How to Solve Solenoid Valve Failure
As an actuator for automated meters, solenoid valves have seen dramatic increases in usage in recent years. This paper analyzes the main characteristics of the solenoid valve, and focuses on the perspective of the application of the domestic development of mature technology, a brief summary of the refinement, intelligence, generalization, and specialization direction were investigated and slightly affect the development of electromagnetic valve technology Social factors are discussed.
Solenoid valves generally have a small flow coefficient and the working pressure difference is small. For example, the general 25-gauge solenoid valve has a much smaller flow coefficient than the 15-bore electric ball valve. Solenoid valves are driven by solenoids and are easily damaged by voltage surges. The equivalent of the switch is to open and close two roles. The electric valve is usually driven by a motor and is relatively resistant to voltage shocks. Solenoid valves are quick-opening and fast-closing. They are generally used in small flow and small pressure, where the switching frequency is large, and the electric valve is the opposite. The opening degree of the electric valve can be controlled. The state is on, off, half-open and half-close. It can control the flow of medium in the pipeline and the solenoid valve cannot meet this requirement.
The main features of the solenoid valve
(1) External leakage is blocked, internal leakage is easy to control, and safety is used. Internal and external leaks are elements that endanger safety. Other self-controlled valves usually extend the valve stem and control the rotation or movement of the valve core by electric, pneumatic, and hydraulic actuators. This must solve the problem of external leakage of the valve stem dynamic seal during long-term operation; only the solenoid valve is operated by the electromagnetic force acting on the core sealed in the magnetic isolation sleeve of the electric control valve, there is no dynamic seal, so the leakage is easy to block. . Electric valve torque control is not easy, easy to produce internal leakage, and even pull off the stem head; the structure of the solenoid valve is easy to control the internal leakage until it is reduced to zero. Therefore, the solenoid valve is particularly safe to use, especially for corrosive, toxic or high-low temperature media.
How to Solve Solenoid Valve Failure
(2) The system is simple, then it is connected to the computer, the price is low and modest. The solenoid valve itself has a simple structure and a low price, and is easier to install and maintain than other types of actuators such as regulating valves. What is even more remarkable is that the self-contained system is much simpler and the price is much lower. Since the steam solenoid valve is a switch signal control, it is very convenient to connect with an industrial control computer. In today's era of widespread computer availability and sharply lower prices, the advantages of solenoid valves are even more pronounced.
(3) Action express, small power, light weight. Solenoid valve response time can be as short as several milliseconds, and even pilot solenoid valves can be controlled within tens of milliseconds. Because of self-looping, it reacts more sensitively than other self-controlled valves. Well-designed solenoid valve coil power consumption is very low, is an energy-saving product; can also be achieved simply trigger action, automatically maintain the valve position, usually does not consume electricity. The electromagnetic valve has a small size, which saves space and is light and beautiful.
(4) The adjustment accuracy is limited and the applicable medium is limited. Gas solenoid valve usually only two kinds of switch state, the valve can only be in two extreme positions, can not be continuously adjusted, (a lot of new ideas trying to break through, but are still in the experimental trial phase) so the adjustment accuracy is also subject to certain restrictions. Solenoid valves have high requirements for the cleanliness of the medium. The granular media cannot be applied. If impurities are present, they must be filtered out first. In addition, viscous media cannot be used, and the specific product is suitable for a relatively narrow range of media viscosity.
(5) Models are diverse and widely used. Although the solenoid valve is inherently inadequate, the advantages are still very prominent, so it is designed into a wide variety of products to meet a variety of different needs and uses are extremely wide. The progress of solenoid valve technology is also centered around how to overcome congenital deficiencies and how to better develop the inherent advantages.
Precautions when selecting a type
One: Applicability
The fluid in the tubing must be the same as that used in the selected solenoid series model. The temperature of the fluid must be less than the calibrated temperature of the selected solenoid valve.
Solenoid valves allow the viscosity of liquids to be generally below 20CST, and should be indicated when more than 20CST. Working pressure difference, the maximum pressure difference in the pipeline is less than 0.04MPa should be used such as ZS, 2W, ZQDF, ZCM series of direct-acting and step-by-step direct-acting; minimum operating pressure difference is greater than 0.04MPa can use the pilot type (pressure Differential type) Solenoid valve; the maximum working pressure difference should be less than the maximum calibration pressure of the solenoid valve; the general electromagnetic valve is one-way operation, so pay attention to whether there is back pressure difference, if installed check valve. When the fluid cleanliness is not high, a filter should be installed in front of the solenoid valve. Generally, the electromagnetic valve requires better cleanliness of the medium. Pay attention to the flow aperture and the nozzle diameter; solenoid valve is generally only two-way control switch; conditions allow to install the bypass pipe, easy to repair; have water hammer phenomenon to customize the solenoid valve opening and closing time adjustment. Pay attention to the influence of ambient temperature on the solenoid valve. The current and power consumption of the power supply should be selected according to the output capacity. The power supply voltage is generally allowed to be ±10%. It must be noted that the VA value at the time of AC start is high.
How to Solve Solenoid Valve Failure
Second, reliability
Solenoid valves are classified into two types: normally closed and normally open. Normally selected are normally closed, open when power is on, and turned off after power off. However, the normally open type should be selected when the opening time is very long and the time is very short. Life test, the factory is generally a type test project, to be exact, there is no professional standard for solenoid valves in China, so choose a solenoid valve manufacturer with care. When the operation time is very short, the direct-acting type is generally selected, and the large-caliber selection is used for the fast series.
Third, security
General solenoid valve is not waterproof, please use waterproof type when conditions do not allow, factory can be customized. The highest nominal pressure of the solenoid valve must exceed the maximum pressure in the pipeline, otherwise the service life will be shortened or other unexpected situations will occur. The corrosive liquid should be of all stainless steel type, and the strong corrosive fluid should use plastic king. Explosion-proof products must be selected for explosive environments.
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