Electromagnetic valves can be divided into three categories in principle: direct acting, step-by-step direct acting, and pilot operated. And from the differences in valve disc structure and material, as well as the differences in principle, it can be divided into six sub categories: direct acting diaphragm structure, step-by-step direct acting diaphragm structure, pilot diaphragm structure, direct acting piston structure, step-by-step direct acting piston structure, and pilot piston structure.
1. Indirect pilot solenoid valve
This electromagnetic valve is composed of a channel combination formed by connecting the pilot valve and the main valve core; The normally closed type is in a closed state when not powered on. When the coil is energized, the magnetic force generated causes the moving iron core and the static iron core to be attracted, the pilot valve port opens, and the medium flows towards the outlet. At this time, the pressure in the upper chamber of the main valve core decreases, lower than the pressure on the inlet side, forming a pressure difference that overcomes the resistance of the spring and moves upwards, achieving the purpose of opening the main valve port and allowing the medium to flow. When the coil loses power, the magnetic force disappears, and the moving iron core resets and closes the pilot port under the action of spring force. At this time, the medium flows into the balance hole, and the pressure in the upper chamber of the main valve core increases. Under the action of spring force, it moves downward and closes the main valve port. The principle of open form is exactly the opposite.
Principle: When powered on, the electromagnetic force opens the pilot hole, causing a rapid decrease in pressure in the upper chamber, creating a high and low pressure difference around the open part. The fluid pressure drives the open part to move upwards, and the valve opens; When the power is cut off, the spring force opens the pilot hole, and the inlet pressure quickly forms a pressure difference of lower and higher around the closing valve through the bypass hole. The fluid pressure drives the open valve to move downwards and open the valve.
Features: Small size, low power, high upper limit of fluid pressure range, can be installed arbitrarily (customized), but must meet the conditions of fluid pressure difference.
2. Stepwise direct acting solenoid valve
This type of valve adopts a combination of primary and secondary opening, and the main valve and pilot valve step by step to directly open the main valve port with electromagnetic force and pressure difference. When the coil is energized, electromagnetic force is generated to attract the moving iron core and the stationary iron core. The pilot valve port opens and the pilot valve port is located on the main valve port. The moving iron core is connected to the main valve core. At this time, the pressure in the upper chamber of the main valve is unloaded through the pilot valve port, and under the simultaneous action of pressure difference and electromagnetic force, the main valve core moves upward, opening the flow of medium in the main valve. When the coil loses power, the electromagnetic force disappears. At this time, the moving iron core closes the pilot valve hole under the action of its own weight and spring force. At this time, the medium enters the upper chamber of the main valve core in the balance hole, causing the pressure in the upper chamber to increase. At this time, the main valve is closed under the action of spring reset and pressure, and the medium is cut off. Reasonable structure, reliable action, and reliable operation even at zero pressure difference. For example: ZQDF, ZS, 2W, etc.
Principle: It is a combination of direct action and pilot type principle. When there is no pressure difference between the inlet and outlet, after being energized, the electromagnetic force directly lifts the pilot small valve and the main valve closure part upwards, and the valve opens. When the inlet and outlet reach the starting pressure difference, after being energized, the electromagnetic force leads the small valve, and the pressure in the lower chamber of the main valve increases while the pressure in the upper chamber decreases, thereby using the pressure difference to push the main valve upwards; When the power is cut off, the pilot valve uses spring force or medium pressure to push the closing part downwards, causing the valve to close.
Features: It can also operate under zero pressure difference, vacuum, and high pressure, but with high power, requiring horizontal installation.
3. Direct acting solenoid valve
There are two types: normally closed and normally open. When the normally closed type is powered off, it is in a closed state. When the coil is energized, electromagnetic force is generated, causing the moving iron core to overcome the spring force and directly open the valve with the static iron core, and the medium is in a path; When the coil loses power, the electromagnetic force disappears, and the moving iron core resets under the action of spring force, directly closing the valve port and preventing the medium from flowing. The structure is simple, the action is reliable, and it works normally under zero pressure difference and micro vacuum. The normally open type is exactly the opposite. If less than φ Electromagnetic valve with a flow path of 6.
Principle: When the normally closed type is energized, the electromagnetic coil generates electromagnetic force to lift the open part from the valve seat, and the valve opens; When the power is cut off, the electromagnetic force disappears, and the spring presses the open part against the valve seat, causing the valve to open. (The opposite is true for normally open models)
Features: It can work normally under vacuum, negative pressure, and zero pressure, but the diameter generally does not exceed 25mm.
4、 The difference between solenoid valves and electric valves
Electric valves drive the valve stem through a motor, which drives the valve core to move and achieve fluid flow through or through; An electromagnetic valve is composed of an electromagnetic coil (electromagnet), a valve core, and a valve body. When the electromagnetic coil is powered on or off, it drives the valve core to move, allowing fluid to pass through the valve body or be cut off;
Electric valves are not only suitable for controlling general fluid media, but also especially suitable for controlling pulp, sewage, media containing fibers and small solid particles. They do not require high cleanliness of the media and have a higher leakage rate compared to solenoid valves.
