Solenoid valve working principle

Types of Solenoid Valves

The function of a solenoid valve is to control the flow of liquids and gases. They usually come in different types.

• Direct acting solenoid valve: A direct acting solenoid valve does not need a particulate body element. It is designed to control minute fluid flow or working pressure.
• Internally piloted solenoid valve: This type of solenoid valve uses the pressure of the medium to move itself. It can easily open or close a small cavity on the valve body.
• Externally piloted solenoid valve: The externally piloted solenoid valve has an external source of pressure. This large source of pressure enables it to function properly. It controls the flow of various pressures with ease.
• Direct acting normally closed solenoid valve: The normally closed solenoid valve allows the flow of liquid or gas when electric current passes through the valve's coil. When the electric current stops flowing, the valve closes, and the fluid passage is blocked.
• Direct acting normally open solenoid valve: The normally open solenoid valve coil generates an electromagnetic force that pulls the valve seat. This permits the fluid to get through the valve. When electric current flows through the coil, the valve seat is pushed back, and the valve closes. This valve is rarely used in the industry.
• 3-way solenoid valve: The 3-way solenoid valve controls the flow of two ways from a single source. It is a normally closed valve with two inlets and one outlet. The 3-way solenoid valve is used for automatic switching, distribution, mixing, and pressure relief.
• 5-way solenoid valve: The 5-way solenoid valve is used to control double acting cylinders and single reverse function. It has two inlets, one outlet, and four passages.

Specifications and maintenance of solenoid valve working principle

Specifications

• Functions:

  Solenoid valves control different functions, like stopping fluid flow, allowing it to pass, changing flow direction, or mixing fluids. They can also control the on-off functions of a system. Therefore, understanding the working principle of a solenoid valve is key to understanding how it controls the flow of liquids and gases in various applications.

• Actuation type:

  There are two main types of solenoid valves. An electropneumatic solenoid valve is controlled by electricity and uses air pressure to move parts. An electric electrovalve has no moving parts. Instead, it has electronic circuits that directly control the flow of fluid, making it simpler and more efficient.

• Function elements:

  The main parts of solenoid valves are coils, cores, sleeve, and spring. The coil is a wire loop that makes magnetic fields when electricity flows through it. The core, made of magnetizable material, moves within the coil due to magnetism. It can be an open core or a normally closed or opened configuration. The sleeve is the outer part that holds the core. The spring pushes the core back to its original position. Their working principle is the attraction or repulsion of magnetism. The magnetic force moves parts, which leads to the opening or closing of seats and comes to the sealing elements. This movement changes the flow status.

• Normally open /N.O. & normally close/ N.C.:

  Usually open solenoid valves let fluid flow pass when not energized. They stop the flow when energized. Normally closed solenoid valves do the opposite.

• Single acting /Spring return:

  Spring return solenoid valves have a spring that returns the core to its position when power is off.

• Mounting:

  Mounting options let users fit the solenoid valve into liquid or gas lines as needed.

• IP ratings:

  IP rating indicates the waterproof and dustproof levels of the solenoid valve. A higher IP rating means better protection.

Maintenance

• Routine inspection:

  Regularly check for signs of valve damage, such as cracked or worn parts. Listen for unusual sounds during operation.

• Lubrication:

  Appropriately lubricate the solenoid valve and ensure the grease does not attract dust.

• Cleaning:

  Clean the outside of the solenoid valve and avoid the ingress of dirt and impurities into the inside.

• Fastening:

  Periodic checking and fastening of the solenoid valve mounting brackets/director if the connections are loose.

Scenarios of solenoid valve working principles

The working principle of a solenoid valve is applied across many industries and sectors. Some of the common applications include the following.

General fluid control

Solenoid valves are widely used in the oil and gas industry to control the flow of fluids. For example, in pipelines, solenoid controls the opening and closing of the fluid flow. It assists in regulation, automation, and timely shut-off of the flow of fluids in the system.

Automotive Applications

Automobile manufacturers employ solenoid valves in various systems of the car. This includes but isn't limited to the transmission system, fuel system, and air conditioning system. The fuel injection system employs solenoid valves to regulate the flow of fuel. Thus, ensuring optimal combustion of the engine and performance of the vehicle. In the air conditioning system, the valve controls the refrigerant's flow. Enabling proper functioning of the system and the vehicle's ride comfort.

