Solenoid valve principle is divided into three categories: direct acting, step by step direct acting, pilot type. From the difference of valve disc structure, material and principle, it is divided into six sub-categories: direct acting diaphragm structure, step direct acting diaphragm structure, pilot diaphragm structure, direct acting piston structure, step direct acting piston structure, pilot piston structure.

1, indirect pilot solenoid valve

The solenoid valve is composed of a pilot valve and a main valve core connected to form a channel; Normally closed type is closed when there is no power. When the coil is energized, the magnetic force generated makes the moving core and the static core pull, the pilot valve port is opened, and the medium flows to the outlet. At this time, the pressure on the upper chamber of the main valve core is reduced, lower than the pressure on the inlet side, forming a pressure difference to overcome the spring resistance and then move upward to achieve the purpose of opening the main valve port, and the medium flows. When the coil is powered off, the magnetic force disappears, the moving iron core resets and closes the pilot port under the action of the spring force. At this time, the medium flows into the balance hole, the pressure on the upper chamber of the main spool increases, and moves downward under the action of the spring force to close the main valve port. Normally open principle is the opposite.

Principle: When energized, the electromagnetic force opens the pilot hole, the upper chamber pressure drops rapidly, forming a low and high pressure difference around the open part, the fluid pressure pushes the open part to move upward, and the valve opens; When the power is off, the spring force opens the pilot hole, and the inlet pressure forms a low and high pressure difference around the valve closing part through the bypass hole rapidly, and the fluid pressure pushes the opening part to move down and open the valve.

Features: small size, low power, high upper limit of fluid pressure range, can be installed arbitrarily (need to be customized), but must meet the fluid pressure difference conditions.

2, step direct acting solenoid valve

This valve uses a primary opening valve and a secondary opening valve connected in one, the main valve and the pilot valve step by step to make the electromagnetic force and pressure difference directly open the main valve port. When the coil is energized, the electromagnetic force is generated to pull the moving core and the static core, the pilot valve port is opened and the pilot valve port is located on the main valve port, and the moving core is connected with the main valve core. At this time, the pressure of the main valve chamber is discharged through the pilot valve port, and the main valve is moved upward under the pressure difference and the electromagnetic force at the same time, the main valve media flow is opened. When the electromagnetic force disappears when the coil is powered off, the moving iron core closes the pilot valve hole under the action of self-weight and spring force. At this time, the medium enters the upper chamber of the main valve core in the balance hole, so that the pressure of the upper chamber increases. At this time, the main valve is closed under the action of spring return and pressure, and the medium is cut off. The structure is reasonable, the operation is reliable, and the work is also reliable at zero pressure difference. Such as: ZQDF, ZS, 2W, etc.

Principle: It is a combination of direct action and pilot principle, when there is no pressure difference between the inlet and the outlet, after the power is turned on, the electromagnetic force directly lifts the pilot small valve and the main valve closing part in turn, and the valve opens. When the inlet and outlet reach the starting pressure difference, after power, the electromagnetic force pilot small valve, the main valve lower chamber pressure rises, the upper chamber pressure drops, so as to use the pressure difference to push the main valve upward; When the power is off, the pilot valve uses spring force or medium pressure to push the closing part and moves downward to close the valve.

Features: Zero pressure difference or vacuum, high pressure can also be operated, but the power is large, it must be installed horizontally.

3, direct acting solenoid valve

There are normally closed type and normally open type two. The normally closed type is closed when the power is off, and the electromagnetic force is generated when the coil is energized, so that the moving core overcomes the spring force and the static core draws directly open the valve, and the medium is a path; When the coil is powered off, the electromagnetic force disappears, the moving core is reset under the action of the spring force, and the valve port is directly closed, and the medium is blocked. Simple structure, reliable operation, normal operation under zero pressure difference and micro vacuum. Normally open type is the opposite. If less than φ6 flow diameter solenoid valve.

Principle: When the normally closed type is energized, the electromagnetic force generated by the electromagnetic coil lifts the open part from the valve seat, and the valve opens; When the power is off, the electromagnetic force disappears, the spring presses the opening part on the seat, and the valve opens. (Normally open type is the opposite)

Features: It can work normally under vacuum, negative pressure and zero pressure, but the diameter is generally not more than 25mm.

Four, the difference between solenoid valve and electric valve

The electric valve drives the valve stem through the motor and drives the spool action to realize the passing or cutting of the fluid; Solenoid valve is composed of solenoid coil (electromagnet) and valve core and valve body, when the solenoid coil power or power off, drive the valve core action, so that the fluid 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, fibers and small solid particles of the medium, the cleanliness of the medium is not high, and the leakage rate is relatively higher than the solenoid valve.

