1. Switch form:
The solenoid valve is driven by the coil and can only be turned on or off. The switching time is short.
The drive of the electric valve is generally driven by a motor. It takes a certain amount of time to simulate the opening or closing action, and can be adjusted.
2. Nature of work:
Solenoid valves generally have a small flow coefficient and a small difference in working pressure. For example, a general 25-caliber solenoid valve has a smaller flow coefficient than a 15-caliber electric ball valve. The solenoid valve is driven by an electromagnetic coil and is relatively easily damaged by voltage surges. Equivalent to the role of the switch, is the role of opening and closing.
The drive of the electric valve is generally a motor, which is more resistant to voltage shock. The solenoid valve is fast open and fast closed. It is generally used in small flow and small pressure, and the electric switch is required in the place where the switching frequency is large. The opening of the electric valve can be controlled. The state has open, closed, half open and half closed, which can control the flow of the medium in the pipeline and the solenoid valve can not meet this requirement.
Solenoid valves can be reset by general power failure. For such functions, electric valves require a reset device.
3. Applicable process:
Solenoid valves are suitable for some special process requirements, such as leakage, special fluid media, etc., which are more expensive.
Electric valves are generally used for adjustment and also have a switching quantity, such as: fan coil end.
Solenoid valves, as an actuator for automated meters, have increased dramatically in recent years. This paper analyzes the main characteristics of the solenoid valve, and focuses on the application of the brief analysis of the development of domestic mature technology in the simplified, intelligent, generalized, specialization direction and slightly affect the development of electromagnetic valve technology. Social factors are discussed.
The main features of the solenoid valve
(1) The external leakage is blocked, the internal leakage is easy to control, and the use is safe. Internal and external leakage is an essential element of safety. Other self-control valves typically extend the valve stem and control the rotation or movement of the spool by an electric, pneumatic, hydraulic actuator. This must solve the problem of external leakage of the long-acting valve stem dynamic seal; only the electromagnetic valve is applied by the electromagnetic force on the iron core sealed in the magnetic isolation valve of the electric control valve, there is no dynamic seal, so the external leakage is easy to block . The electric valve torque control is not easy, it is easy to produce internal leakage, and even the stem of the valve stem is broken; the structure of the electromagnetic valve is easy to control the internal leakage until it drops to zero. Therefore, solenoid valves are particularly safe to use, especially for corrosive, toxic or high temperature media.
(2) The system is simple, then the computer is connected, and the price is low. The solenoid valve itself is simple in structure and low in price, and is easy to install and maintain compared to other types of actuators such as regulating valves. What's more remarkable is that the self-control system is much simpler and the price is much lower. Since the solenoid valve is controlled by the switching signal, it is very convenient to connect with the industrial computer. In today's era of computer popularization and price drop, the advantages of solenoid valves are even more obvious.
(3) The action express, the power is small, and the shape is light. The solenoid valve response time can be as short as a few milliseconds, even a pilot solenoid valve can be controlled in tens of milliseconds. Due to the self-contained loop, it is more sensitive than other self-controlled valves. The well-designed solenoid valve coil has low power consumption and is an energy-saving product. It can also be used to trigger the action and automatically maintain the valve position, and it does not consume electricity at all. The solenoid 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. Solenoid valves usually only have two states of switching. The valve core can only be in two extreme positions and cannot be continuously adjusted. (There are many new ideas for breaking through, but they are still in the trial and trial stage), so the adjustment accuracy is also limited.
Solenoid valves have high requirements on the cleanliness of the medium. Granular media cannot be used. If it is an impurity, it must be filtered first. In addition, viscous media is not suitable, and the viscosity range of the medium for a particular product is relatively narrow.
(5) Various models and wide range of uses. Although the solenoid valve is inherently insufficient, the advantages are still outstanding, so it is designed into a wide variety of products to meet a variety of needs, and is extremely versatile. The advances in solenoid valve technology are also centered around how to overcome the inherent deficiencies and how to better develop their inherent advantages.
First, the product selection points
1. The main control parameters of the solenoid valve are the diameter, the design nominal pressure, the allowable temperature range of the medium, and the interface size.
2. The solenoid valve is used to push the valve to open and close. It is usually used in two-position control with a diameter of less than 40mm, especially for connecting, cutting or switching the gas path and liquid path.
3. The sealing performance of the valve is one of the main indicators for evaluating the quality of the valve. The sealing performance of the valve mainly includes two aspects, namely internal leakage and external leakage. The internal leakage refers to the degree of sealing of the medium between the valve seat and the closing member. External leakage refers to the leakage of the valve stem packing part, the leakage of the middle port gasket and the leakage of the valve body due to casting defects. External leakage is not allowed.
4. The main advantages of the solenoid valve are small size, reliable operation, convenient maintenance and low price. When selecting, you need to pay attention to the choice of normally open or normally closed according to the process requirements.
Second, construction and installation points
1. The installation position and height of the valve must conform to the design requirements of the mouth direction, and the connection should be firm and tight.
2. The visual inspection must be carried out before the valve is installed. The nameplate of the valve should comply with the current national standard GB12220 “General Valve Marking”.
Third, the implementation of standards
GB/T13927-92 "General Valve Pressure Test"
JB/T8528-1997 "Technical conditions for ordinary valve electric devices"
GB12220-89 "General Valve Mark"
GB50243-2002 "Code for Construction Quality Acceptance of Ventilation and Air Conditioning Engineering"
GB50242-2002 "Code for acceptance of construction quality of building water supply and drainage and heating engineering"
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