products in the market is increasing day by day, and it has undoubtedly become one of the products in fluid control automation. According to the opening working form of the solenoid valve, it can be divided into two commonly used major categories: pilot-operated solenoid valves and direct-acting solenoid valves. However, if the selection is inappropriate, it can easily lead to situations such as the solenoid valve not working, and at the same time, it will have a certain impact on the safety of the working conditions and applications. So how can we distinguish the differences between the two and their respective characteristics so that they can be better applied? This article provides a detailed introduction. Please refer to the following content
The differences between direct-acting solenoid valves and pilot-operated solenoid valves
Pressure resistance: The pilot-operated solenoid valve can withstand greater hydraulic pressure than the straight-through solenoid valve.
Response time: The start-up speed of direct-acting solenoid valves is faster than that of pilot-operated ones, and they are mostly used in places where rapid cut-off is required. Because in a pilot-operated solenoid valve, the small valve opens first and the main valve opens later when powered on, while in a direct-acting solenoid valve, the main valve opens directly.
Flow capacity: The flow capacity of pilot-operated solenoid valves is larger than that of direct-acting ones. Generally, the CV value can reach over 3, while the CV value of direct-acting solenoid valves is usually less than 1.
Power and loss: The power and loss of direct-acting solenoid valves are greater than those of pilot-operated ones.
The requirement for medium cleanliness: Pilot-operated solenoid valves have relatively high requirements for the purity of the flowing medium, while direct-acting valves are not as strict.
Direct-acting solenoid valve
Direct-acting solenoid valves are generally used in small-diameter and low-pressure environments. When this type of valve is opened, it does not require the minimum pressure of the medium and starts at zero pressure. Therefore, compared with pilot-operated solenoid valves, its start-up speed is faster, making it particularly suitable for places that require rapid shut-off.
: Its power consumption is higher than that of pilot-operated solenoid valves, typically ranging from 5 to 20 watts. High-frequency power-on can easily burn out the coil, but it is easy to control and has a wide range of applications. It can operate normally under vacuum, negative pressure and zero pressure conditions, but the diameter of the passage generally does not exceed 50mm.
Pilot-operated solenoid valve
Pilot-operated solenoid valves are generally used in large-diameter and high-pressure applications. When this type of valve is opened, the minimum pressure of the solenoid valve must not be lower than 0.03MPa. There must be a pilot pressure; otherwise, it cannot be opened. In addition, the flow capacity of pilot-operated solenoid valves is greater than that of direct-acting solenoid valves, and generally, the CV can reach above 3. The purity requirement for compressed air is relatively high, but for direct-acting ones, it is not so strict.
: Small electromagnetic head, low power consumption, 0.1-0.2w, can be powered on frequently and for a long time without burning out, and energy-saving. The upper limit of the fluid pressure range is relatively high, and it can be installed arbitrarily (customization required), but it must meet the fluid pressure difference conditions. However, impurities in the liquid are prone to clogging the pilot valve holes and are not suitable for liquid use.
Take the normally closed solenoid valve as an example. The action process is:
(1)When the solenoid valve is energized, it is as shown in the following figure.
The electromagnetic force generated when the coil is energized causes the pilot valve to open, and the medium flows to the outlet. The pressure in the upper chamber of the main valve drops rapidly, forming a pressure difference in the upper and lower chambers of the main valve to overcome the spring force and move upward accordingly. The main valve opens, the medium flows, and the solenoid valve opens.
(2) When the solenoid valve loses power, it is as shown in the following figure.
When the solenoid valve coil is de-energized, the electromagnetic force disappears. Under the action of the spring force, the moving iron core returns to its original position, closing the pilot valve. The medium flows in through the flow guide hole. The pressure in the upper chamber of the main valve core increases and it moves downward under the action of the spring force, closing the main valve. The medium flows off and the solenoid valve is closed.
Above is The differences between direct-acting solenoid valves and pilot-operated solenoid valves content, to learn more related information are available at https://www.joosungauto.com/.