The driving force of electric valves is generally electric motors, which are more resistant to voltage shocks and have a large driving force. They can control large diameter valves, and electric valves can adjust the flow rate of pipelines, especially suitable for large diameter pipelines or places that require adjustment of pipeline flow rate;
The drive of an electromagnetic valve is through an electromagnetic coil, which has a small driving force and is relatively easy to be damaged by voltage shocks. It is generally suitable for pipelines with a diameter smaller than DN50 and below. The action time during opening and closing is short, and there is a dedicated high-frequency electromagnetic valve, which is especially suitable for use in pipelines with high action frequency or requiring short switching time;
Electromagnetic valves are suitable for a wide range of media, including acid, alkali, water, gas, oil, steam, and other media. However, there are high requirements for the viscosity and cleanliness of the media. Before installing the electromagnetic valve, a filter should be installed to ensure its normal operation, low leakage rate, and high safety;
5、 Technical specifications of solenoid valves
1. Immersion in water
The inlet valve is immersed in water with a depth of 10 ± 1cm and a temperature of 20 ± 5 ℃ for 8 hours. The surface water droplets are removed and wiped dry, with an insulation resistance greater than 10M Ω
2. Temperature changes
Place the inlet valve at 80 ± 2 ℃ for 1.5 minutes and at room temperature of 20 ± 2 ℃ for 1.5 minutes; Leave it at -20 ± 2 ℃ for 30 minutes for one cycle.
3. Durability
Apply water pressure of 0.02, 0.3, and 0.78Mpa to the inlet of the inlet valve, and apply rated voltage of 5S ON and 5S OFF to the coil. After 10000, 30000, and 10000 cycles of operation, it meets the requirements.
4. Noise
The inlet valve is not open to water, and the rated voltage is applied to measure the distance r of 0.5m at a sound power level of 50dB.
5. Continuous power on
When the inlet valve is not connected to water and the rated voltage is applied for 12 hours, the valve body will not deform or burn out.
6. Interlayer insulation
Under a peak voltage of 1500V, a repetition frequency of 25Hz, a pulse front of 0.2-3us, and a pulse width of 40us, the waveform is stable and shows no abnormalities. Original address: http://www.pikacn.com/news/201611/5326.html
7. Coil temperature rise
When the inlet valve is in a state of no water supply, the coil is subjected to rated voltage. After the temperature stabilizes, the coil temperature rise is less than 70K.
8. Electrical strength
Apply AC2500V to the conductive and non-metallic parts for 1 minute without flashover or breakdown.
9. Insulation resistance
The insulation resistance between the conductive and non-metallic parts is greater than 100M Ω.
10. Water pressure resistance
Apply static water pressure of 0.02Mpa, 0.8Mpa, and 1.96Mpa to the inlet, and there should be no leakage within 1min, 1min, and 5min.
11. Water pressure resistance
Apply static water pressure of 0.02Mpa, 0.8Mpa, and 1.96Mpa to the inlet, and there should be no leakage within 1min, 1min, and 5min.
12. Startup characteristics
Apply 0.8Mpa water pressure to the inlet and 85% of the rated voltage to the coil for on/off operation, with no abnormalities.
13. Flow range
As needed (usually 0.35-35L/min).
14. Insulation level
E level.
15. Working voltage range
± 15% of rated voltage.
16. Action pressure range
0.02~1.0Mpa (can also be a pressure free inner core structure valve as needed, which is mostly used for container drain or outlet valves).
17. Rated voltage
According to requirements (generally DC 6V, 12V, 24V, 110V; AC 6V, 12V, 24V, 110V, 220V)
6、 The identification meaning of solenoid valves
The meaning of the name of electromagnetic valve (also known as inlet valve, electromagnetic inlet valve, water solenoid valve, feedwater solenoid valve, no pressure discharge solenoid valve, etc.) is as follows: an example is given to illustrate "FCD-270B".
1. Letter "B"
"B" is the internal number of the production factory.
2. Number "270"
"270" represents the relative angle between the outlet (i.e. the plug connected to the external circuit or power supply) and the water inlet (there are only four relative angles between the inlet and outlet of the inlet solenoid valve, namely 0 º, 90 º, 180 º, and 270 º. Specifically, when looking down at the coil, with the center of the coil as the origin, the counterclockwise relative angle between the inlet axis of the solenoid valve and the terminal means that when looking down at the coil, the inlet is facing itself, and the outlet is also facing itself, which is 0 degrees. The outlet facing right is 90 degrees, the outlet facing outward is 180 degrees, and the outlet facing left is 270 degrees);
3. Letter "D"
"D" represents single pass (which indicates the number of water outlets of the inlet solenoid valve. A single universal "D" represents only one outlet, a double universal "S" represents two outlets, such as FCS-0A, FPS-180B, etc., and three or more outlets are called multiple universal numerical representations, such as FP3-180C, FC4-0D, etc. Currently, the most common water outlets on the market are four, namely FC4 or FP4);
4. Letter "C"
"C" represents "vertical" (meaning that the relative angle between the inlet and outlet of the inlet solenoid valve is vertical, and there are only two types of relative angles between the inlet and outlet of the inlet solenoid valve, namely vertical and parallel. The vertical is represented by the letter C, and the parallel is represented by the letter P, such as F "C" D-270B and parallel F "P" D-90A);
5. Letter "F"
"F" represents "valve", and all inlet solenoid valves are named starting with "F";