valves, but Gostas removed this name.

These devices are widely used as shut-off valves due to the reliable sealing of the spool and the simplicity of the design. They are used for gaseous and liquid media with a wide range of operating characteristics: temperatures from -200°C to +600°C; pressure from 0.7 Pa to 250 MPa.

Equipment of this type is installed on lines with a small diameter, otherwise great effort or a complex design will be required to properly install the blind in the body. A new modification of the locking device, which has a worm gear set in a housing with a cover, an electric drive, inlet and outlet flanges, a fixed sealed seat and a movable shutter.

The mechanism of the valve position indicator is a body with a removable sleeve on which an internal thread is applied. The stop of rotation and a scale on the outside indicate the position of the bolt. The gate location indicating mechanism is mounted on the worm shaft.

One revolution of the worm corresponds to the movement of the pointer by 1 mm. The result was an increase in shutter position measurement accuracy. In addition, this valve design made it possible to reduce the effort to move the valve.

If a locking mechanism is used in some area, then multi-turn electric drives are used for control.The electrically actuated shut-off valve closes and opens the pipeline system, and when the pressure in the system changes, the direction of fluid flow in the pipeline changes.

Advantages of the electrically actuated shut-off valve:

• the possibility of slowly closing or opening the pipeline, as a result of which the force of «water hammer» is reduced;
• the simple design allows to simplify the maintenance of the equipment;
• wide range of operating temperatures and pressures;
• small device sizes.

The element has high power and high operational reliability. The device belongs to energy-saving equipment, as it has the ability to switch to two power levels, which allows you to save energy.