Solenoid electro valves vs. motor-driven electro valves.

Electric valves play an important role in a myriad of projects and I wonder if they need to be driven by solenoids or motors. If you've ever found this question, you'll be lucky, and in this post I will explain when to choose one. First, let's summarize what a solenoid valve is and what type exists.

An electric valve is an electromechanical valve designed to control the flow of gas or fluid through a tube or pipe. They usually have two positions: open and closed. But like everything in life, whether black and white or not, it's not always the right answer. That is why today's proportional electric valves are so popular that they allow infinite intermediate configurations.

The electric valves are specially designed for use with water, oil, gas, air, fuel or steam and can be two to five directional valves. It can also be made of tin, stainless steel or PVC, depending on the fluid used.

In general, it works in three ways, depending on the intended use.

Direct acting: The electric command directly drives the opening and closing of the valve through the piston.

Indirect acting: Upon receiving the electric command, the piston can be activated, which can open or close the main diaphragm in auxiliary (or indirect) operation. This type of valve requires a minimum pressure to function properly.

Mixed or combined: No minimum pressure is required, such as indirectly operated valves. In these valves, the opening command is performed in two steps: first, after emptying the upper pressure of the large diaphragm, the pressure of the lower diaphragm opens it to open. During the second opening stage, the piston is attached to the large diaphragm by a spring, which speeds up the pressure when the diaphragm is opened.

How do proportional valves work?

Proportional electric valves allow the control and adjustment of fluids based on electrical signals, which can be current or voltage. The use of these valves in the pilot electronics increases the level of precision, thus expanding the applicable field.

Its main application is to control the precision and force, since it is proportional to the movement and precise, which allows a more precise control of the fluid flow.

These can be classified as follows:

Flow control valve: This parameter is continuously adjusted between the null and maximum value. It is also a sliding valve, dispenser and offers a variety of methods and positions.

Pressure control valve: Continuously adjust the output of this parameter between the minimum and maximum values ​​equal to the inlet pressure.

Differences between motor-driven electric valves and solenoid electric valves

The valve is the most essential adjustment device in the industry, thanks to its design and materials. Its function is to open and close; Connection and disconnection; Adjustment, modulating or separation of liquids and gases. Usually, the valve has two parts: drive or actuator and housing.

While the housing controls the amount of fluid that passes through it, the driver or actuator is responsible for applying the force necessary to move the housing to make adjustments.

Among the actuators you will find solenoid and motor.

Solenoids can generate a very uniform and strong magnetic field inside and are very weak devices outside. Thanks to this magnetic field, we can perform linear motion on iron shafts, which act on the valve housing.

Motor-operated electric valves generally use single-phase or direct current AC motors, but you can find other types of motors depending on the precision and force required.

Application of motor and solenoid-driven valves.

The purpose of the solenoid operated valve is the same as that of the motor operated valve, but one system or another must be chosen depending on the purpose and application of the valve.

Generally, motor operated valves are chosen for applications with low power consumption. Motor-operated valves only use energy when they change from one state to another, so they can stop at a certain position. In addition, for large valves, it is better to use a motor-operated valve, since it is much easier to implement.

On the contrary, solenoid valves are recommended for applications where the priority is a transition speed, since the linear motion produced by the solenoids is very fast. Similarly, this device is commonly used for small valves, because it is easy to implement.

What characteristics should be taken into account when choosing a valve?

·         Flow control.
·         Pressure range you want to operate.
·         Fluid and external temperature
·         Pipe or connection type
·         Electrical characteristics of the valve
·         Power required
·         Working speed
·         Operating period

As already mentioned, the use of one or more techniques will depend on the final application and the required functionality.

Motorized electric valves are commonly used in irrigation systems with flow or pressure control, high-pressure hydraulic lines, dental equipment and vehicle suspension systems. Solenoid valves are very common in commercial refrigeration systems, industrial pneumatic systems, compressors, coffee makers and boiler control.

Each technology has the following characteristics:

Motor operated valve:

·         Variable opening (flow) proportional to the control signal
·         No minimum working pressure is required.
·         Low energy consumption
·         The valve position is maintained in case of power shortage.

Solenoid valve:

·         High conversion speed
·         Simple architecture
·         Low cost.