The electric valve is generally driven by a motor, which is relatively resistant to voltage shock, and the driving force is large, which can control the valve of large caliber, and the electric valve can adjust the flow of the pipeline, especially suitable for the use of large caliber pipelines or places requiring the flow of the pipeline to be adjusted;

The solenoid valve is driven by the electromagnetic coil, the driving force is small, it is easy to be damaged by the voltage impact, generally suitable for pipelines with caliber less than DN50 and below, the operation time is short when switching, and there is a special high-frequency solenoid valve, especially suitable for the use of pipelines with high operating frequency or short switching time;

Solenoid valve suitable for a wide range of media, acid, lye, water, gas, oil, steam and other media can be used, but for the viscosity of the medium, the degree of cleanliness has high requirements, before the installation of the solenoid valve to install a filter to ensure the normal operation of the solenoid valve, low leakage rate, high safety;

Five, solenoid valve technical indicators

1. Soak in water

Soak the inlet valve in water with a water depth of 10±1cm and a water temperature of 20±5℃ for 8h, remove and wipe the surface water beads, and the insulation resistance is greater than 10MΩ

2. Temperature change

The inlet valve is placed at 80±2℃ for 1.5min and at room temperature at 20±2℃ for 1.5nim. It was placed at -20±2℃ for 30min as a cycle.

3. Durability

The water pressure of 0.02, 0.3 and 0.78Mpa is applied to the inlet of the inlet valve, and the rated voltage of the coil is applied for 5S ON and 5S OFF for 10000, 30000 and 10000 times, respectively.

4. Noise

The inlet valve is not open to water, the rated voltage is applied to measure the distance r is 0.5m, and the sound power level is 50dB.

5, continuous power

The inlet valve is not ventilated, the rated voltage is applied for 12h, and the valve body is not deformed or burned.

6, layer insulation

When the peak voltage is 1500V, the repetition frequency is 25Hz, the pulse front is 0.2~3us, and the pulse width is 40us, the waveform is stable and no abnormality is displayed. The original address: http://www.pikacn.com/news/201611/5326.html原文地址：http://www.pikacn.com/news/201611/5326.html

7, coil temperature rise

When the inlet valve is in the state of no water flow, the rated voltage is applied to the coil. After the temperature is stable, the coil temperature rise is <70K.

8. Electrical strength

AC2500V is applied to the conductive part and the non-metallic part, and there is no flashover and no breakdown for 1min.

9. Insulation resistance

The insulation resistance between the conductive part and the non-metallic part is >100MΩ.

10, water pressure resistance

The hydrostatic pressure of 0.02Mpa, 0.8Mpa and 1.96Mpa is applied to the water inlet respectively, and there is no leakage within 1min, 1min and 5min.

11, water pressure resistance

The hydrostatic pressure of 0.02Mpa, 0.8Mpa and 1.96Mpa is applied to the water inlet respectively, and there is no leakage within 1min, 1min and 5min.

12. Startup characteristics

The water inlet applies 0.8Mpa water pressure, and 85% of the rated voltage is applied to the coil for on-off without abnormality.

13. Flow range

According to the need (generally 0.35~35L/min).

14. Insulation grade

Grade E.

15, working voltage range

±15% of the rated voltage.

16, action pressure range

0.02~1.0Mpa(It can also be a non-pressure internal core structure valve according to needs, which is mostly used for container water discharge or outlet valves).

17, rated voltage

According to requirements (generally DC 6V, 12V, 24V, 110V; Ac 6V, 12V, 24V, 110V, 220V.)

Six, solenoid valve identification meaning

The meaning of the name of the solenoid valve (also known as water inlet valve, electromagnetic inlet valve, water solenoid valve, water supply solenoid valve, and non-pressure water discharge solenoid valve) is as follows: FCD-270B is an example.

1. The letter "B"

"B" is the internal number of the production plant itself.

2. Number "270"

"270" represents the relative Angle between the outlet (that is, the plug connected to the external < circuit or power supply >) and the water inlet (The relative Angle between the inlet and the outlet of the water inlet solenoid valve is only four angles, namely 0º, 90º, 180º, 270º, and it is determined as follows: Looking down the coil, with the coil center as the origin, the counterclockwise relative Angle between the solenoid valve inlet axis and the terminal, that is, looking down the coil inlet towards itself, the leading end is also towards itself is 0 degrees, the leading end is 90 degrees to the right, the leading end is 180 degrees, and the leading end is 270 degrees to the left);

3. The letter "D"

"D" stands for single pass (that is, indicates the number of water inlet solenoid valve outlet, only one outlet is a single universal "D", there are two outlets called double universal "S", such as FCS-0A, FPS-180B, etc. There are three or more water outlets called multiple universal digital representations such as FP3-180C, FC4-0D, etc. At present, the most water outlets on the market are four water outlets, that is, FC4 or FP4);

4. The letter "C"

"C" means "vertical" (ie, shows that the water electromagnetic valve inlet and outlet of the relative Angle is vertical, the water in and out of the gate of the electromagnetic valve of only two kinds of relative Angle, which is vertical, parallel, vertical in C letters, parallel in P letters, such as "C" D F - 270 - b with parallel F "P" D - 90 a).

5. The letter "F"

"F" stands for "valve", and all water inlet solenoid valves are named after F;