Medical devices

Medical devices and equipment also use solenoid control. These devices precisely control the flow of air, gas, or liquid. For example, in inhalers or oxygen masks, the valve regulates the flow of oxygen to the patient. Ensuring the patient receives the required dosage. Another example is in dialysis machines. Here, the valve controls blood flow and the filtration of human blood through the machine.

How to choose solenoid valve working principles

When selecting solenoid valves for application, a number of factors should be considered, including the body and seal material, temperature, voltage, media, wattage, pressure, flow rate, and function.

• Body and seal material

  Solenoid valves are made from different body materials, such as brass solenoid valve, plastic, carbon steel, and stainless steel, each suitable for particular media. For instance, carbon steel or brass would be suitable for use with compressed air. Additionally, the requirement for low noise might warrant the use of plastic as the body material. Media compatibility also affects seal material choices, which include rubber, VTFE, NBR, etc. For example, NBR seals are ideal for working with water, while VTFE seals excel in high-temperature oil applications. Ensuring compatibility between media and seal materials is crucial for avoiding leakage and valve failure.

• Temperature

  Every solenoid valve has temperature limitations dictated by its construction and sealing materials. Operating beyond these limits can result in damage or malfunction. For example, high-temperature solenoid valves show that they can function normally in high-temperature places, while low-temperature valves work in low-temperature places.

• Voltage

  Solenoid valves require specific operating voltages (12V, 24V, 110V, etc.) to ensure correct function. Providing the proper voltage is essential for the solenoid valve's performance.

• Media

  Solenoid valves must be compatible with the media they control (air, water, oil, etc.). Failure to match valve construction and materials with the media can lead to damage or leakage.

• Wattage

  The wattage requirements of a solenoid valve represent the power needed for proper operation. Different solenoid valves may have varying wattage demands, which should be considered during installation and power supply selection.

• Pressure

  Whether operating under high or low pressure, solenoid valves must be capable of handling the system's pressure levels. High-pressure solenoid valves are designed to function in pressurized environments, while low-pressure valves are suitable for handling low-pressure conditions.

• Flow rate

  Solenoid valves are available in different flow rates to meet specific system requirements. The flow rate determines the valve's capacity to permit fluid passage. Selecting a solenoid valve with the appropriate flow rate is essential for ensuring proper system function and performance.

• Function

  Solenoid valves serve various functions, such as on/off control (normally closed or normally open) and pressure regulation. It is important to choose the right type of solenoid valve to meet the specific application needs. For example, normally closed solenoid valves are designed to be closed when not energized, allowing for on/off control of fluid flow. On the other hand, normally open solenoid valves are open in their default state and close when energized. Normally open solenoid valves are suitable for specific applications that require a direct flow path when de-energized. By understanding the different functions and operating principles of solenoid valves, the appropriate valve can be selected for the desired control function.

Solenoid valve working principle FAQ

Q1: How does the solenoid valve control the flow of water?

A1: Water flow can be controlled by a solenoid valve through a pneumatic control system. Compressed air can be used to power the valve, which in turn will allow for any adjustments that might be necessary to ensure proper functioning of this device with regards to controlling its own internal mechanisms utilizing only ''Solenoids'' as an external means of stimulation.

Q2: What are the advantages of solenoid valves?

A2: The advantages of solenoid valves include fast switching speed, long life, convenient automatic control, and high reliability. Solenoid valves can be opened and closed quickly and are responsive, so they are suitable for occasions that require frequent switching. Solenoid valves have few mechanical parts, and the contactless electromagnetic drive reduces mechanical wear and tear, thus allowing for longer service life. Solenoid valves can be connected to other devices to form an automatic control system, making convenient automatic control possible. In addition, the reliability of solenoid valves is high, so they are suitable for use in equipment and systems that require high reliability.

Q3: What is the solenoid valve made of?

A3: A solenoid valve is made up of several components, including the body, solenoid coil, plunger, spring, and sealing element. The body of the valve provides an open passage for fluids to flow through, while also housing its other parts. In addition to being able to house everything else that makes up a valve, it also gives shape and strength to hold whatever is passing through it. The components of a solenoid valve are often made of durable materials like brass, stainless steel, or polypropylene, which can withstand harsh environments and long-term use.

Q4: Are solenoid valves AC or DC?

A4: Solenoid valves are generally classified into two types according to the applicable voltage, namely direct current solenoid valves and alternating current solenoid valves. DC solenoid valves are powered by direct current, while AC solenoid valves are powered by alternating current.